Upgrading to lithium batteries & testing an all Mastervolt DC power system

Ben Stein

Ben Stein

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

29 Responses

  1. Eric Artman says:

    No solar/wind generation?

    • Ben Stein Ben Stein says:

      Solar is on the list for upgrades. However, I don’t have too much hope of getting the boat to be able to generate all her power from solar or wind. The boat draws enough, primarily because of refrigeration loads, that I doubt I can get enough solar to make all the power I draw.

  2. Carter says:

    Do you still have a separate Lead Acid starter battery?

  3. Charlie McVey says:

    Very interesting Ben. I would like to install Lithium on our next boat possibly.

  4. Gary Warner says:

    Hi Ben – I’ll be very interested in your installation and operating experience with your new high capacity alternator. I did an alternator upgrade 4 years ago to a 180A small case unit with external mounted diodes powered by our Yanmar 6LY2A-STP engine with new pulleys and 10 rib serpentine belt. Our initial install was somewhat problematic as the belt occassionally rode over the water pump pully. Numerous alignment attempts did not solve the problem. Finally the alternator bracket was removed, bolt hole slotted and with the addition of a idler pulley hopefully resolved. So exact pulley alignment is critical and addition of an idler pulley necessary to maintain belt tension. I think a major contributor to the belt overriding problem, along with imperfect alignment, is the low shoulders on the outer ridges of the Balmar replacement pulleys which allowed the belt to easily ride over thos outer ridges. The alternator pulley has higher shoulders and we have never had an override at that pulley.
    I hope your pulley replacement kit has better designed pulleys as that should make for a smoother transition. I’d also seriously consider a spring loaded idler pulley if you have space. We did not and are using a fixed pulley.
    We have eliminated the need for a generator on our boat with the 180A alternator, 400 watts of solar panels and 4 Firefly carbon foam 100 Ahr house batteries. While not year round livaboards, we do cruise our Ellis 36 for 6 month seasons with 2-3 months summer cruise to Maine each summer.

  5. Tim Connolly says:

    Hi Ben,
    Just curious if the Mastervolt system has NMEA2K interface or some other output that would allow for feeding various “power parameters” into a signalK server. I will need to replace my similarly aged Xantrex inverter soon and this will be an important feature so I can consolidate data in one place or on multiple displays around the boat that are being driven by the SIgnalK/Influx/grafana setup.

    Thanks for a great article

  6. Jeff Pernick says:

    Hi Ben. I like your focus on generator time as a game changer. That is exactly the phrase I have used. We are a 24 volt MasterVolt system with (2) Mass Combi and (2) Ultra 25/5000 180AH batteries. On Generator, both chargers run full blast and replenish 24 hours heavy battery use in about 90 minutes.

    And, just wait until you start messing with the power sharing features available for A/C loads. When you have the ability to use batteries to cover short term high amp draws like microwave or coffee maker, it’s just incredible how little amps you need from shore to run and charge the boat. You only need to provide for average load from shore, not peak.

  7. Ben Stein Ben Stein says:

    Mastervolt makes a MasterBus to NMEA 2000 adapter. This has the ability to output almost any of the parameters from MasterBus to NMEA 2000.

    I’m planning to cover those capabilities in a later entry, but here’s a panel from Grafana through my SignalK server:

    Grafana Panel

    -Ben S.

  8. Hamish says:

    I have a Mastervolt installation on my sailing catamaran and I love it. My goal is to minimize battery charging from the alternator as I like the peace of running the boat from solar. In this scenario, I currently have just over 1kW of solar and I plan to increase that to nearer to 2kW and what I have learned from trying to switch to solar power is that you must be able to take all the amps you can get when the solar panels are working at their maximum output. My current panels peak at about 80A@12V when the sun is bright and overhead, so I am hoping that my additional panels will increase this to around 150A. Lithium is also a key contributor to weight reduction, which is a hot topic on a sailing catamaran. If all goes to plan, I think I will be able to run my water maker (12V dc, 60A), my two fridges, the small chest freezer, all the navigation gear, washing machine, USB charging for personal devices, lighting etc without ever needing to start the engine to charge the batteries except in cases of extended overcast weather. With the current solar, I can operate in sunny conditions at anchor (we spent three months in a marina in Ecuador where the shore power was very sketchy and we never once needed to do anything to run the boat, but once I start all the navigation gear and autopilot, the system cannot keep up and it can’t handle anything other than very sunny conditions, so I hope that the extra capacity will increase my options and allow me to sail 24/7 without needing to start the engines (I don’t have a generator or AC).

    Looking forward to the rest of your comments about your new system.


    P.s. although it’s quite user unfriendly, the Mastervolt MasterAdjust software is very useful and provides detailed system control.

  9. Yianni says:

    I am wondering if the Mastervolt system has the ability to charge the batteries bases on in/out going current. Not just voltage.

    • Ben Stein Ben Stein says:


      I’m not exactly sure what you mean by in or outgoing current. Batteries accept charge based on their state of charge and the incoming voltage. I don’t believe it’s possible to control the battery cells and tell them to accept more charge at a lower voltage.

      -Ben S.

      • Yianni says:

        Ben, hi
        I think we are both describing the same issue. What I meant to say, up to this point Charging regulators were able to charge batteries based on voltage alone. Recently though companies such as Wakespeed (WS500) have been able to monitor and adapt the battery charging cycle based not only on voltage alone but on the current measured at the battery level.

        • @Yianni,

          Yes, the Mastervolt system is able to do this. With the Lithium batteries you don’t need a shunt as the battery BMS has a built in current measuring system. With non-Mastervolt lithium or any brands traditional batteries you need a MasterShunt.

