Does combining sevaral types of batteries could damege the batteries

[mad_lad9676]

I have three lead acid 12v batteries (1 car battery, 2 ups batteries). I want to create a 24v pack by connecting 2 ups batteries in parallal and then connecting car battery to that in serial. could that damege the batteries 

[Kilrah]

-> Moved to Hobby electronics

 

Parallel is not an issue as long as they're at the same state of charge when you connect them, but once you put batteries in series and they're unmatched you need to monitor them to stop charge/discharge should one get full/empty before the other.

[mad_lad9676]

1 hour ago, Kilrah said:

-> Moved to Hobby electronics

 

Parallel is not an issue as long as they're at the same state of charge when you connect them, but once you put batteries in series and they're unmatched you need to monitor them to stop charge/discharge should one get full/empty before the other.

So what you mean is I should not put different capacity batteries in parrallal right

[Kilrah]

In parallel it's fine, but not in series.

[mariushm]

Car batteries are optimized for very high current discharge, short bursts. Basically they're optimized to handle starting the car motor, when you crank it.

 

UPS batteries are optimized towards continuous low current draw, as in taking power for 5/10/30 minutes from them and not multiple bursts of 10-30s you need to start the car.

 

So it's not quite a great idea to mix them, the car battery could discharge a bit faster and then take in power from the other battery to charge itself up, so you just waste power moving energy between the batteries.

 

If you need more voltage, you put the batteries in series.

IF you need more capacity (run for longer time at same 12v voltage) then you connect the batteries in parallel.