Balmar SG200, a good battery monitor gets better

Balmar’s Chris Witzgall stands with the SG-200 display at IBEX

I recently judged the Innovation Awards at the International Boat Builders’ Exposition (IBEX) and we selected the new Balmar SG200 battery monitor as the winner of the Electrical Products category.  The SG200 combines the goodness of the highly regarded original Smartgauge with a shunt to deliver a more complete picture of what your batteries are doing.

The first generation Smartgauge differed from almost every other battery monitor on the market by measuring a battery bank’s State of Charge (SoC) using just two voltage wires.  This meant that while the Smartgauge could tell you how charged your batteries were — somehow with more accuracy than more complex current counters according to power expert Rod Collins — it couldn’t tell you how much power was being used or replaced in real-time.  This lack of insight into consumption and charging was a significant limiting factor to many users.  Coupled with a very simple numeric-only display and the lack of support for lithium battery chemistries, there was definitely room for an update.

Enter the SG200.  Balmar has streamlined the user interface to a 2-inch, sunlight-readable color display.  It links to a sensor module named the SmartShunt via a 4-pin network connection called SmartLink. Since SmartLink allows the connection of 32 devices, you can monitor a large number of battery banks with displays located throughout the boat.  Each SmartShunt can also monitor voltage for two auxiliary batteries, like engine start or similar non-deep-cycle applications.

With the SG200, Balmar has begun measuring your battery bank’s State of Health (SoH), which is delivered as a percentage representing the battery bank’s current capacity versus design capacity.  The SG200 also reports on current consumption and total time remaining for the battery bank.  A mix of what Balmar calls active impedance compensation and shunt-based monitoring is used to deliver this level of insight.

Balmar says the SG200 can accurately measure State of Charge and State of Health for all major battery types including Lead Acid, AGM, Carbon Foam, TPPL and LiFePO4.  According to Chris Witzgall, the product manager for the SG200, it takes about three charge cycles for the SG200 to fully learn your battery bank’s characteristics and be able to accurately report on its status.  Unlike the original Smartgauge, the SG200 purportedly doesn’t lose accuracy while charging, and over time the system will get more accurate withut requiring calibration like typical coulomb counting shunt-based monitors.

Balmar’s planned options for the SG200 system include a Bluetooth gateway that will support a mobile app and a NMEA-2000 gateway that will make battery status and other metrics available on connected N2K instruments and MFDs. The basic SG200 gauge and shunt kit sells for $239 with limited availability until January, and the gateway prices aren’t yet known. Balmar has put up a good SG200 video here.

I’m hoping to install a SG200 on Have Another Day soon and look forward to reporting on the monitor’s ability to deliver on all the promise it shows.

Ben Stein

Ben Stein

Publisher of, passionate marine electronics enthusiast, 100-ton USCG master.

137 Responses

  1. Ben Ellison Ben Ellison says:

    Balmar’s new Smartguage looks really good to me. For one thing, a battery bank’s State of Health is quite important because you can not have accurate State of Charge if the bank no longer has the capacity it was meant to.

    Also, I’m happy to report that the SG200 is doing well so far in lab testing by Rod Collins: “It is pretty cool and so far on LiFePO4 the thing is posting within 1% on both SOH and SOC. That to me is quite amazing. One will be going on my own boat as soon as I can get a production model as Ah counters just don’t cut it.”

    Support Rod’s work here:

  2. Ben Ellison Ben Ellison says:

    According to Balmar’s Facebook page, the SG200 is “currently under a limited release…with full production launching January 1st” and those units are only available at PKYS:

  3. Lauren says:

    I would be curious to see how this works for people who run 100% renewable as for the charging. We lived on the hook for several years with both LiFePO4 batteries and a large solar array. the variable charging nature of solar and wind really seemed to confuse algorithms used. We cruised a few years ago, so had a link 20 and a BMV602, and after months of tweaking, found the victron to be slightly closer to the truth, but there were times where both got confused and reported wrong, but different situations confused them differently so having a second opinion was nice! Luckily we we had way more solar than we needed to keep charge and I understood what was going on, but I am curious if Balmar’s secret sauce actually works better in this scenario.

    • Ben Ellison Ben Ellison says:

      Well, the original Smartgauge definitely has an unusual way of tracking SoC — apparently termed “active impedance compensation” (I learned while editing this entry) — and according to Rod Collins there’s just no way that current counting alone can maintain accurate SoC over time.

      In my experience the 1st gen Smartgauge can get slightly confused when solar gain is high, but once the sun is down it’s much more accurate than my boat’s BMV (though it has umpteen adjustments I may have wrong ;-). Hopefully, the SG200 has it all completely right.

  4. Richard Cassano says:

    So, how do you program 32 devices? Is this done with push button codes? The Smartguage buttons are a nightmare to work with – some button presses work and sometimes not. I’ll wait for Rods report before I upgrade. Right now I’m happy to at least see the voltage on my house bank and starter battery.

    • Ben Stein Ben Stein says:


      Although the system has capacity for 32 devices, it’s hard for me to see a scenario where you’d be programming more than a small handful of SmartShunts. The new display has a single button and during my brief time at the booth using a demo unit I didn’t find any difficulty in getting it to respond to button pushes. Balmar uses a combination of short taps to change settings and long presses to confirm. It worked fine but is obviously quite limited in what settings can be changed this way. I’m guessing the mobile app will probably allow greater customization like naming of banks and the like.

      • Richard Cassano says:

        Great, that’s what I was hoping for, an App that allows programming rather than button pushes. I’ll never be programming 32 devices but for those with complex systems a programmable App would be welcome. Button pushing seems so primitive.

      • Ben Ellison Ben Ellison says:

        Actually, Balmar’s video briefly shows an SG200 app screen where you can custom name the shunts, the gauges, and the gateways. The narration also mentions that you can put shunts on loads like thrusters or refrigeration, so I think it’s possible to get that little display to show some sophisticated information in plain English. Check 2:44 here:

  5. Tim Leighton says:

    I’m encouraged that Balmar has joined the newer “family” of smarter shunt-based battery monitors. While I was happy with my SmartGage on our old sailboat I always wished it provided more information. Last spring the LINK system on our new-to-us Krogen 48 trawler died and I opted for the Victron 702 monitor which was very easy to install and has worked extremely well for us. I wonder what the differences are between those two systems.

    • Ben Stein Ben Stein says:


      The biggest difference is that the Victron system is strictly coulomb counting. As a result it’s prone to drifting out of accuracy and doesn’t have any idea what age has done to the capacity of the battery bank it’s monitoring. If you told it you have a 1,000ah bank but age has reduced your capacity to 800ah it’s still assuming you have 1,000ah available.

  6. Leslie Troyer says:

    I ordered one in Annapolis – hope they make the Bluetooth API available. It would be nice to track this with Signalk. They said it will be delivered end of this month.

  7. Grant says:

    “…and a NMEA-2000 gateway that will make battery status and other metrics available on connected N2K instruments and MFDs.”
    That’s maybe the best news of all – right now, trying to monitor multiple battery bank voltages using NMEA2000 requires buying a separate NMEA2000 voltage monitor for each bank. The only product I know of that does that is Maretron’s DCM100 at $495 MSRP – plus an additional Maretron device to program them (USB100, etc.)
    For a twin-engine boat with genset, its not uncommon to have 4 battery banks – so that’s over $2,000 just to read battery voltage on a NMEA 2000 display! I’m glad somebody finally addressed this, to say nothing of the other capabilities of the SG200. Looking forward to seeing it soon!

  8. Rick R says:

    Can this be used to trigger an Automatic Generator Start at say 50% SOC, and is there an audible alarm to draw attention to a fault or alert? I didn’t see either in the owners manual.

    Balmar needs to hurry up and include bluetooth with every unit, since Victron 702 has had this feature for several years. Hopefully the SG 200 prompts Victron to add a battery State of Health feature.

    • Ben Stein Ben Stein says:

      Looking through the specs and wiring diagrams I don’t see a relay output of any sort. That would be one way to enable generator starting at a given SOC. Without that, I think the most likely way to achieve this would be with NMEA-2000 output and then use a device that monitors the PGN for SOC and takes action when it crosses a threshold. Not a simple solution.

