So, I have two 2000 mAh LiPo batteries that are going to be powering a GSM modem (on an arduino shield) a GPS and a motor. I considered just boosting to the motor (needs 6V), and using the batteries in parallel, but decided that it would make more sense to hook the batteries up in series and use LDOs to get down to the 5V needed for the shield and 6V needed for the motor.
The problem then arises: how do I charge the LiPo batteries back up, using only my external microcontroller and the charge controller that came with the first battery? The charge controller can charge at up to 500mA.
My gut instinct was to create a MOSFET controlled circuit to switch the batteries to a parallel configuration, and to then connect the charge controller to the batteries.
4 MOSFETS feels like overkill though. Does anyone have any better ideas?