It takes approximately one hour to charge a SRAM AXS battery 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.