TEC4056 18650 Battery Charging Circuit. It is an ideal circuit for charging 18650 batteries. Battery charging with 0.3, 0.5 and 0.8 ampere current options By default, the charging current is 0.8 amps. You can change the charging current by removing the resistors on it. The LED on it turns red when the battery is charging, and green when the battery is fully charged. It works with Micro USB.