From their webpage:
"Segway® Human Transporter Device
Batteries on the Segway® Human Transporter are lithium, similar to a laptop battery, and do not require removal or any disconnection of the power source. If this device is used as a mobility device, it may be stowed in the cabin on a first-come basis. Customers may ride their Segway to the aircraft door and guide it into the closet. It can climb stairs."
https://www.aa.com/i18n/agency/Trave...orter%20Device