Some battery questions

[KenQuek]

I have 2x 12v5Ah and 2x 12v7Ah batteries. Can i hook them up in parrallel so i get 24Ah?

But when its in use, the 5Ah pair will get drained off first right? Most important is whether it is safe?

I did that with small cap batteries, but this time involve of high voltage and current. Better ask first.

[X34]

I have 2x 12v5Ah and 2x 12v7Ah batteries. Can i hook them up in parrallel so i get 24Ah?

But when its in use, the 5Ah pair will get drained off first right? Most important is whether it is safe?

I did that with small cap batteries, but this time involve of high voltage and current. Better ask first.

Assuming all 4 batt are in good condition, u should cal the total Ah based on the lowest Ah cell capacity . In this case, 5Ah x4 = 20Ah.

The cells with higher voltage will charge the lower voltage cells, so it would balance itself. If your current draw is greater than 1C, the balancing will lag.

[KenQuek]

Thanks mod for the explaination.

By the way, the two 12v5Ah are measured 13v+ while the 12v7Ah are measured 12.6v only. All are fully charged.


Is it still alright to put them in parallel?

[X34]

U r welcome.

As u parallel them - the higher voltage cells will charge the lower voltage cells till they are in equilibrium.

Remember to charge the cells immediately after use.

Check out this thread regarding SLA

http://www.daddyhobby.com/forum/showthread.php?t=7866

[KenQuek]

U r welcome.

As u parallel them - the higher voltage cells will charge the lower voltage cells till they are in equilibrium.

Remember to charge the cells immediately after use.

Check out this thread regarding SLA
http://www.daddyhobby.com/forum/showthread.php?t=7866

Yes i read that while searching before posting.

Actually the device is a UPS, wondering what will happen if i mod it.

Original is 2x 12v5Ah in series=24v

Planning to make it 2(2x12v) series parallel. or even 3(2x12v). Don't know UPS can take it or not. haha

I'm doing it cuz i'll be connecting a full tower PC with many devices along.