      Right now it seems like Balmar is on the same path as Victron was with the 702, Bluetooth being an add-on option (on the BMV-702 it connects to the VE.NET port) but the BMV-712 now has it built in.

  9. Anonymous says:

    Whats the relationship to Merlin Equipment, who made the original smartgauge, as Balmar were just rebranding it for the US market.

    I’m in the UK, will I be able to get it from Merlin, or are they not involved in the SG200?

    • Ben Stein Ben Stein says:

      My understanding is that Balmar has engineered the SG-200 themselves and I don’t believe Merlin was involved. I haven’t heard anything about any agreements with Merlin for them to sell it in the UK but I’ll reach out and ask.

  10. Saffy The Pook says:

    I sure hope that every configuration setting can be made without the need for the app & bluetooth module. I have no need or desire for the bluetooth module otherwise and having to pay extra just to set the thing up is a deal breaker for me.

  11. Hi all, I’m the funny looking guy at the top of the post. I figured I would attempt to answer a few of the questions here. While there are some similarities at how the original SmartGauge calculates SoC compared to the SG200, there are some big differences. Note we are not calling this SmartGauge 2, or something like that.

    Active Impedance Compensation is not something the SmartGauge does, only the SG200. It should have no issues with Solar and lower amperage charging sources. Although we may find a use for it in the future, Peukert is not used to calculate SoC. This is important because it is actually kinda hard to get this number right, and it is actually not constant, but varies as batteries age, and as even as they charge and discharge. We are currently only using it for Time Remaining.

    A N2k and or Canbus connectivity is something we anticipate adding in the future. Although there is a State of Health PGN, the only place I think it is view-able is on a Maretron display.

    Additional shunts are viable to use to monitor any load or charging source, but when it comes to SoH on a battery or bank, we need to see a cycling, both charge and discharge over time, to make that calculation. This is why we are not recommending a Separate SmartShunt for starter batteries.


    Programming the devices is pretty darn simple. Just select a chemistry, and then the design capacity of the battery or bank. That is it. Additionally, you can define alerts for the difference SmartShunts. There is currently no audio buzzer or sound alert, only on screen. We have some ideas about a I/O or relay module, this could be incorporated in that.

  12. Grant Jenkins says:

    Chris, thanks for the clarifications. Really hoping you can program it to output at least a basic PGN (127506 or 508) containing even just DC Volts for display on other NMEA2000 displays. Look forward to seeing the product at the Seattle show perhaps in January?

  13. Ted Arisaka says:

    I hope the BT connected app technology can be leveraged to program a future version of you MC614 external regulator. I stole Rod Collins idea of programming it off the boat, but I still need the instruction manual in front of me and that darn screwdriver with the magnetic tip 🙂

  14. Ian Kelly says:

    Hmm – seems like a move in the right direction
    is it know if this device will talk with the original smart bank ? ( the brother to the smart guage?)
    major pity if this didn’t have this funcionality

  15. Leslie Troyer says:

    Got the display installed today an the cable run to the battery compartment. Next is shunt install and testing.

  16. Saffy The Pook says:

    Any idea what the shunt resistance is? I have an existing 50mV/500A shunt for my inverter/charger and would have to either put it in series with the Smart Shunt (which I don’t want to do) or just use the SS in place of my current shunt and have it do double duty by putting the charger’s sense wires across the Smart Shunt but I could only do that if it matches the specs of the current one.

    • Ben Stein Ben Stein says:

      Saffy, I’ve reached out to Balmar to see if they can provide that information. I’ll let you know if i hear back or Chris might chime in directly here.

    • Saffy,

      While our shunt is compatible from a resistance standpoint, this is not something we have tested for and it very well could really mess things up with some of our internal calculations done in the SmartShunt. We are measuring a very tiny voltage at a high degree of accuracy, anything that throws that would be very detrimental to the SG200 operation. Much more so than a traditional coloumb counting shunt.

      Having said that, there is no issue with putting the SmartShunt in series with another shunt.While i may not be the most elegant solution, we have done this with no inpact to the SG200 performance.

      • Saffy The Pook says:

        Thanks, Chris. Series is an option if there’s no alternative.

      • Jorgen says:

        I also look forward to replacing the smarthauge (and perhaps even Maratron ) with this new devise.
        But why is it that this new design does not use coils (such as Maretron) to measure current so that the user do not have to cut the conducting cable?

        • Ben Stein Ben Stein says:

          Perhaps Chris will chime in on this but I believe (at least part of) the reason is that in order to measure resistance as the SG-200 does they need hard connections to the battery and not just the flow of current as a typical CT does.

      • Phil Mummah says:

        Does this mean the Balmar SG200 has a 500 amp, 50 mv shunt? Thank you.

  17. Saffy The Pook says:

    Thanks, Ben.

  18. Peter Jung says:

    My house battery bank (2, 8D AGMs) is now two years old, and has undergone significant charge/discharge cycles in those two years. Short of doing a 20-hour rate discharge test on my existing battery bank to establish the current SOH of my bank, how will it determine SOH of an “experienced” battery bank such as mine?

    • Ben Stein Ben Stein says:

      According to Balmar that’s the magic of the SG-200. Their algorithms will know what the characteristics of an aged battery look like and evaluate your battery based on those characteristics to determine its actual capacity. I haven’t had the chance to evaluate that on my boat yet but expect to do so in the next month or so. I also have an experienced bank made up of 8 FLA GC2 batteries.

    • Pete and All,
      Pete sent in a request for this information to our support email so I responded to him there. I am posting it here, since he asked here too:


      I received your request for more information about how the SG200 works, specifically when connected to aged batteries. Over several charge/discharge cycles, the Monitor will establish the SoH of the battery or bank. The number of cycles is not set in stone, but typically is from 2-6 cycles. Note that the accuracy of this is will be skewed if the battery does not receive at least one full charge, all the way to the top. For instance, it it calculated that your SoH is 92%, but the charging was stopped when 2% of the usable capacity was not “Charged’ then the SoH will be off by that 2%.

      Based on some continuing testing we are doing, we may be able to document a procedure to shorten the time needed to get a good SoH figure.


  19. Anonymous says:

    Hi Ben,

    Well, huh. I’m hopeful Balmar will provide some amplifying details of how their algorithm “queries” the battery bank to determine SOH. I’ve asked them, no answer to date. As I expect the algorithms and hardware are intensely proprietary, I’m not hopeful for much of an answer. Perhaps Rod Collins will weigh in here, or on his web site.

    If Balmar’s assertion proves to be correct and accurate, seems like a further variant of the SG200 would obviate 99% of the SOH “battery testers” currently in use today by battery retailers, auto repair shops, Harbor Freight, NAPA, and a myriad of others. The vast majority of which, IMHO, seem simply worthless.

    The SG200 seems REALLY promising, and I’m tempted to acquire one ASAP. Kudos to Balmar! And thanks to you for the heads up on this instrument.



  20. Ben Ellison Ben Ellison says:

    Happy to report that I encountered two more battery monitors claiming to deduce battery State of Health at METS. One is a Scheiber Intelligent Battery Monitor kit now being sold in the U.S. by MarineBeam, who also explain it well:

    The other is not yet described online but Sentinel Marine Solutions has new IBS (Intelligent Battery Sensor) that can output results over NMEA 2000 as well as off boat:

    • Hi Ben,
      The Sentinel Marine unit seems to be simply a voltage sensor – it would let you know if you are low/high (along with lots of other things – it seems to be primarily a security device). The Scheiber unit looks more interesting, but appears to be limited to post-type batteries, as mounting their sensor on a tab-type battery like my Lifeline 8Ds wouldn’t work without significant kludgery 🙁 .

      It strikes me that many of the folks looking at these units probably already have one or more shunts installed for an existing amp-counter device — it would be nice if these things could be configured to use these existing shunts, making installation much simpler!

      • We actually had an early prototype that mounted directly onto a battery stud (Not post). We moved away from that, mostly because it made the battery installation taller, and from my experience that was something that would limit installation in many circumstances. We also made the choice not to use an already available automotive sensor for performance (max Amp draw etc).

        If we were just measuring current flow, then using existing shunts would have been an option. However we are also making other measurements including impedance, and we require a factory calibrated package for our performance targets.

