Installing and configuring a Victron battery monitor

Ben Stein

Ben Stein

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

19 Responses

  1. Kevin Shea says:

    I have been extremely happy with the smart shunts on my boat. After converting the entire boat to ChargeX lithium, I installed 3 shunts; one for the stern thruster, one for the 2 battery house and starter bank, and one for the 2 battery bow thruster bank. I connected the starter battery lead to the second battery in each of the 2 battery banks so I am able to monitor each of the 5 batteries individually. The BMS that is built into each battery does an excellent job of balancing charge level. I never see a resting voltage variation of more than 0.02 volts across the 5 batteries. I don’t have a dedicated display but use the bluetooth app on my iPhone. Great product.

  2. Bruce C Pappas says:

    Do either of the companies interface with Raymarine?

  3. Petar Maksimovic says:

    Thank You Ben on a wrap up of major settings and most common source of errors on battery monitoring!

  4. Tom says:

    Good article.
    I currently have a Victron system including the BMV 712. Having read a number a write up’s of the Balmar SG2000, you gave it a positive review awhile back. I have wondered if the SG2000 might have been a better choice for me?? Also I never quite figured out how to incorporate into the VIctron system. Wouldn’t the Balmar’s self learning provide an easier option as opposed to the Victron calibration requirements?
    I am interested in hearing the opinions.

  5. Don Gulliver says:

    Since all lead acid based batteries lose capacity over time, how should this be accounted for when using a classic ‘coulomb counter’? If the discharge floor is 50% of rated capacity when new, this means the battery is being over discharged as it ages. How much should the original rated capacity be reduced each year to avoid this?
    As I understand it, the Balmar monitor is supposed to do this automatically?

    • Ben Stein Ben Stein says:


      The best answer I know of is also highly impractical. That is, periodically do a proper 20-hour rundown test to measure the actual capacity. In the real world, it is at best impractical to remove a house bank just to capacity test it. Plus, most boaters lack the tools to do a load test. So, instead, you’re going to be left to infer. With lead acid batteries, I set house capacity below placard capacity on day 1. That helps account for initial capacities that are often below the rated capacities as well as beginning to compensate for some age and use related capacity reductions. Over time, I will drop those numbers by 5 to 10% percent per year.

      -Ben S.

      • Don Gulliver says:

        Greeting Ben,
        Yes, a true capacity test is somewhat impractical. Though, if we had the right piece of test equipment we could leave it overnight (or more) if necessary. Any suggestions on a constant current loading device?
        We have been using that same derating factor as well. It leaves our clients a bit uneasy to think they’ve lost as much as half their bank capacity in 5 years. Especially on a light to moderately used battery bank. We recommend that in addition monitoring the daily Ah consumption, they check the voltage as well. Usually in the morning, before a lot of intermittent loads are in use (via inverters for example). A slow decline in voltage at a given Ah SOC seems to be a good indicator the batteries are nearing end of life.
        Was I correct in saying the Balmar BMS is supposed to determine remaining capacity in determining the %SOC displayed?
        I have been a reader of this blog for many years and consider the level of discourse on par with articles from magazines such as Professional Boatbuilder. Thank you and the other for their continuous effort in delivering top-quality information.
        Don G.

        • Ben Stein Ben Stein says:


          I use a Rigol capacity tester as a primary battery capacity tester. It’s designed for use on a test bench and somewhat large. I also have an East Tester ET5410. It’s a cheaper and smaller tester without the same level of precision (and a really painful user interface) but it does a fine job of measuring rough capacity.

          Without a purpose built tester, you can use any steady state load, like an incandescent light bulb, and do the math based on the usage of the load. The trouble is it can be tough to get to exactly the 20 hour rate.

          -Ben S.

  6. Gilli says:

    I installed both a Victron charger/inverter and a Victron battery monitor last fall. The company I bought parts from preprogrammed the charger/inverter for me (but I have the USB unit needed to change it myself). I’m wondering if how they programmed it and how I programmed the battery monitor will create any issues. I have a house bank of 4 x 110 amp hr batteries. I also have a 110 ah starting battery, and a 110 ah thruster battery. There are ACRs between the house bank and each of the starting/thruster batteries so that they receive a charge via the charge going to the house bank. When I explained that set up to the company that sold me the Victron, they set the battery capacity to 660 ah. When I set up the capacity for the battery monitor, which is monitoring only the house bank, I set it to 440 ah. Any issue with that inconsistency between the charger/inverter and the battery monitor? Anyone think the charger/inverter capacity should be set at 440 amp hrs?

    • I think you must have a Quattro inverter/charger – at least that’s the only model of Victron inverter/charger I could find that seems to offer a “battery monitor” function, with associated battery capacity setting. The inverter/charger uses this to provide a rudimentary State-of-Charge (SOC) value for the bank – but if you have an installed Battery Monitor, it is my understanding that the various systems that use or display SOC will ignore the value from the inverter/charger and utilize the one from the battery monitor instead as it is much more reliable. (At least my Cerbo GX instruction book says that 🙂 ) My feeling is that you could turn the battery monitor feature in your inverter/charger off – but I will defer to others who might have direct knowledge!

  7. Gilli says:

    Thanks for that suggestion, Harley. My inverter is the Multiplus 2, but I think it is like the Quattro in that it has an internal SOC value. But not a great one. I think that setting is off. I will double check. But it might explain why the Victron dealer programmed it as they did. I appreciate your post. Thanks.

  8. Paul George says:

    Ben…..excellent explanation.

    I did not see any explanation of the charge efficiency factor ??

    I figured it the hard way but this verified my understanding… I have the a 900 amp bank of Kilovault HLX batteries and one test I did was set the charged voltage very high so the shunt did not reset and then subjected the batteries to 4-5 days of the same load cycles.

    Monitoring the shunt voltages and current, I could easily observe the accelerated voltage ramp from ~13.6v up to ~14.1v and the current fall off at the same time so I know they were full each day.

    What I could then observe was the SOC state (calculation) cycling and declining each day about 5-6%

    I then adjusted the peukert exponent and the charge efficiency factor to optimize this response. It is not perfect but it is now 2-3%

    Together, these two constants affect the calculated SOC decline and recovery slopes (if I understand correctly).

    • Petar Maksimovic says:

      I’ve noticed the same using Victron Smart LFP, seems like Peukert value of 1.05 is not precise enough. Instead of playing with Peukert value, I set up charged voltage back down to 14.2, now Smartshunt resets itself to 100% correctly.

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