Segway PT x2 Reference Manual page 85

Depleting your Segway PT Batteries from the bottom bar to empty
could take several hours, depending on Battery condition and the
amount of charge remaining.
Do not ride your Segway PT to full Battery depletion. To safely
discharge Batteries below the bottom bar, you should leave
your Segway PT powered on in Balance Mode leaning against
a wall in a secure location.
To avoid injury, damage, and to deter theft, be sure your
Segway PT discharges in a safe, secure location, powered on in
Riderless Balance Mode.
4. Fully recharge the Batteries for a minimum of 12 hours, after
which the Battery Charge Level Display will be recalibrated.
NOTE:
WARNING!
CAUTION
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