i have had the same problem but when i put the batteries in they fit perfect in the bottom actually locking them in place and cured the tipping problem i just cut a plywood board to cover them wired them up and don't have to mess with them anymore they stay inside even while charging the batteries i used are 2 (ub12120) jell cell batteries a little more expensive but will last me all day with my electrics charging and anything i throw at it and on the flight line all i take is my starter and my glow plug driver so loosing the space in the bottom doesn't hurt and that gives me more space above i did wire the box up to be able to run all my stuff off of like starter and charger just by plugging in where i charge it