        • Hi Chris.
          I do understand regarding a standardized connection.
          Two questions: first, are the terminals on the SmartShunt 3/8″? Second, your diagram seems to show that the start/aux battery negatives run through the shunt – wouldn’t the starting (or running, like for a thruster) current and charging current to the start/aux batteries confuse the readout of other currents in the system?

          • Leslie Troyer says:

            The shunt in the SG200 is what Balmar calls a smart shunt. It does contain a normal shunt, but also contains a microprocessor that does all the math and necessary calculations for monitoring the battery. The microprocessor must have two “spare” analogue to digital converters.
            The unit uses thes to measure the voltage of the other batterie sets. Electrically they are isolated from the actual shunt proper.

          • Hi Leslie,
            That’s what I would have thought, but if you look at the diagram above (it’s also on BalMar’s website) you will see that they have wired the start/aux battery negatives through the shunt as well. Perhaps this is a drafting error, but it could be significant.

          • On a standard installation utilizing the auxiliary leads, we assume that there is a common ground. If not, then additional leads will need to be installed from the aux battery back to the SmartShunt. If you read the note, it states “Negative leads on Aux. Batteries are Only Needed on Isolated Ground Systems”.
            This won’t be the case on most installations, It will work fine just running one of the orange aux leads to the positive side of the aux battery. Don’t forget to install a fuse there, sized for the wire run (there is no appreciable current flowing.)

            An additional note about fuses. Some may wonder why we include a 10a fuse for the shunt/system power, when it draws much less power. The fuse is sized for the wire properly, and we have found that there is a decent different between the resistance of a 1a fuse and a 10a fuse, so the voltage readings are a bit more accurate.

  21. Ian Kelly says:

    Hey Anonymous Pete – its probably not BALMARS IP – they have been using the smart gauge monitor from the UK for years see – – my guess is that this bit of magic actually belongs to Merlin. again a guess they will be manufacturing under license condition.

    • Ian,

      The SG200 was 100% developed and is 100% owned by Balmar LLC. Balmar is the sole owner of the IP behind the product. Merlin was not and is not involved with the product at all.

  22. Jonathan Woytek says:

    Someone had previously asked about differences between the SG200 and the Victron BMV 700 series devices. In addition to the important tech differences, it is interesting to note that the BMV712 specs quote a 1mA draw, and the SG200 specs quote a 10mA draw in sleep mode (both at 12V).

    I’m currently evaluating battery monitors for a new-to-me sailboat. The existing DC system is pretty simple with an older shunt-based energy monitor installed. Im going to be adding some new loads with nav electronics, and have an eye to install some solar charging in the future. I want to have a good handle on the existing battery bank first, though. Thanks for bringing the SG200 into my evaluation process!

    • Johnathan,

      There are some savings in power we can implement, it is on our future development list. While I am not sure we will ever get down to 1ma, it should be a good percentage savings. Our processor is much more capable (needed for our performance criteria), but that comes at a cost.

      • Jonathan Woytek says:

        Thanks for the reply, Chris! That’s great to hear that there could be some future savings there, too. Certainly, 10mA is not a deal-breaking number. It represents only about 240mA per day, or about 7A over the course of a month. In my use case, since I live in an area that freezes over the winter, the boat will be on the hard out of season, and I’ll be depending on doing some solar-based battery maintenance while out of the water.

        Does the unit have an automatic low-voltage shutdown to avoid killing a battery in the event of loss of long-term loss of charging current?

  23. PaulGel says:

    Now if Balmar would do a remote monitor for their regulators rather than a red light on the dash panel then I would sign up. I hate sitting in the engine room waiting for all three of them to cycle through their processes.

    How about it Balmar? Maybe even Bluetooth.

  24. Leslie Troyer says:

    Early adopters of the SG200 will get them free later this month. In order to hit the fall shows they shipped not knowing if the firmware was 100%. The only way to update the firmware is via Bluetooth.

  25. Tony van Wouw says:

    Not really ready for prime time yet, disappointed with the performance.
    I installed mine about a month ago and found that the state of health reading is unstable. I know from doing a 20 hr discharge test that the battery capacity is about 70AH. Although the meter does sometimes show SOH at 68% it also flips back to 100% for no apparent reason. This affects the SOC reading which is then wildly inaccurate.
    I have spoken to Chris and emailed my findings to him… I feel like an accidental product beta tester. The only solution that I see is a new firmware upgrade which is not feasible until they get the Bluetooth bugs figured out.
    Don’t really want or need the Bluetooth interface I just want it to work reliably. What I have now is a very expensive voltmeter/ammeter
    My installation is really simple… a single 100AH gel cell and a mastervolt 50A smart charger.

  26. The SG200 was over three years in the making, involving over 2500 hours of battery testing in our lab. It also included a group of external testers, with many different battery types and installations. Despite all this testing, we knew there might be conditions or situations that we and our testers did not encounter.

    We are aware of the issue with the State of Health mentioned. Essentially, the SG200 has calculated an SoH that is a “Correct Value” however, in certain circumstances the control software replaces the “Correct Value” with a 100% value. We can address this in a firmware update.

    Currently our development team is devoting all their time to getting the Bluetooth Gateway and associated App ready for the marketplace. We need this functionality in place before any other issues can be addressed, as downloads from the Gateway App are THE method for updating the software and fixing any bugs.

  27. Anonymous says:

    Is there a way to update the software without the bluetooth accessory? I shouldn’t have to pay extra for the ability to install updates to correct product deficiencies.

  28. Paul L. Bellefontaine says:

    Is a 500 amp shunt an adequate size for a vessel that has it’s bow and stern thrusters and starting motor feeding through the one negative line to it? I have a Mainship 400 with sidepower thrusters and am installing a Xantrax LInk Pro. The shunt looks to be pretty lightly built relative to the massive battery cables.

  29. Paul,

    I cannot say about the Xantrex shunt, but the Balmar SmartAhunt can handle 350a continuously, and 600a for 10 minutes. I don’t think any recreational thruster could draw that much for 10 minutes, it would overheat and shut down way before then.

    • I am in the process of building out a whole new DC battery system and monitoring, and was seriously considering the SG200 but for this limitation. 350A continuous is pretty low compared to every other shunt I have come across, which usually top out at 500A minimum.

      Considering that an average 3000W inverter from the likes of Magnum, Victron, and MasterVolt require a 350-400A fuse alone, this seems like a really big issue, requiring two SG200 shunts, bus bars, and a lot more wiring and potential failure points.

      I know a lot of the brains are in the shunt, but it would have been nice for it to be the same size amperage wise as all of the rest of them out there. Surprising, since power systems and batteries continue to get smaller and more intense….

      • Ben Stein Ben Stein says:


        I’m not sure the ratings of the Balmar shunt will provide any trouble, even in the case of a 3000w inverter running at pretty high loads. I’ve never seen house bank loads sit even at 300a for any sustained period of time. Certainly an occasional microwave or coffee maker load for relatively short periods of time will push into that range as will thrusters, but not for 10 minutes even at 300a let alone the 600a Balmar says is safe for up to 10 minutes. I will say, I think Balmar’s way of rating the shunt makes the comparison difficult but, I think the implication of it being safe for 10 minutes at 600a implies it can also measure 600a loads, which might make it more like a 600a /50mv shunt. I’ve not seen ratings on other shunts given in sustained and peak currents.


        • Thanks Ben. The reality of our rating was that we could not hold 600a for longer than 10 minutes in the lab, so we stuck with that rating. Our criteria is the internal temperature of critical components in the Smartshunt, and they were still at safe levels in that 10 minute period.

          It may also be interesting to note that many manufacturers use complete shunt assemblies made overseas, that are rated by the supplier. We assemble ours in our plant located in Huntsville, AL.

          We also hope to have a provision for ganging up shunts in parallel to increase the ratings to 700a/1200a respectively, in software. This would require the use of the BT gateway, coming soon.

          You spot on about the inverter loads, though. Most 3000w inverters will self throttle back on the available current way before the 10 minute mark. I have a Victron 24v inverter (Great unit) on my boat, and there is no way it will hold 3000w for long periods. The heat will limit it. We also have the 12v version in the lab, and perhaps we will test this in the future.