          With the shunt connected to the charger or charger controller via MasterBus the charging is based on net current into and voltage at the battery, not what is measured at the charger source.

          This is not new: my boat has had it since 2010 and the tech has been available since the mid 2000s.

  10. Yup,

    The integrated nature of the Mastervolt system really works well. The battery tells the charge controller when to stop charging and when to reduce charging. Beautiful.

    • Mart says:

      I cannot find any documentation on this “telling the charge controller when to stop charging”. Do you configure “events” on the masterbus? Or is the Shunt on its own trotteling the charger when SoC reaches 100%?

  11. Joseph Pica says:

    Hey Ben, did lfpo4 13 yes ago with twin victron multiplexes that would charge my bank at 240 max amps. All reduced my genset run time to < 1/3rd from year before. All good. The multipluses had 4 programmable relays and customizable charging profiles. Offer power match supplementing of meager shore power.. which permitted us to cruise in comfort when glomming inadequate power from a garden out or other 15 and source. All cutting edge at that time. I am still a fan but know little about what Mastervolt offers. Currently doing that to my small boat however using Firefly batteries as did know how to control the outboard charging systems. Interested to see the comparison with Ben E. Warmest regards, to you and family, Joe Pica

  12. rareskyfive says:

    Amazing thanx for sharing information.

  13. Keith says:

    Hi Ben,

    I see in your diagram that you don’t have any lead acid batteries as buffer batteries.

    I was told by Mastervolt that you still need these. Was he mistaken? or was it just left out of the drawings?

    • Ben Stein Ben Stein says:

      Sorry Keith, it’s only six months later but I’m finally responding.

      In house uses I’ve never heard talk of buffer batteries in the mix. I am wondering if yours was a starting role? Or if the buffer batteries were suggested for alternator charging with an unregulated alternator?

      I’d be curious to hear more and better wrap my head around hybrid battery bank designs.

      -Ben S.

      • Keith says:

        Hi Ben,

        Yes a late reply indeed. Better late than never I guess.

        Anyway yes I was talking about the alternator charging. Yes it’s usually recommend to use buffer batteries to absorb possible voltage spikes that could potentially destroy the alternator should the lithium batteries suddenly open circuit due to the BMS activating it’s protections.

        The general recommendation is,
        Alternator ~> Lead Acid Battery ~> Charge Relay or B2B Charger ~> Lifepo4 batteries, which is ok if the starter batteries are the same voltage as the house batteries but otherwise it somewhat defeats the purpose of installing lithium if you also have to install extra lead acids.

        Victron have recently approved the Wakespeed WS-500 regulator for charging their Lifepo4 batteries without buffer batteries with the future possibility of Can-Bus connection. When I saw your diagram I thought perhaps Mastervolt was doing something similar with the Alpha 3.

  14. Abel Vazquez says:

    Thanks for sharing. I have purchase the same MasterVolt inverter charger because of it 160AMP charger and I will be using it ith non-Mastervolt lithium.

  15. Jan Flens says:

    A bit late to the party but i hope you are still monitoring this thread, we have two Mastevolt Lion 24/5000 batteries on board. All great, problem occurred when shorepower failed and we were not able to visit the boat for a long time during lock down. The batteries charge went down to 13% and has been reset by the dealer. We are experiencing much reduced times between charges suggesting the low charge level has impacted battery performance. Could that be the case you think and can this be reversed in hour opinion ? Thanks. Jan

    • Ben Stein Ben Stein says:


      This sounds like damage might have been done to the cells resulting in less capacity. But, I’m sort of surprised that noticeable damage would have been done to the batteries from a single discharge to 13%. Do you know how long the batteries were held at this state of charge?

      Also, have you been in touch with Mastervolt? There’s quite a bit of data that can be read from the batteries and the BMS and I would expect you could gain some clarity about the health and operation of the batteries from that data.

      -Ben S.

  16. Paliswe says:

    I have some concerns about the alternator and the belt used. When the generator produces 200A at 12V it’s equivalent to a load of 2400W = 3,22 horsepower (HP).
    From the picture of the alternator I can see that a v-ribbed belt is used and they are usually not able to transfer more than 1,5 – 2 HP. Using them at this high loads will wear them out very quickly.
    A recent installation with litium batteries was made on the Swedish sailing boat Ran II, currently on its way on the Biscaya Bay, France. They installed Lithium batteries this summer in Sweden, half the capacity of what’s described here. From Sweden they sailed through the Kiel Canal and when in France (English channel) the alternator belt had to be replaced. In this case it was a v-ribbed belt.
    To avoid to replace belts a couple of times every season, tooth belts should be used. Hyundai and Solé uses tooth belts that has better performance and last longer than v-ribbed belts. They are much thinner and since they have teeth they doesn’t need to be tightened so hard.

  17. Butch Davis says:

    Are toothed pulleys required to avoid belt slip with toothed belts? Belt slippage should be less with greater contact area, V belts, than ribbed belts, or not? A properly fitted V belt in pulleys in good condition properly adjusted should be virtually slip free. If belt driven loads are causing slip pulley size should be examined.

  18. Joseph Pica says:

    Butch we went to a microgroove pully (Balmar Altbelt serpentine system) to eliminate our belt slip. Before had one v belt which was adjusted properly however would slip badly under the load of our lfp04 bank demand on our Yanmar 100amp alternators. Overtightening on ours would have side loaded the fresh water(antifreeze) pump and raw water pump bearings causing premature failure and leakage. That load was on the top edge of what a single v belt can take.

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