batteries - Why does this mobile phone battery have 4 terminals? - Electrical Engineering Stack Exchange
Pin functions of 2, 3 and 4 terminal mobile batteries
A Designer's Guide to Lithium Ion (Li-ion) Battery Charging | DigiKey
Laptop Battery Secrets
LTC4054 Single-cell Lithium-ion Battery: Circuits, Pinout, and Datasheet [Video]
File:Contacts on DeWalt 20V Max battery.jpg - Wikimedia Commons
Adafruit Universal USB / DC / Solar Lithium Ion/Polymer charger [bq24074] : ID 4755 : $14.95 : Adafruit Industries, Unique & fun DIY electronics and kits