J bolt with jamnuts.
A battery is a big heavy thing, so why do I need to bolt it down? Well if you've ever been in even a Minor collision you know how things can get knocked around. I could tell you about the time the battery shook off it's tray on a rough road, fell over jamming the throttle wide open, then started a fire! 'Nuff said; J-bolts (2 needed) with nuts are MM224, hold-down bar is 34G2065.