Charging 1 battery of 24v (2x12V)

[RaySE]

Quick question here: ( and yes I know it's wrong to do so but needed a bit of a quick McGuyver solution)

I have 2 large 12v lead acid batteries in series to get a 24v system. Due to circumstances I needed to supply extra power for my 24V application but only had a little 12v charger at hand. I connected that charger to one of the 2 batteries and started using the 24V hydraulic pump.
As said, I know you're not supposed to do so, but is it not true that if you charge 1 of the 2 batteries slowly, the 2 batteries start to balance ? I mean one can not really have a much different voltage then the other, not?
It wasn't a big ass booster charger pushing the amps in, just a small battery charger that goes to drip when done. Is it really that bad that I am damaging the batteries ? (Not planning on doing this to often )

Thanks for any replies

 

[sunshine_eggo]

Quick question here: ( and yes I know it's wrong to do so but needed a bit of a quick McGuyver solution)

I have 2 large 12v lead acid batteries in series to get a 24v system. Due to circumstances I needed to supply extra power for my 24V application but only had a little 12v charger at hand. I connected that charger to one of the 2 batteries and started using the 24V hydraulic pump.
As said, I know you're not supposed to do so, but is it not true that if you charge 1 of the 2 batteries slowly, the 2 batteries start to balance ?

It is not true. You are adding charge to one and subtracting from both. Charged battery will eventually get full if you leave the charger on long enough. Other battery will never gain charge. They will always diverge. If you are also charging at 24V, you are almost certainly going to damage the battery with the 12V charger on it.

Recommend:

Dismantle bank.
Charge battery 1 to 14.4V. hold for 4 hours.
Charge battery 2 to 14.4V. hold for 4 hours.
Parallel batteries, charge to 14.4V, hold for 2 hours.
Place in series for 24V

Get a 24V charger.

At an absolute minimum, charge both to full as 12V while the system is inactive.

 

[RaySE]

If you are also charging at 24V, you are almost certainly going to damage the battery with the 12V charger on it.

Thanks for your answer. So the 2 batteries will not balance out? Okay understood.
And No I wasn't also charging at 24V, because if so, I wouldn't need to charge at 12V at the same time.

Didn't have time for the recommended actions that is why I gave it the emergency solution. Must say it sort of did work, I know from experience the batteries were not up for the task I was asking, and still with the 12V charger on the one battery I completed what I had to do.
But I will get a 24V charger to be safe next time. (Probably a lot cheaper then damaging my batteries)
Thanks so far

 

[MisterSandals]

I connected that charger to one of the 2 batteries and started using the 24V hydraulic pump.

Having to do this in a pinch does not sound outrageous if the need was great enough. I would have alternated charging to the 2 different batteries and equal intervals. And even then, if i saw one battery falling behind, i would have increased the percentage of charging to that battery.

But of course this is all not recommended...

 

[sunshine_eggo]

Thanks for your answer. So the 2 batteries will not balance out? Okay understood.
And No I wasn't also charging at 24V, because if so, I wouldn't need to charge at 12V at the same time.

Didn't have time for the recommended actions that is why I gave it the emergency solution. Must say it sort of did work, I know from experience the batteries were not up for the task I was asking, and still with the 12V charger on the one battery I completed what I had to do.
But I will get a 24V charger to be safe next time. (Probably a lot cheaper then damaging my batteries)
Thanks so far

Doing things because you have no choice is just how it works out somehow. Important to understand the implications and how to undo the damage.

If the system isn't in constant use, simply charging each 12V to full individually while they're still wired in series is way better than doing nothing.

 

[pollenface]

Add a balancer or 2 for peace of mind.

 

[RaySE]

I would have alternated charging to the 2 different batteries and equal intervals.

Doesn't make it right but, would have made it a better solution. Will keep that in mind in case off....