        • I think 600A is fine for short time periods, but I am still going to have issues with the 350A number. I have 2x 200A alternators plus a 120A charger that can be running simultaneously while underway which would give me 520A. The alternators won’t be running flat out all the time, but even if they are running at 150A each, that is 420A total. Remove the charger, and I’m at 300A, but that doesn’t count solar, which is being installed later this year, and any other charge sources. My house loads are not terribly high, but that has to be factored in as well. Any of those scenarios have me over their 350A number.

          Since it is a LiFePO4 bank I’m charging, I will be charging for less time than a traditional bank, so there is that, but it still will be more than 10 minutes. And I am curious how useful an SG200 would be with LiFePO4 anyhow…

          I have seen a Victron 3000W inverter on my previous boat get right up to 300 amps regularly when using an espresso maker + other normal outlets and devices. If we take that, which usually lasts a few minutes, plus a moderate house load, you could easily be over 350A for longer than 10 minutes.

          Regardless, I never like designing anything where I am regularly exceeding a limit in the case where something could fail / catch fire. I have also never seen any other shunt list a sustained current vs. max and have seen Victron and Magnum 500A/50mV shunts run at 400+ amps continuously without any issues.

          • Steve,

            I assume it is a reasonably large LiFepo4 bank? With those charging sources, I would wait until we have the 2-shunt parallel scheme up and running. At those amperages, getting 100% crimps on cables etc become very important. Have you considered changing to a 24v system?

          • Hi Chris,
            For some reason I can’t reply to your comment, so I’m replying to mine…

            I will definitely look for the 2-shunt solution in the future.

            I did consider switching to 24V but as the boat has so many things already at 12V, and using DC-DC converters would have required quite a bit more complexity, I stayed with 12V. There are definite advantages in terms of cable sizes, amperages, and the like, but it just didn’t work out in this particular install.

          • Grant Jenkins says:

            Steve, I’m curious how you plan to combine all your charging capacity into a single bank – I suppose you could use a Balmar Centerfielder and appropriate Balmar regulators to combine the outputs from your alternators, but how are you adding the battery chargers output into the mix? And would you really be running your genset while underway, just to run the battery charger? I’m not sure that just adding the sum of your various charging sources outputs’ is realistic in considering the potential loads the shunt might see…

          • Hi Grant,
            I am using a regulator system from another vendor which I will be writing about soon. It is similar to the Balmar MC-614 + Centerfielder approach but uses a few more pieces of data when charging, and in testing has shown to be very effective with two engines + two alternators. Those alternators are both directly connected to the house bank, not to the start bank and then ACRs, etc.

            I expect that setup to pump out about 300 amps continuously while underway, but of course I am going to wait to 100% confirm that until I have some time on the water with that solution.

            I do routinely run my generator while underway for a few reasons. First, my watermaker requires it to be on to make water, and on longer trips, I do that every day for a couple of hours. Second, my water heater only heats off of shore or generator, so usually in the morning we run it for an hour for showers and dishes. On top of that, we run it whenever I am using the windlass for anchoring to ensure that battery bank is topped up as the windlass eats quite a bit.

            So, if we’re running the generator at any of those points while we’re also motoring, I would definitely have 420 amps of inbound battery charge easily (300 from alternators, 120 from Victron). I could configure the Victron to not charge while the engines are charging, but why? If the generator is already on, I should be loading it as much as possible to get the best use out of the fuel being burned, and charge the batteries a bit faster.

            There are two other DC to DC chargers that use the house bank as their source, and charge the generator and start battery banks. I chose this configuration over having other AC chargers because it allows for simpler charging whether at the dock or underway, and ensures I can always start my engines and generator.

  30. Ben Ellison Ben Ellison says:

    Sounds like Rod Collins at Marine How To has tested all sorts of batteries with the SG200 and is happy with results:

  31. Grant Jenkins says:

    Thanks for your response – I’ll be interested to see your report on this other vendors hardware, which apparently allows simultaneous DC charging from 2 alternators, PLUS an additional AC powered battery charger (or inverter/charger). I have not seen this anywhere. More typically, I see folks connecting two internally-regulated alternators into a single house bank, blissfully unaware that they are NOT getting anything close to the combined alternators output that they think they are… As far as what I’ve seen to date, Balmar’s solution is the only one that actually addresses this configuration.
    As far as using the genset underway for charging – sure, if you’re running it anyhow for the watermaker, why not? I’m just not aware of how you manage that charging, combined with the alternators output (especially for newer technology banks like carbon foam or LiFePO4) to achieve the specific charge profile required.
    I’m also curious about your last statement, regarding DC-DC chargers from your house bank to the gen and start banks – if it’s all 12V, why not just use an ACR? Unless your DC-DC charger supports some kind of individualized, programmable charge profiles? Again, not something I’ve seen much about….

    • Grant,
      The other hardware is supposed to be able to handle dual alternators and use more information than a traditional system to allow for not only their charging, but other charge sources. Dual alternators with decent regulators will work mostly fine up until the last portion of charging in my experience. There are some situations where the regulators will also fight eachother, or one will work and the other won’t. This system solves that, so I will be very interested to see the overall performance.

      In terms of the charging profile, I’m supposed to be able to match the inverter charger profile with the regulator, but that is something I will be working on this next week. There may be some conflicts in this situation, and if that is the case, then I’ll wire a cutoff for when the regulators are running to make sure the inverter isn’t charging as well.

      The DC-DC chargers are a product I’ve used a number of times before from Sterling Power. They are going to consume 12v DC from the house bank, and output 12v DC for my start and generator banks. There will be two of these devices, and they have a full charge profiles so I can ensure that my nice AGM start batteries are being charged nicely. I’ve done the ACR thing before and you’re essentially at the mercy of whatever charge profile your house bank / other charge source is set to. I’ve used these in other situations where charging profiles are important, or where you are stepping down/up voltages, such as for a windlass bank.

  32. Jenkins Grant says:

    Steve, thanks for your response. Sounds like a very advanced system. I’ll look forward to hearing how the new hardware performs, when you’ve had a chance to use it.
    I like the idea of the Sterling chargers, if they allow individual output profiles – as you point out, that is the downfall of traditional ACR’s when combining batteries of different technologies. I’ll check them out. Thanks!

    • Hi Grant,
      I’ve been using this system now for about 5 months, and finished the write up at

      One of the key pieces of tech is the Wakespeed regulator which is able to coordinate the overall charging result via more than traditional regulators using a CAN bus connection between the two regulators plus using a shunt to see current in/out of the battery bank.

      • Grant says:

        Hi Steve, thanks for the heads up on your latest Seabits post – I got about 1/2 way through it before I had to leave for work.. I’m looking forward to digging into it in detail tomorrow.
        The Wakespeed product sounds awesome, not sure where you find this stuff!

  33. Jman says:

    Is there any guarantee that a particular brand of 12v lifepo4 drop in will work well? There are about a dozen brands outside of NA, if balmar didnt test them will they work? I ask as it looks like the sg200 has soh and soc accuracy issues with some 12v agms which are not true deep cycle.

  34. John says:

    On April 16 Chris Wetzgall of Balmar said “Currently our development team is devoting all their time to getting the Bluetooth Gateway and associated App ready for the marketplace. We need this functionality in place before any other issues can be addressed, as downloads from the Gateway App are THE method for updating the software and fixing any bugs.”

    Yet, we have no BT module yet, and therefore no bug fixes for units in the field. Another sailing season on the East Coast has come, and almost gone, without an update.

    Or perhaps there is an update I’m not aware of?

  35. Leslie Troyer says:

    I’m surprised by the lack of communication from Balmar. They know who purchased with promise of the gateway so they can contact us. Communication seems to be Internet forums or here from people who called to inquire on status. This is an example of very poor customer service.

    If you want another I inquired about a serpentine belt kit for my 83 C36 with a M25 engine. It is marketed specifically for the M25. The response after providing pictures of my crank pulley was “we don’t make one for that year of M25” – I know for a fact that the same pulley was use until 1987 – more than 80% the life of the M25 but no mention of this on their product page or what you need to look for before ordering.

    Really poor customer Orientation.

    • John says:

      Watch your step, Les! I was banned from sailboatowners today, apparently for expressing my opinion on Balmar too strongly. Or maybe RC took offense. We’ll see.

      • Ben Stein Ben Stein says:

        We aren’t much into banning here. Keep it civil and avoid name calling and all will be well. I haven’t seen anything problematic so far.

