This is what the owners manual says.
Replacing battery
1. Lift seat and push forward.
2. Using two 1/2" wrenches disconnect BLACK
battery cable then RED battery cable.
3. Position deck to lowest setting.
4. Front underside of frame, remove the nuts
securing the battery hold-down.
5. Carefully remove the battery from the mower.
6. Install new battery with cable terminals routed
to the center of the battery