I'm looking for a good and space-saving solution to charge two 18650 batteries in series.
The project is a small boombox, using an amplifier board that works with voltages between 4.5V to 25V. The battery will be fixed inside and might be rechargeable from a 5V wall charger. I already have a few projects working with one battery and the TP4056, but I've been reading that this will not work for series charging.
Does anyone have a solution?
Be lenient, this is my first post. Thanks in advance.