Envizen ED8890A User Manual - Manual (Page 11)

The usage
this range
Be sure to unplug the adapter when you leave the vehicle.
Adapter
Operating instructions: The internal battery automatically charges when the device is connected to the AC adapter
through a main power outlet. The internal rechargeable battery lasts up to 2.5 hours while fully charged.
Warning: To prevent fire or shock hazard, do not expose the device to water, rain, or moisture.
Never expose battery pack to temperature above 140 °F.
Do not disassemble.
Do not incinerate.