        • John says:

          Thank you, Ben. Just to be clear, I wasn’t warning Les about a ban on this site. I appreciate your open discussion policy.

      • Saffy The Pook says:

        Seriously? I buy a fair amount of stuff from sailboatowners but if this is their response to a civil but critical commont, I’ll have to reconsider. Likewise for RC, who seems to have stepped beyond the role of Balmar beta tester to Balmar apologist. RC’s biggest asset, whether he realizes it or not, is his impartiality and not just his technical information. If he loses his impartiality, the technical information loses credibility.

  36. All,

    I am away for the office for the week, but I wanted to address the delays in the BT gateway. Due to a variety of issues, the development has taken way longer than we initially planned for. Rest assured we have been working on it diligently. We are now in beta testing, and crossing fingers it will be released sooner than later. I don’t want to insult anyone with a date, but it should be well before anyone points back to this email and says “Chris said….” To Leslie, I know you and I were in communications some months ago, my apologies for not giving you an update.

    • John says:

      Thanks for the update, Chris, especially since you are on vacation. A regular email blast to registered users costs nothing and would go a long way in customer care.

      I confess I find it remarkable that you could work on something so simple for so long. Is this really just a BT dongle development, or is something more going on?

  37. Jag says:

    Any news on the BT gateway ?

  38. Leslie Troyer says:

    I should be getting mine very soon. They mailed it friday.

  39. Tony van Wouw says:

    SG200 battery monitor…. an update

    I bought the SG200 because of its ability to constantly (and without user intervention) monitor battery capacity and state of health (SOH). With the Bluetooth gateway release and delivery (finally), I figured that the past problems were behind us. Spoiler alert – it is considerably better than before but still a product that is maturing.

    Note: Some of the comments apply only to LiFePO4 chemistry used on my boat.

    1. Looking at the app on the smartphone, I noticed that the internal math for time remaining calculation simply didn’t make sense at some discharge rates. Chris acknowledges that there is a bug in the time remaining calculation which has been recognized and will be fixed in the next software release. One example was that with a 3A discharge I only had five hours remaining – yet at 9A discharge rate I had 8 hours remaining. Using the formula capacity remaining in AH = discharge rate X time remaining, the former indicated that I had 15AH capacity available – yet under the same SOC the latter indicated that I had 72AH left. The latter case was realistic based on the bench testing of the battery.

    2. Software updating is an opaque process. There is no instruction manual for the app nor does the web-site reveal the current software revisions or how new software may be obtained. As before, this is acknowledged and is being worked on. For now the latest software is V2.58 for the shunt and V2.57 for the display. Chris indicated that a new release will be delivered soon that addresses many of the issues described in this note.

    3. Default Max charge voltage in settings for LiFePO4 is wrong – should be set to at least 13.7V not the 13.2V that is presented by default.

    4. The App does not show the “+” sign after SOC to indicate that full charge termination has been reached. – Chris replied that this feature will be added in an upcoming release…. It is important to note that for the SG200 to do its magic, charge termination must be achieved. Refer to page 21 of the manual (Rev C version) for further information.
    5. There is no security to gain access to the gateway – while this is not a safety issue it will be for the new BT regulators. Chris noted that they are actively working on this.

    6. The SOH reading remains suspect (more wrong math?). See notes below. This is likely due to the original testing for LiFePO4 chemistry – likely done on larger prismatic cell packs. According to Chris, Balmar is continuously testing to see if any improvements can be made, and if different profiles are needed for different battery/size combinations to improve accuracy and to strengthen the product performance.

    7. The factory reset appears to not really be a clean start. After discussing this with Chris, I was informed that it keeps the chemistry already selected, changes the capacity to 100ah, and resets all other data. However, the SOH number that initially comes up after several discharge cycles remains the same regardless of the battery capacity selected. Before the latest software and gateway was installed, it was always 92% (occasionally flipping to 100%), after the upgrade with the gateway it stubbornly remains at 89% SOH – regardless of the battery capacity setting. I am conducting a series of discharge tests to determine if this is actually the case – the battery capacity has been set to 75AH and currently I am on my third discharge/charge cycle.

    8. The “Aux voltage 1” always reads about 0.15 to 0.2V low. I am apparently the first to report this – not a big deal but if this is software adjustable it should be looked into for later releases.

    9. At one point, “Aux voltage 2″ triggered a low voltage alarm. To remove the history of the alarm requires a reset. The unused wire is now connected to ground. Chris is aware of this based on feedback from others and the issue is resolved in the next release.
    10. The app title is ”BANK-02”. Why 2? Not an issue but I only have one battery. This is addressed in the next release and apparently users will be able to rename some of the devices to suit.
    11. The SOC counts down under load to give the users a sense of power remaining. Based on our discussion I understand that when the gauge reads 0% the battery is actually still at 20%. This is only for LiFePO4 chemistry. For FLA I believe that the 0% number is about 50% remaining capacity. Having a published figure on the website or in the manual for all of the chemistry choices would allow users to decide how far beyond this they can safely go. Chris indicated that they will be allowing the user to change the “Time remaining to “X%” value in a forthcoming app release.

    So ….. improvements are on the way …

    Some background:

    About a month ago, I finally received the BT dongle for the SG200 and I was able start the device battery learning again, using the “latest” software which, as of this date is V2.58 for the shunt and V2.57 for the display. The upgrade started well but after the SmartShunt update appeared to be finished the system became unresponsive (shunt not recognized in the network) and required a power down reset (battery disconnected for 10 seconds). There were no real instructions or manual, but based on my experience you have to be patient and respond to the prompts that may appear on the colour display.

    My installation is quite simple and consists of a single 100AH LiFePO4 drop in battery ( this battery is a re-purposed unit from several samples proposed for a telecom client) with a simple BMS that does passive top balancing and uses low side N-channel MOSFETS for protection from over/under voltage conditions. The internal construction is 4S/5P and uses 20AH pouch cells (model # AMP20M1HD-A). The charger is a CC/CV 50 capable power supply set for 13.85 volts; it is disconnected by means of a voltage sensing relay when the battery is at or above 13.8 volts. The boat has a 10hp outboard with a 6A alternator which is voltage limited to 14V using a high voltage disconnect relay. The outboard is only running for short periods of time and always when there are other loads present – these loads range from 2-8A while underway.

    Regarding the battery bench testing, this was done starting at 13.8V which is assumed to be >98% SOC. A constant power discharge rate of nominally 8.5A to 12.0V (under load using an inverter and resistive 115V load) gave an average of 102AH capacity. After resting the battery for an hour, the open circuit voltage came back up to 12.4V which according to most published literature is about 10% SOC.

    The SG200 was installed in March of 2019. After several discharge/recharge cycles, the SOH reading reported 92%. Not the same as my bench tests but reasonably close. This reading never changed regardless of what battery capacity I entered and what value I set for max charge voltage. Item 7 above describes the symptoms. I never really gained any confidence that the SOH reading was accurate so I only relied on the SOC to gauge battery capacity.

    With the installation of the gateway in early October, the issue of SOH being “sticky” (despite factory re-set and selection of battery capacity other than what is actually fitted) remains albeit now a different (89%) value. As noted in item 7 above, I am conducting additional tests to verify this observation.

    I am a PE specializing in telecommunications – I’m used to dealing with “bleeding edge” microwave radio and related equipment. The kind of magic that the SG200 tries to perform is not simple and the stumbles with the gateway development attest to that. Solving the unforeseen problems and field feed-back are essential to getting it right. So far, I can say that Chris and Balmar have been very responsive to feedback and I look forward to on-going improvement in the performance of the SG200.

  40. To add to the above, I also recently received the blue tooth gateway and the updated display, which I had difficulty connecting to my android based app. The following steps resolved my difficulties.
    1. The location services must be enabled on the phone App, or it will not connect, giving a vague error of no gateway on network.
    2. When I connected the gateway to the left port of the display and the shunt to the right port when facing forward, it did not connect. Switching the ports around caused it to connect.

    I was on the phone with tech support throughout this process and the above symptoms were news to them. Hope this helps the group.

  41. John says:

    Tony, thanks for the excellent report. Here’s my take: you are happy to be a member of a development team, working on a product that is not only not quite complete, but has evidence of blowing very rudimentary feature implementations. As for the stumbles in the BT gateway development attesting to the “not simple” nature of this development, I must disagree; putting BT on just about anything these days is common and quite simple.

