So for a portable project, I will be using two lithium ion 2200mah 3.7v batteries in series to give me 7.4v. I have a USB powered 3.7v Lithium Ion charger found here https://www.adafruit.com/products/1905 . How could I charge both the batteries in parallel and then use them in series for 7.4v?
All help is greatly appreciated.