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Old 26-06-2017, 17:04   #1
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Charging 24V Bank With 12V Charger

Hello CF,

I have two 24 volt battery banks, one starter and one house, both (2) 12V in series.

My recently installed Xantrex 3024 inverter/charger seems to be not functioning correctly.

The Xantrex unit charges my house bank and an Echo-Charge unit level charges the starter bank.

Until I can deal with the Xantrex unit I am using my manual 12v charger to charge both banks. I was disconnecting the cable between the two batteries to make them stand alone 12v to charge. Today when I was checking the 24v battery voltage with my DVM to compare to the digital readout on the DC panel I noticed that by checking the pos and neg on each battery even thought they are still tied to together to make 24v I get the 12v readout.

I hooked up my 12v charger to the pos and neg on one battery and the panel voltage went up from 23.3 volts to 24.7. The battery is pulling 14 amps from the 12v charger.

Is this ok to do? It would save me from taking the cable between batteries off to charge, but I don't want to damage my $2000 battery investment.

Thanks,
Jeff
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Old 26-06-2017, 17:10   #2
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Re: Charging 24V Bank With 12V Charger

In my Bassboat my charger has 4 12v leads 1 each for the 2 in 12 series, Ie 12 v to 12 v battery, I then have 2 12v to my start to get the amperage up to 30! This per bat mfg. My 37 sailboat has 2 12v in series, with 2 individual 12v leads from the charger! It's been set up like this since the 80s.
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Old 26-06-2017, 23:01   #3
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Re: Charging 24V Bank With 12V Charger

The problem is you will never charge both the same amount. And the balance will permintaly be out of whack. You need to put them in series and charge both at the same time with the charger. So both are equal.
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Old 27-06-2017, 06:23   #4
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Re: Charging 24V Bank With 12V Charger

You mean in parallel, as per the OP request. Unless he gets a 24V charger, which would be ideal.

But really, a good quality adjustable charger that actually gets each battery to 100% Full will do so consistently, Full is Full.

Key would be no Loads on any, until all are charged.

But paralleling them will be faster and easier than doing each sequentially.
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Old 27-06-2017, 09:12   #5
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Re: Charging 24V Bank With 12V Charger

Quote:
Originally Posted by Mikado View Post
Hello CF,

I have two 24 volt battery banks, one starter and one house, both (2) 12V in series.

My recently installed Xantrex 3024 inverter/charger seems to be not functioning correctly.

The Xantrex unit charges my house bank and an Echo-Charge unit level charges the starter bank.

Until I can deal with the Xantrex unit I am using my manual 12v charger to charge both banks. I was disconnecting the cable between the two batteries to make them stand alone 12v to charge. Today when I was checking the 24v battery voltage with my DVM to compare to the digital readout on the DC panel I noticed that by checking the pos and neg on each battery even thought they are still tied to together to make 24v I get the 12v readout.

I hooked up my 12v charger to the pos and neg on one battery and the panel voltage went up from 23.3 volts to 24.7. The battery is pulling 14 amps from the 12v charger.

Is this ok to do? It would save me from taking the cable between batteries off to charge, but I don't want to damage my $2000 battery investment.

Thanks,
Jeff
I don't see it as a problem. Just don't forget to charge both so that one isn't topped off and the other is down. The charger is isolated so removing the cable shouldn't be an issue. JMHO
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Old 27-06-2017, 11:20   #6
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Re: Charging 24V Bank With 12V Charger

As long as there is no 24v circuit, i.e. the batteries are still conencted in series BUT nothing else is connected across them, yes, you should be able to charge each one, one at a time, from a 12v charger.

That's not ideal because as mentioned, the odds are they will not be identically charged, but in the short term, that will sort itself out, the same way that any two "slightly different" batteries would sort themselves out. So yes, OK for the short term, especially if you are patient and try to get them reasonably matched.

Hopping around to changer wires all the time...Gonna be incentive to get the big one fixed.(G)
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Old 04-07-2017, 15:54   #7
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Re: Charging 24V Bank With 12V Charger

The Trollbridge24 will charge both batteries from a 12 volt source. It puts the batteries in parallel for charging and switches them in series automatically when a load is applied.
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