My "sealant" was NOT holding the battery in, it is just enough to keep the battery from sliding around in the tray. Also both of my zip ties were broken.
What was actually holding my battery in was the van floor- there is a plastic cover on top of the battery and there is not enough room between the tray and floor for the battery to pop out.
I can't say I came up with a better solution however. While my tray is tighter, it's not holding the batteries in and I actually went across the batteries with black zip ties, instead of tying the handles down. I recall intending to return and do something better, but I was mentally and physically exhausted at the time. Need to remember to do that!