Mixing different battery sizes? Same voltage.

[WillAK]

I have 5x lead acid 12v 245ah batteries, each of which have different capacities. Some are older than others, and some have been used more.

I did a discharge test on each individually and they are all different:

B1: 1285wh
B2: 1214wh
B3: 715wh
B4: 645wh
B5: 645wh

My question is, can I put 4 of these cells together in series/parallel to 24v and get 3859wh? Or will the lowest battery cause problems once its full?

I don't want to damage the batteries further, but as soon as my LifePO4 batteries arrive they will be useless anyway, I just need something to last me until they arrive.

 

[SamDeleted]

My question is, can I put 4 of these cells together in series/parallel to 24v and get 3859wh? Or will the lowest battery cause problems once its full

You will get the sum total of 4x the lowest batteries capacity, so 4x 645 = 2380

(At best!)

B1: 1285wh
B2: 1214wh

Youd probably get better results with just these two batteries in 2s for 24v , 2499wh capacity

 

[WillAK]

You will get the sum total of 4x the lowest batteries capacity, so 4x 645 = 2380

Yeah that's what I thought.

Youd probably get better results with just these two batteries in 2s for 24v , 2499wh capacity

Ive currently got the 2x larger batteries together. But the others are just being wasted.
If that's the case then these two would be 2x lowest @ 1214 = 2428wh total?

 

[SamDeleted]

If that's the case then these two would be 2x lowest @ 1214 = 2428wh total?

Hahahaha, yes , of course you are correct !

 

[SamDeleted]

B3: 715wh
B4: 645wh
B5: 645wh

3p for 12v ? Separate little system?

 

[WillAK]

3p for 12v ? Separate little system?

Yeah that's what ive done. I have 3 separate systems. But that means 3x inverters and I have to run extensions and battery chargers to keep them topped up. It's a pain. So I wanted to just stick them all together to make things easier.

 

[SamDeleted]

Yeah that's what ive done. I have 3 separate systems. But that means 3x inverters and I have to run extensions and battery chargers to keep them topped up. It's a pain. So I wanted to just stick them all together to make things easier.

?. I know that feeling