Here's how I fixed the water in my battery compartment. I purchased a diamond-plate pickup truck, box edge mount tool box. Its the only one I could find that would fit between the front of the TT and LP tanks. Most tool boxes are 20" deep...too big. Since it locks, I know my battery will not walk away:
The battery, in the box fits neatly and tightly inside. I installed a West Marine fuse block to separate circuits that previously all ran to a common connection at the battery. I plan to attach the fuse panel to the battery box yet:
At the battery, I eliminated the totally garbage factory connections that used wired nuts and fabricated a terminal block for the positive terminal. I did this mod when the TT was brand new and the connections were already corroded and rusty from the wire nuts. Wire nuts are NOT designed for outdoor use unless these are used:
Waterproof Wire Nuts 8-22 Ga (20-Pk)
Obviously they cost more so Jayco doesn't use them.
The orange 12V+ cables are something I purchased at a local car stereo install shop. I believe its 10ga and used for high power car amplifiers. The terminals are designed for home electrical breaker boxes. You'll notice I have two spares. All fasteners are stainless steel. Everything is soldered and has heat shrink tuning to protect the connectors. Just below the orange cables, you can see where the hot wires exit the box, through a grommeted hole. A bonus is all connections come off the (+) terminal with one nut.
When the TT is in the driveway or campground, the WD hitch bars and anti sway store in it. During travel, the longer leveling boards stow there, keeping dirt, sand and insects out of the TT. It has worked out very nicely.
Hopefully this helps give someone ideas on how to spend more money. At the very least, unscrew the wire nuts on your trailer and check the integrity of your connection(s). My guess in may cases is, they're not good.