Electric wheelchair, mobility scooter
Lithium metal (non-rechargeable lithium) batteries are forbidden with these devices.
The battery may remain installed only if it is securely attached to the mobility device, the battery housing provides protection from damage, and the terminals are protected from short circuit. In cases when the batteries are adequately protected, it is preferable that they remain installed in the mobility aid; however, there may be situations when that is not possible or safe to do so and in these cases the batteries must be removed. The battery cables may remain connected only if the device is protected from accidental activation. A maximum of one spare battery not exceeding 300 Wh or two spare batteries not exceeding 160 Wh each may be carried. Spare batteries must be carried in the cabin.
For complete passenger instructions contact your airline or the mobility device manufacturer on how to transport your battery as a passenger. Advance arrangements and extra check-in time may be necessary.
See the regulation: 49 CFR 175.10(a)(17)