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!