My electrical system has an Odyssey battery which is used as an aux battery to power an E-Buss. It is positioned inside the cockpit just aft of the FW on the tunnel cover. I fabricated it to allow my throttle cable to pass just to the right of the box to connect to the IO-180. It is held to the tunnel with four AN3-4A bolts through the tunnel angles. Its a tight fit but allows the tunnel cover to remain unchanged except for a rectangular hole to the left of the box which has a handle to actuate a parking brake valve. The wires running down the right side under the tunnel cover are protected from the bat box bolts with a strip of HPDE plastic between the nutplates and the conduits. The difficult part is getting everything spaced and protected under the cover.
Aux Batt Box bolts to the tunnel angles just behind the FW.
