Wiring for three 12 volt battery banks and solar mppt controller

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alchemyst asked Jun 26, '21

Wiring for three 12 volt battery banks and solar mppt controller

Is there an example wiring schematic anyone has that I could use to design changes to an existing system? The system has solar panels connected through a Victron 100/50 MPPT unit. The MPPT charges a house battery bank. However, there are two other banks - an engine start bank and a windlass/bank thruster bank. Right now those are only charged when connected to shore power or the generator or the engine is on. The engine has an externally regulated alternator that charges all banks. With both the shore power and the external regulator, the house bank is treated as the first bank but the second outputs are then divided by a battery isolator to charge the start and windlass banks.

So, with an example I think I could take it from there.

Thanks in advance

Tom

mppt charging

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Answer 1 · 2021-06-26T21:34:55Z

Mike Dorsett answered · Jun 26, 2021 at 09:34 PM

Hi, Unfortunately, you can't use a spliter on the output of an MPPT to charge multiple banks of battery. You can use an automatic charging relay,or the Orion dc / dc converters. For the ACR, you could look at the Victron Argo fet - and drive the energise input from the PV - with protection to ensure it does not go to too high a voltage! However, this would tend to charge one bank from another, so if the house bank was full and the winch battery low, current may flow from one bank to another. My be would be to use the dc / dc converters to float charge the starter and winch batteries from the House bank, and put all the charging into the house bank as priority.

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alchemyst commented · Jun 28, 2021 at 09:33 PM

Mike - thanks. I had been vaguely considering two echochargers, but you are right. At least one, and likely two, DC to DC converters would be best. I'm always wary of getting too complex in case there's an accidental "loop" somewhere in the ground that I inadvertently create (scared of corrosion in our saildrive). But, I'll sketch it out and make sure all looks ok.

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