Help with charging 2 batteries from 1 charger

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Jake Kennedy asked Feb 24, '21

Help with charging 2 batteries from 1 charger

Hi this may be a stupid question but I'll ask it anyway. A customer has come to me with a victron 230v 3 output 30a 12v charger. He has a bus with 2 12volt agm batteries. They are wired in series for 24 volt but he also has a 12 volt system so he takes that from one of the 2 batteries. I know this isn't ideal but it's what he has. My question is can I wire up each battery to 2 of the outputs on the charger? Will this charge each battery individually depending on individual voltages or will it put the same voltage to both? Is this the best way to do it as one of the batteries gets discharged more due to it supplying 12v as well as the 24v in series. Any info would be great.

MPPT Controllers charger battery

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Answer 1 · 2021-02-24T21:59:34Z

wkirby answered · Feb 24, 2021 at 09:59 PM

This would short circuit the low side battery via the charger because the negative would be common inside the charger.

We'd never advise anyone use a system that causes one or more batteries in a series connected string to become unbalanced.
However, the only way I can think of that might work is by using two separate isolated chargers.
The PSC IP43 3 output models have isolated outputs. However, this won't charge the batteries separately, the charge algorithm is common. So the batteries will still be out of balance.

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Jake Kennedy commented · Feb 25, 2021 at 03:18 AM

Hey Thanks for getting back to me so quickly. yea i figured this might be the case. by the time he gets 2 separate chargers for each battery he would be better off getting a third battery that is 12v only and a 24 v charger for his other 2. That will clean his system up better anyway and give him more life out the batteries. thanks for your info

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