An MPII is much more than just a battery charger, and you wouldn’t even be using many of its features, despite having paid for it. Wouldn’t a simple battery charger powered by the generator be a better solution? The charge level should be accurately recorded in the Venus OS via a smart shunt.
It’s not exactly cheap, but Victron also offers something like that: the Victron Energy Skylla-TG 48/50 charger.
Yes, I know about the TG 48 (i have one) charger, but the problem is that it pulls all its power from only one phase of the generator. My generator doesn’t like that, because it is a three-phase generator and the load becomes unbalanced.
Also, the price of a TG 48 is much higher than the price of a MultiPlus, so using three MultiPlus units is actually cheaper for me.
Oh yes, but you can buy chargers from other manufacturers which are much cheaper than a MPII.
So you would need three cheap 48V LFP chargers. A 48V/20A charger would cost you not more than 150 €
Yes jou are richt, I originally thought it would be cheaper and more efficient to combine all six MultiPlus units into one system. When I started the project, I assumed it would be a straightforward setup. But as I went along, I discovered that things were not as simple as I expected.
I bought the three MultiPluses second-hand from someone who turned out to have purchased a system that was too small for their needs. At the time, I also thought it would be convenient to have a complete extra set, so that if anything ever went wrong with my other three MultiPluses, I could easily switch over to this backup set.
Looking back, that also turned out to be not as easy as I imagined. Integrating everything into one system and keeping it compatible requires a lot more work and precision than I initially thought.
But for now I’m keeping both sets separate. You can configure very good safety protections in a MultiPlus, and they can be controlled remotely as well. Since I already have them, and they weren’t very expensive, it still makes sense to keep them. One of the three units is even a GX model, so I don’t need a separate Cerbo either. and i have learn a lot
Hello everyone,
I would like to share a technical idea related to charging a battery bank from a generator. This approach is based on methods I have seen others use with smaller automotive alternators, and in principle a larger 230 V AC alternator should not behave fundamentally differently.
The idea is to use a high-voltage MPPT as the charge controller between an AC generator and a battery bank (for example, a lithium system). The generator output is first converted from 230 V AC to DC using a full-bridge rectifier and a smoothing capacitor, creating a DC bus that can be connected to the PV input of the MPPT. The MPPT then regulates voltage and current to safely charge the battery bank.
Since MPPTs are commonly used to regulate power from variable DC sources, and automotive alternator setups already apply similar rectification and regulation concepts, this method should theoretically be viable for a higher-power 230 V AC alternator as well.
The system has not yet been fully tested in my setup. However, given the similarities with existing alternator-based solutions, I see no fundamental reason why this approach would not work, provided that voltage, current, and power limits of the MPPT are respected.
Further considerations include managing generator load changes and possibly ramping up the MPPT power draw gradually (for example via Node-RED) to avoid sudden load steps.
This is currently a conceptual proposal, and I am interested in feedback or discussion from others who may have experience with similar configurations.