Camco 55370 Vented Double Battery Box, Group 24

If you're running a house bank on a boat or an RV, two Group 24 batteries add up to a lot of weight sliding around loose. The Camco 55370 puts both of them side-by-side in one sealed enclosure, and it keeps them from shifting when the water gets rough or the road gets bumpy. It's the kind of part nobody thinks about until a battery tips over in a locker. Then you think about it a lot.

Here's the part that matters most. This box is vented. Flooded lead-acid batteries give off hydrogen when they charge, and hydrogen in an enclosed space is exactly the problem you don't want in a bilge or a battery compartment. The 55370 has a sealed lid and an external vent port, and it ships with the hose, hose mount plate, two hose clamps, and a louvered vent grill so you can run that gas overboard the right way. That's why it meets US Coast Guard CFR 183.420 and ABYC E-10.7. If a surveyor or an insurance inspector looks at your install, a compliant vented box is one less thing to argue about.

One thing worth saying plainly. Don't cap the vent port and call it done. We've seen people install the box, skip the hose run, and plug the port to keep water out. With flooded batteries that traps the hydrogen you were trying to get rid of. Run the hose to the louvered grill, terminate it overboard, and let the box do its job.

Camco doesn't make you source the small stuff separately. Open it up and you get two battery terminals, the vent hose and its mount plate, two hose clamps, the louvered grill, foam tape, putty tape, and the mounting hardware. The foam and putty tape seal the vent penetration and the lid so you're not chasing fumes or water later. It's a complete kit, which means one trip to the boat instead of three trips to the parts store.

Size-wise, the box is 17-5/8 inches tall and 15-1/2 inches wide. Depth is 13-7/8 inches with the vent ports fitted, or 11-7/8 inches if you run it without them. Measure your compartment before you commit. That 15-1/2 inch width fits snug in a lot of mid-size express cruisers and travel-trailer battery bays, but it doesn't leave much room on either side for a battery switch or a bus bar, so plan your layout first. And leave yourself an inch or two of clearance above the lid. You'll need it to pull the lid for maintenance without unbolting the whole box.

The shell is black polypropylene. It shrugs off battery acid, fuel, and salt spray, which is the whole reason you don't want a bare battery sitting in a fiberglass locker. One tip from guys who've installed a few of these: if the box lives somewhere it takes foot traffic or direct sun, back up the mounting holes with fender washers and a backer plate on the stringer. Polypropylene is tough, but it's still plastic, and a lid that gets stepped on season after season appreciates the support.

Works with flooded Group 24 batteries, and it works just as well with AGM. If you've moved to AGM or another sealed chemistry, you may not need to run the vent at all, since sealed batteries don't off-gas under normal charging. Either way, you've got a secure, acid-resistant home for two batteries that stays put when the boat pounds or the trailer bounces. It's a solid choice for a mid-size boat house bank, a dual-battery RV setup, or any dual-battery install where you want it done to code and done once. Buy the right box the first time and you won't think about it again for years.