Taylor-Dunn TT-316-36 Operation, T Roubleshooting And Replacement Parts Manual page 133

Industrial Charger Troubleshooting
The charger supplied with this vehicle is either specified or provided
by the end user.
Refer to the documentation supplied with the charger or contact the
charger manufacturer for more information.
Turn the Key switch OFF BEFORE disconnecting the batteries. Disconnecting
the batteries with the key switch ON may corrupt the controller
programming resulting in a fault code 1 (refer to fault table).