Weather Stripping the Battery Box

[Aktundra]

Not sure if this question is better posted in the electrical forum. I am restoring a 1963 Bambi. About done closing leaks in the exterior skin. but noticed the floor was damp due to leaks from the battery box. I have read several cautions that the battery box should not be sealed due the potential of gases put off by the battery.

As I recall, this area was one of the most rotten areas in the floor. I thought it was due to potentially corrosive leaks from the batteries over time. But I'll bet a good part was also due to exterior water leaks. Attached are some pics of a battery box opening from a sister Airstream of similar vintage.

I could caulk around the base of the box, and weather strip the inside edges of the opening, but not sure if this would be wise. What would be safe and appropriate to keep the water out, yet properly ventilate this area ?

[markdoane]

As long as you keep the two holes in the door open it would be OK. You need one vent high and one vent low.

[Silver Hawk]

You might consider eliminating the whole problem by sealing up the outside door permenately and going to AGM batteries that don't need outside venting.
Advantages: 1) no leaks, 2) they last longer, 3) zero maintenance.
Disadvantages: 1) cost more (made up by longer life).

[Protagonist]

Originally Posted by markdoane

As long as you keep the two holes in the door open it would be OK. You need one vent high and one vent low.

Actually, one hole high in the door is all you need, and one hole in the floor that serves as both an inlet for air and an outlet for water. And elevate the battery slightly (about the height of a Lego block) so that water isn't trapped by the battery.

Also, shape the vent hole so that water is deflected away from the hole instead of dripping in. Easily accomplished by inserting a wooden dowel into the vent hole that is about the same diameter as the vent hole, then pressing down gently. This will slightly bend the top edge of the vent hole outwards, and the bottom edge of the vent hole inwards. This will help prevent water dripping down the door from getting in, though it won't provide perfect protection against wind-blown rain.

By the way, even battery boxes for AGM batteries are required to be vented. AGMs don't spill, but they can outgas. They don't outgas as much as a wet-cell, but they do outgas. Which is why you can use an AGM in any position except upside down (if upside down, lighter-than-air hydrogen gas can't escape).