Does connecting rechargeable batteries in parallel balance their voltages?

Thread Starter

abdulwahab.hajar

Joined Jun 14, 2016
93
So, I was thinking about cell balancing of LiFePO4 cells.
and when things are connected in parallel they have the same voltage right? So what would happen if we were to take two unbalanced LiFePO4 cells, say one with 2.8V and the other with 3.2V and connect them in a parallel configuration?
Would they balance each other out? as in giving us 3V in each cell after a while?

I mean could considering a mechanism which charges cells in parallel, and reconfigures them to be connected in series during charging be possible?
Would such an idea be theoretically implementable? Furthermore, would it be dangerous?
Thank you
 

ian field

Joined Oct 27, 2012
6,539
So, I was thinking about cell balancing of LiFePO4 cells.
and when things are connected in parallel they have the same voltage right? So what would happen if we were to take two unbalanced LiFePO4 cells, say one with 2.8V and the other with 3.2V and connect them in a parallel configuration?
Would they balance each other out? as in giving us 3V in each cell after a while?

I mean could considering a mechanism which charges cells in parallel, and reconfigures them to be connected in series during charging be possible?
Would such an idea be theoretically implementable? Furthermore, would it be dangerous?
Thank you
You have to be careful about battery chemistry. Lithium is frequently packaged in serial/parallel combinations, lead-acid - probably OK. - nickel chemistry usually dies in parallel.

As crutschow points out; uneaqually charged cells introduced together will pass current trying to balance - most types can't be charged as fast as discharged, so the results could be unfortunate.

New off the shelf cell are probably safe, but if the respective state of charge can't be predicted - join the + terminals with a current limiting resistor, leave it to balance for a while before soldering the strap across.
 
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