    I might be interested in this if it was “done” – features working properly, reliable, robust, not finicky. Certainly not in this stat.

  42. All,

    We have released a new app that is now available on both the Google Play store and the Apple store.

    If after installing, please upgrade the BT Gateway first. Depending on your phone and OS version, you may have issues connecting or performing upgrades to the Color Display or SmartShunt, due to persistent Bluetooth Cache. If you have issues, the cache can usually be cleared by turning off bluetooth, waiting 10 seconds, and then turning it back on. If that does not work, just restart your device (Phone or tablet.)

    Finally, in some circumstances you many not see all of the your devices listed after upgrading. If so, simply pull power (Fuse) from the system and then reinstall.

    Here are the basic release notes for the update:

    New Features:
    1. Ability to rename devices, visible on both the App and the Color DIsplay.
    2. When multiple devices of the same type are on the network, and they have different names, they can now be updated in turn while remaining in-place on the SmartLink network.
    3. Improved display of the Firmware upgrade process using two progress bars.
    1. Preventing a situation where if the chemistry upgrade process were interrupted, device memory could become corrupted.
    2. Prevents false voltage faults when upgrading firmware with 24, 48v bank voltages.
    3. General network reliability and connectivity improvements
    4. Removed voltage faults on Auxiliary voltage leads.
    5. The app now prohibits device screen lock while an upgrade is in progress.

  43. I’m curious to hear more reports about the the SG200 with LiFePO4 banks.

    I’m about to replace my Mastervolt BattMon Lite with 500a shunt. I’ve found the coulomb counting to be way off mostly only the charging side. It wasn’t great with my FLA bank unless they reach 100% SOC regularly, but it’s worse with my LFP bank that is normally charged to 13.8 (sometimes 14.2v) then ‘floated’ at 13.2v

    I’d like to know how the SG200 handles that scenario.

    I’m also curious to know if it can run headless with just the bluetooth gateway. Even better is it’s possible to output data to signalk or NMEA2000

    Thirdly, there is absolutely no talk of relay control or external alarm. Can this output a current that could control a relay or alarm?

    And what of temperature monitoring? Surely that is important?

    I’ve been leaning towards the Victron BMV-712, but I’m not hearing great things about it paired with LFP banks, though with VE.Direct and Venus OS it can at least connect via NMEA2000.

  44. Mike,
    We have many users with the SG200 and LiFePo4 batteries, and many good reports of its performance. We also have encountered some issues, and have been actively addressing them. A new set of chemistries that apply what we have learned (Much through customer feedback) over the last year is being worked on right now, hopefully released soon.

    You can indeed run headless without a display. Of course the display is really nice, so We don’t have any relay control right now, but this may come in the future – you are not the first to ask. Battery temperature monitoring is not as important with the SG200 as other products due to the way we do things. If you had wind swings in the ambient battery box temps it could in theory induces a small amount of error, but we have not found that to be the case in practice.

    NMEA 2000 output is on the roadmap, but I cannot say when at this time.

    One of the the biggest issues with traditional coulomb counting devices you will find (VS the SG200) is dealing with synchronization errors, the result being that the SOC can drift out of accuracy over time.


  45. Jack says:

    I bought an SG200 in October 2019 and find the user interface to be pretty good, and the display is great. I like that it displays state of charge rather than amp-hours. Though I’m an electronics engineer, my crew is not and Ah was always confusing to them. But I upgraded the firmware in December and now the thing is a brick. It doesn’t go to the real-time display, and it reboots frequently. Tech support says there will be a fix “in a few weeks,” but in the meanwhile I’m left hanging. This is such an egregious failure my faith in the unit is gone.

    • John says:

      Thanks for the report. I wouldn’t consider this a product-ready device, certainly wouldn’t want to depend on it.

    • Ben Ellison Ben Ellison says:

      Hi Jack, a reader named Andrzej tried to reply to your comment with this:

      “I had a similar problem, which I fixed by reversing the ports used by the Deutch connectors at the back of the display unit. This was the only thing I changed after an unsuccessful hour with tech support. In my case it made the problem you described go away. Since then the unit has been very effective on my boat.”

      Hope this works for you.

      (Andrzej replied to the email comment notification instead of replying here, is why I got involved)

    • Jack,
      Andrzej is correct, the Deutsch-style plugs we use are very reliable, but if the sockets are not flush with the ends of the connector before snapping in the wedgelock, a bad connection can result. This can manifest itself as data that freezes, or reboots, etc. Please check both ends by using a screw driver to pop off the wedgelock. There is a video on the SG200 product page that show what they should look like. Make sure you seat the connector firmly in the SmartShunt – you can also try the other receptacle.

      Concerning the fixes, we have a bug in the current firmware that sometimes freezes the network after running for hours. If this is your issue, you can reset the network with an extra-long press on the display button. Just wait for the checkerboard pattern to show, then release.

      We have fixed this issue, and made several improvements that will be released soon — they are working their way though testing right now. For example the update times for the devices has been sped up 8x. We also have some new chemistries that will either be in this release of shortly after that make some noticeable improvements, more on these soon.

      My apologies for your troubles, we are working hard to make the Sg200 the best battery monitor out there, and I hope your view of it will change with these fixes we are rolling out.

      • Jack Ganssle says:


        Thanks for your speedy response. I will try your suggestions next trip to the boat.

        The roughly 1 second update speed was acceptable, but making it faster is a great idea.

        I’ll stand by for the next firmware update as I really want this to work. I had a LinkLite which had a terrible UI and the LCD was too dim to read.

        • Jack,

          You are welcome.
          To clarify, the update I was referring to was when upgrading the firmware, not the refresh speed of data on the network. We are keeping that speed at 1 per second for the foreseeable future, to help conserve power.

          • Jack Ganssle says:

            Just to close this out, the unit has been updated and now works great. Thanks for your help, Chris!

  46. Lasse says:

    Hi, I have finally installed my Balmar units and winter is over and the boat is in the water. It is an SG 200 + bluetooth dongle. I get contact with the Dongle on my phone and the display/whole unit freezes…

    There is no way to update the software, because a text, “Multiple devices of the same type with early firmware release detected. Only one of each device type is allowed on the network while doing updates of these early devices.”
    I have:
    BLUELINK v.2.56
    DISPLAY v.2.00
    BANK v.B.04
    How do I uppdate the firmware ?
    Anything else I should think of ?
    Thank you in advance for all help!

  47. For those that may run into the issue that Lassie had, here is a procedure you can follow to ensure a trouble-free upgrade:

    Original (First firmware release) devices can only be upgraded when there is one original device on the network at at time. This affects devices with the following firmware.
    DISPLAY v.2.00
    BANK v.B.04

    To upgrade, do this, after ensuring you have the latest app from the Apple or Google play store.

    1. Disconnect the SmartLink cable from the display at the SmartShunt.
    2. Plug the Bluetooth Gateway directly into the port you removed the cable from in step #1.
    3. Ensure that the BT gateway is the ONLY device plugged into the SmartShunt.
    5. Use the App to upgrade the Gateway, if it has an upgrade available.
    6. Upgrade the SmartShunt software.
    7. Plug the Display back into the SmartShunt, and the gateway back into the display (Typical configuration)
    8.. Upgrade the Display.

    You MAY need to pull the fuse between upgrading each device during this process.

    If you have more than one SmartShunt or more than one display, use the rule “Only one original device on the network at a time when upgrading.” and you will be able to upgrade all devices.

    This is a one-time issue, as long as you give each device of the same time a unique name, you will be able to upgrade them in place going forward.

  48. All,

    We just released APP version 1.5.1 onto both the Google play store and the Apple Store.
    This release addresses a few issues:

    1. Fixed miscalculation of Time Remaining when discharge was less than C/20.
    2. Corrected network issue causing APP to lose realtime data after many hours.
    3. Improved SoC accuracy when battery is fully charged with very low discharge rate (below 1A)

    There are no chemistry changes. When you update the SmartShunt, “New” Chemistries are loaded as well, but you don’t need to reapply, since they are actually the same. (Due to the memory structure of the device, we just always need to reload them into storage, even if they are the same.)


  49. Rick says:


    I’m 20 days into my switch from 1100Ah of Gels to 1200Ah of LiFePO4 dropins (4 x 300Ah).

