Originally Posted by Donkey Hotey
If what you described were even remotely true, rubber and woven hold-down straps would have to be magic.
The battery is in a pocket. There is a friction component keeping the battery located within that pocket. The ONLY thing the bolts have to do is keep downward pressure on the battery and it ain't going anywhere--same as straps.
Rocking the battery exerts a lifting force and only the tiniest of bending forces. Those bending loads are negligible until long after the battery has translated enough to leave the tray. It's not going anywhere.
My biggest worry in that installation would be engine vibration being transmitted directly into the dangling lead plates in the battery. That's a sure-fire way to destroy a battery.
Draw a simple force diagram of the design we are talking about. ANY side loading on those threads is a problem.