Interesting... this battery is no larger than mine... you can increase the tension on the belt from the front bearing hub... when torque is applies through the belt...
it raises slightly off the batt...
if you look closely at the photo below, you will see the battery does not fit parallel to the upper deck... There just not enough space between the bulkheads...
If you wish to fit across the chassis, you will have shim the batt straps 3mm...