    We had a MasterVolt shunt so decided to go with 2 MV 100A chargers and 2 MV 2500W inverters. The shunt always seemed to be accurate with the Gels, but is off with the LFPs, and I’m in discussions with MV about this.

    Am thinking of adding the Balmar SG200 as another point of reference. But I’m not sure if this makes sense and am looking for guidance.

    Our batteries are tucked under the berth, so a major PITA to get to with a multimeter. We have Midnite MPPTs with their Wizbang Jr shunt that is parked right beside the MV shunt. And the batteries have a BMS accessible via a bluetooth app. So I can cross check status, but the battery manufacturer suggested that I should still validate that data with a multimeter. So that led me to find the SG200 online and this thread.

    We also have 2 x Wakespeed WS500s without own shunts, but we are a sailing cat so engines are only only half the time.

    So does it make sense to add the Balmar to the mix.

    Right now, the Wizbang, BMS, and multimeter are somewhat in agreement that the batteries are Floating at around 13.48 – 13.5V… and the MV shunt is the outlier at 13.37V…

    Thanks, Rick

    • Make sure you take into account your overall maximum charging rate if you have LiFePO4 batteries and a bank that large. I have 800 amp hours and charge routinely at 400 amps. The SG200 shunt is only rated at 350 amps (see comments further up in the chain) but there was talk of a dual shunt version that could potentially solve this issue, although I don’t know if that is out yet….

      • Rick Kwasnicki says:

        Hi Steve,

        Thanks for the info. I only have 1,100W of solar, so at the very max I could charge at 90A. I hope to bump this up to 2,000W but that would not exceed 350A. My gen will use the two 100A chargers, and the Alternators are 125A each and will be managed by the Wakespeed WS500s, so potentially I could charge with alternators and solar, but the solar is set to go to rest if it senses another charge source.

        We have a 5000W inverter that could potentially discharge a bit higher though.

        My concern is where to fit the smart shunt in with the other two shunts. I have 3/0 cables from the batteries positive and negative going to the MV shunt, then the positive goes to the positive bus. The negative from the MV shunt goes to the Wiz Jr shunt and then to the negative bus. I read in another site that the smart shunt should be within 30cm of the negative coming off the battery bank. So that would put it before the MV shunt.

  50. If you are installing the SmartShunt in-line with other (not Balmar) shunts, the SmartShunt should be the very closest one to the batteries. This is because we are not just measuring current and voltage, but Impedance.

    We have walked back the “Strong suggestion” that the SmartShunt be within a foot of the batteries. Closer is better, all things considered.

    Is the Midnight Solar shunt only measuring the output of your solar? What would the function of the MV shunt be in the revised installation?

  51. Rick Kwasnicki says:

    Hi Chris,

    The Midnite shunt measures amps to feed to the Classic 150 MPPT to allow transition from Absorb to Float based on amps… I can set ending amps to something like say 6A… so when the MPPT sees the batteries only getting 6A, then it switches to Float. The MV shunt is similar, it feeds the chargers with something called Return Amps while they are in Absorb and it is a percentage of amps remaining to 100%, so if I set Return Amps to 4%, the chargers should go to Float when there are about 50A left to 100%. At least that is my understanding.


  52. Thanks Rick.

    Concerning Shunt ratings, We give real world ratings on the SmartShunt. We needed to do the testing as we have electronics in the SmartShunt itself, while most standard shunts do not. What I have found with a bit of sluthing is that those “traditional” Shunts are to be derated for continuous use. BleuSeas specifies a 20% derating. SAE standards support a derating of 33%, which is the more widely accepted standard.

    We have not yet implemented the ability to parallel SmartShunts to double their current carrying ability, but it is on the roadmap. We are working on some other improvements that have been asked for by a lot of users.

    Here is some verbiage: Power Rating/Derating. Because current shunts are resistors and dissipate heat from the current flowing through them, they get hot. Since that heat can change their resistance and even permanently damage the shunt, current shunts are often given a power rating or a derating factor. The heat produced is power measured in Watts (W)

    W = I² × R

    This says the heat produced increases with the “square” of the current. So doubling the current increases the heat power dissipated by 2² = 2 × 2 = 4 times. So small changes in current produce big changed in heating. Dealing with this heating gets complicated fast. In practice current shunts are often rated to be used continuously at only 66% of their “rated current”. So if you need a continuous 80 Amp measurement you can’t do it wth a typical 100 Amp ( thus 66 A continuous) rated current shunt. Alternately, a shunt may have a graph that shows how you derate its continuous current as a function of the surrounding air temperature. You might find you can use it at full current if it’s 0 °C around the shunt, but at only 40% of full rating with a 90 °C ambient temperature.


  53. Rick Kwasnicki says:

    Hi Chris,

    Thanks for the info. Do you have the dimensions for the shunt. We have a Lagoon 450, and Lagoon never envisaged major refits in the small battery cavity they built.

    From looking at various sites that sell the SG200, it looks like the SG200 kit is sold with the SG200-0100 shunt, but the Bluetooth Gateway needs to be ordered separately. Is that right? Is there any other component that needs to be ordered?

    The Wizbang Jr can fit onto other shunts. Its smarts are on a small circuit board that screws into the shunt. We got their Deltec MKB 500A shunt, as the MasterVolt shunt is not designed to play with others. From the looks of your shunt I don’t think the Wiz Jr circuit board will fit on to it.

    • Rick,

      I tried to connect a product that uses a generic Shunt to the SmartShunt, and it did not work.

      The SmartShunt is ~4.75inx3.25inx2in high (without connector – add another inch or so)


  54. Rick Kwasnicki says:

    Does anyone know if it is possible or if there are plans to connect the SG200 to a NMEA2000 network so I can get the SD data displays on my MFD….

  55. Rick,

    We are actively working on the development of a N2K enabled SmartShunt. It will retain one SmartLink port, ensuring compatibility with the existing color display and BT gateway. I cannot at this time state a release date.


  56. rick says:

    Hi Chris.

    I have ordered the SG200 kit which comes with the SmartShunt, and the Bluetooth Gateway… Will likely arrive in early August… slow boat to Tahiti…

  57. Steve Person says:

    Since my camper will be sitting in a hot garage in the summer, I will be removing my LiFePO4 batteries and keeping them in the house. Can you give my an idea of how the SG200 will react to being disconnected and reconnected from time to time. Also, what should I do to not lose accuracy doing this.
    Also, I couldn’t find the milliamp draw for the bluetooth gateway, if you could help with that I would appreciate it.
    Thank you, Steve

  58. Steve,

    Assuming your batteries have been learned, you will retain a surprising amount of accuracy with the SG200 when disconnected in the scenario you described. Don’t charge and then immediately put the fuse in. When you re-install, make sure there are no other loads/charging on the batteries when you put the fuse back in. Let it rest in that state for at least 30 minutes before putting a load on or charging. While you won’t see a SoH value immediately, the retained value is used. The value will again be shown once there is some cycling on the batteries. I don’t remember the exact ma draw, but I think is is only 1-2ma when idle, and one or two more when in use.

  59. Steve Person says:

    Hi Chris,

    Thanks for the help. So having the batteries SOC higher or lower than when they were disconnected won’t cause a problem when reconnected? Would it be better if the SOC was very close at disconnect/reconnect?

    Thanks for providing such good support for your customers,

  60. Chris Witzgall says:

    Assuming the batteries are learned, it should not matter where there SoC is when you disconnect or reconnect. The SG200 is simply taking a reading of the voltage and impedance at rest and comparing it to stored information, The only exception to that might be if you disconnect at 100% and reconnect at the same. Of course, this is not good for LFP batteries, you want to store them partially discharged.


  61. Andy Baird says:

    “You can indeed run headless without a display.” That’s good news, because I have no wish to mount yet another display in my RV. Like many of my friends who have been using Victron BMV-series monitors via Bluetooth, my SG200 dismay is lying in a compartment, unseen. All my interaction is via the iOS app.

    So, a question and a suggestion. First, is it as simple as disconnecting the display from the shunt and plugging in the Bluetooth gateway instead? And second, I’d like to see Balmar offer a Bluetooth-only “headless” shunt-plus-gateway kit. If you’re doing as I and my friends do, and only using the phone-based app, there’s no need to pay for the display.

