Battery Boxes & Trays

Sizing a battery box or tray

Buy for the battery you actually have, not the one that came out of the rig. A box a size too small will not close, and one that is too big lets the battery slide around, which is the exact thing the box is meant to stop.

A few things decide the fit:

• Group size. Boxes and trays are cut for a specific case, and Group 24, 27, and 31 are the common RV house sizes. Measure your battery's length, width, and height before ordering, because a Group 31 will not drop into a Group 24 box.
• Vented vs. sealed. Flooded lead-acid batteries need a vented box with a hose routed outside, since charging releases hydrogen. Sealed AGM and lithium batteries do not off-gas in normal use, so an enclosed box or a simple tray works.
• Hold-down hardware. A tray with a strap or J-bolt frame keeps the battery from shifting and shorting against nearby metal. This is the part people skip and regret after the first washboard road.
• Material. Marine-grade polypropylene shrugs off acid and UV. A cheap case that goes brittle in a couple of seasons tends to crack right when you are wrestling a heavy battery into it.

Match the box to your house batteries first, then plan how you will cut power to them. A disconnect switch mounts cleanly near the box, and proper fuses and breakers protect the cables running off the terminals.