Electric wheelchair, mobility scooter
The battery may remain installed if it is securely attached to the mobility device and the battery housing provides protection from damage, the terminals are protected from short circuit, and the battery remains in an upright position when stowed on the aircraft. For complete passenger instructions contact your airline. Advance arrangements and extra check-in time may be necessary. The airline may need to remove the battery and package it separately if the wheelchair cannot be stowed upright in the cargo compartment.
See the regulation: 49 CFR 175.10(a)(16)