18650 3S 10A Lithium Battery Charger Protection Board Module for 3pcs 18650 Li ion Battery Cell Charging BMS 3.7V 11.1V 12.6V|protection board|18650 protection boardbattery protection board - AliExpress
two Li-ion 3.7V series charger from USB | Forum for Electronics
Figure 1 from Charging Li-ion Batteries for Maximum Run Times An understanding of battery-charging fundamentals and system requirements enable designers to choose a suitable linear or switch-mode charging topology and optimize battery
Lithium Ion Battery Charger Allows Choice of Termination Method and Includes 100mA Adjustable Low Dropout Regulator | 亚德诺半导体