  62. Andy Baird says:

    Uh, that should have read “my SG200 display”! I’m happy with the unit so far, after a week’s use.

  63. Andy,

    We are working on the SG205, which will package up a SmartShunt and the BT gateway, and forgo the display. The app as it stands need a few changes before we start to sell it, adding the ability to reset devices, alerts and faults, and a few other things. You can run headless right now, if you are ok with these limitations. Since your display is hidden away, I imagine you are.

  64. Anonymous says:

    Hi Chris, (if you are still here)
    I can’t get my bluetooth gateway to connect to my android phone. When I try to open the app, I get “Unfortunately, Balmar has stopped”. I do have location turned on on the phone, and I tried switching the plugs on the back of the monitor, but no luck yet. I should admit that I hate smartphones and the problem is likely due to me missing something.
    Thank you, Steve

  65. Ken A Heaton says:

    NMEA 2000 output : Looking at the 2022 Balmar Catalog on the Balmar website, on page 17, I see Balmar now have the SG2-0130 SmartShunt listed, along with a few other NMEA 2000 compatible adaptors, cables, and kits. A search of Balmar’s site for: “SG2-0130”, “SG230” or”SG235′ yield no results.

    A question for Chris: When does Balmar expect to be publishing information on these kits and their capabilities, and when does Balmar expect to be shipping the NMEA 2000 parts?

    • Ben Ellison Ben Ellison says:

      Hi Ken, I hadn’t noticed the 2022 catalog entry — thanks for that — but Chris told me last week that the N2K version of the SmartShunt is coming soon. I mentioned it in my first look at the MC-218 regulator, which already networks with the existing SG200 battery monitoring components:

      • Ken A Heaton says:

        Thanks Ben, We have an SG200 installation now, including the Bluetooth gateway and iPhone app, monitoring our two house banks along with the voltage on the engine’s start battery. I am very please with it. I’ve read Chris’s earlier posts mentioning the anticipated N2K integration so I’m glad to see it in their 2022 catalog.

        I’m looking at incorporating a Balmar MC-618, along with a new Balmar alternator and a serpentine belt installation into our sailboat’s changing system so thank you for the first look article on the 618.

  66. I think the SG200 is an amazing product (really product line), and I am very interested in it. I was lucky enough to talk with Chris at the Annapolis Boat Show a few years back.

    If you look at the most recent update to the SG200 software page … it looks like there are new additions … the SG230 (a SG200 network to NMEA2000 adapter) and the SG240 (a SG200 network to CANBUS adapter) which I am guessing is probably something like J1939.

    I have a number of questions about the SG200 and these 2 adapters still:

    1) The documentation for years has made reference to paralleling two shunts together if one needs to exceed the 350Amp continuous current. I was never clear if that was supported in software as of yet. Is it? (I know you can have multiple shunts.)

    2) The SG200 says it support 12 through 48 volts. If shunts are added at 24v or 48v, how are the SG2-200 Display and SG2-300 Bluetooth adapter powered? Unlike NMEA2000, does the SG200 network support voltages other than 12 volts? Are the display and bluetooth adapter capable of running at 24v or 48v? (Maybe it steps down the voltage from the battery to the network?)

    3) Following on from #2 … can you have multiple shunts for different battery packs running at different voltages running on the same SG200 network? (Example: A 24v primary house bank with say 1 or 2 shunts (if paralleling is supported) with a secondary 12v house “pony” bank with a shunt, used for 12volt only devices/loads? How is the SG200 network now powered … at 12v or 24v?)

    4) With the new SG230 NMEA2000 adapter …
    4a) Is this adapter a extension to the the NMEA2000 backbone? It must be stuck on one end of the NMEA2000 network and SG200 shunts, displays, bluetooth, and regulators, are now nodes on the NMEA2000 network? How is the BUS terminated? Does each device now have a LEN? Does the SG200 network need to be 12v only, to be compatible with the NMEA2000 network?
    4b) Is SG230 instead some how electro-isolated from the NMEA2000 network providing some sort of BUS-to-BUS translation and thus only looks like a spur device to the NMEA2000 network? How many LENs does it add to the NMEA2000 network in this case? I assume this would also allow the NMEA2000 bus to continue at 12v while the SG200 network could run at any voltage it choose to (12v, 24v, or 48v).

    Thank you for the clarification and maybe my confusion comes from a fundamental miss-understanding of how something operates.

    Thank you again, and I would be wondering if Ben E and/or Ben S might be doing a write up on the new SG230s.

    (PS: I posted a similar comment a few days ago, but it seemed not to post for some reason.)

  67. Matthew,
    Chris from Balmar here. The SG2-0130 SmartShunt is in the SG230 and SG235 kit. It can also be ordered seperately with that part #, if you only need the SmartShunt.
    These are the N2K versions. The other version is for RV-C networks, used in recreational vehicles. There is no “N2K adapter: the SmartShunt is a N2K device, Isolated as per the standard. Treat it just like any other N2K device. It does not provide network power. If you don’t power the network separately, the SmartShunt will not provide any N2K data.
    The SmartShunt itself is powered from the 12-48V source. This powers the Display and BT gateway, etc. The only thing that this does not power is the N2K network. Again, this is to adhere to the N2K standard.

    If you have an SG200 already installed, just order the SG2-0130 to replace the SmartShunt, and connect it to your N2K network.

    The LEN equiv. is 2. Presently, we only support ONE N2K SmartShunt on the network. This should change in a future firmware update, done via the BT gateway.

    We removed the wording from the Manuals about paralleling SmartShunts. The call for it has not been enough to support the development effort to make it happen.

  68. Ben,
    Right now you can only use the one SmartShunt on the network. We will support the instance # change in the future. The supported data points are Battery Voltage, SoH, SoC, Time Remaining, Battery Current. Config is only thought the BT gateway to start, but hopefully MFD mfgs will support the needed Data to configure the device.

  69. Rob P says:

    Chris, thanks for the N2K parameter info. Re reporting battery voltage, is this just the house bank? What about the aux battery voltages? If one has N2K access via a smartphone/PC/RPi/etc could a tool be provided to do the programming that way? I’m also familiar with RV-C and have done some extensive work with it on my motorhome, could you also elaborate what parameters are reported to that CAN if different than N2K? I’m looking for an RV-C battery monitoring solution that is independent of an inverter/charger like the Magnum with ME-RVC and the RV-C Smartshunt is a potential candidate. Thanks.

  70. Hi, you can read more about the PGNs used here:

    Note the instances of the aux voltages are = ( 2 x (this-1) + 5) for Aux-1 and = ( 2 x (this-1) + 6) for Aux-2. This is for both the RV-C versions and the N2K one.

    Programming the SmartShunt is only supported from the Color Display or the App/BT gateway at the present.

  71. Clay Greene says:

    Chris, I am having a problem with installation of the SG200 that Balmar Technical Support has not been able to solve. The display will not show positive amps, either from the battery charger or the alternator. It shows negative amps only, although the State of Charge will increase from 80 percent to 100 percent with the battery charger recharging the batteries. I have been told that I must have an alternate path to ground but have been given no assistance in addressing the issue (I have sent in photos and a wiring diagram of our system). The alternator is grounded directly to the engine block on a separate ground than the cable that runs to the house battery bank. The battery charger is grounded on the cable side of the shunt. Technical Support tested the shunt and said it is working properly. Can you offer up any ideas for how this issue can be resolved? Thanks.

    • Ben Ellison Ben Ellison says:

      Hi Clay, I don’t have Chris’s expertise but I have been messing around a lot recently with an SG200 and my two-bank, two-alternator system. I’m pretty sure you’ll find that there is a negative cable from your starter motor or block going either to the starter or house bank negative. It and the start-to-house negative should be on the system side of SG200 along with all other negative cable runs. Only the house battery negatives should be on the battery side of the SG200. Working for me, but also suggest diagraming the system.

      • Clay Greene says:

        Ben, you are exactly right. I got this same advice from two fellow Catalina owners this past weekend and moving the engine ground to the “cable” side of the shunt fixed the problem. Surprisingly, this is not addressed in the SG200 manual and the Balmar service technicians did not identify this as the problem even though I twice sent them a wiring diagram of our system that showed the engine ground running to the negative post on the house battery bank. Thanks for your help!

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