Typical full charge time is 60 minutes when charged with an A/C adapter. The charger uses a micro USB interface. A standard USB to micro USB cable is used to connect the charger to the power source. The power source can be a USB power source, such as a computer. A/C home power adapters will also work.
See the SRAM RED eTap System Overview video for a tutorial on removal, installation, charging of the batteries, and the indicator LEDs.