I am attempting to build a simple DC circuit that runs with 4 x 18650 li-ion cells. I would like this circuit to run in a series configuration to drive an audio amplifier, but then switch to four separate parallel circuits for individual cell charging. As an electronics noob, the only solution I have come up with so far is to have 4 DPDT switches manually switched. There would be a 4 cell battery protection board for series operation, but not when parallel as each cell will be isolated. There must be a much more elegant solution to achieve this? Thanks!

 

Since you already have a protection circuit for serial operation , the obvious way to do this is to leave them serially wired and charge all together in series . No need to disconnect anything , just have a socket which allows the connection of a 18 to 30V supply to charge . The protection circuit will keep the charging within correct limits , and terminate charging when cells are full and balanced.

 

Since you already have a protection circuit for serial operation , the obvious way to do this is to leave them serially wired and charge all together in series . No need to disconnect anything , just have a socket which allows the connection of a 18 to 30V supply to charge . The protection circuit will keep the charging within correct limits , and terminate charging when cells are full and balanced.

Thank you for your reply. I was under the impression you could only balance charge when in parallel? If at all possible, I'd prefer to use these four chargers as I already own them - they can charge at a maximum current of one amp for a single 4.2li-ion cell.

Would it be easier to scrap that and buy a higher current li-on charger that can charge 4 cells together?

 

If you have four chargers, then just connect one charger to each switch as you show.
You could also use two 4PDT switches, or four DPDT relays controlled by one switch.