I have tried to replace the coach battery but could never get it out of the engine compartment. The battery is about .5" to big.
I found a different manual for the Axis on line under owner resources at
http://thormotorcoach.com/owner-resources
On page 99 it tell how to get the battery out.
The chassis battery is accessed through the passenger side dash on the Axis and
Vegas units.
1. Remove the passenger side work station.
2. Remove the seal and wood access.
3. The battery will be below and forward of the opening.
4. Reinstall the wood access panel.
5. Reseal the panel. Failure to properly reseal the panel will allow air intrusion into
the cab of the motorhome.
6. Reinstall the passenger side work station.
I have not tried this but it does let you know how Thor thinks you get at the battery. The manual I got when I bought the unit did not have this section in there.
Best of luck getting it out.