Keep The Top Of Flooded Batteries Bone Dry

Rain water is not nearly as conductive as condensed acid. I was referring to the top of the (hold your breath)..........jar

not the plates which of course needed not any elaboration.

To STOP dead in it's tracks, forever, acid attacking steel hold down parts, clean the parts with baking soda solution then apply a heavy (coats) of asphaltic based undercoating which comes in a spray can at your auto parts store. If the can says you can paint it, it's not asphalt based.

I did this on the Miss Kelly II, thirty two years ago and last I checked the battery compartment had gone through a dozen sets of batteries but not a fleck of corrosion on the steel.

The circular joint around the battery post as it passes upward through the lid MUST BE SEALED or GASKETED. Oil impregnated felt washers are the usual answer to this but they work best if they are saturated to the point of dripping wet.

Th holes on top of that made in Xaopeng battery box are there are an aid to injection molding. Useless and actually detrimental.

Pry up the flapper tops on your RV battery and look down into the trough to see the six cell filler holes. Is the space BETWEEN the holes wet? That's a voltage leakage path. Dry thoroughly. Smear silicone grease between the holes, clean and dry the flapper top plugs and smear grease around the plugs. This will REDUCE self discharging.

MEXICOWANDERER wrote:
Cell to cell electrical leakage can and does develop if the top of the battery gets wet. This is an issue with flat top recessed cap batteries. The leakage can grow and become dozens of milliamps. It is especially wonderful if leakage is cell to cell causing the state of charge balance to become unequal.

Smear dialectric silicone grease on filler cap plugs to seal. The built in cap vent acts like a minor league recombinant chamber.

And remember MOST of the unexplainable corrosion of battery terminals comes from the imperfect seal between the battery lid and lead battery post. The temperature expansion rates are wildly different and the culprit is GAS not liquid electrolyte.

When I bought this MH 10 years ago I was worried of my Magnatech converter "boiling my batteries dry so I was always overfilling the cells causing the wet top as you describe and a lot of corrosion. This coupled with heavy inverter and alternator usage caused a lot of corrosion at the terminals and angle iron to hold the batteries in place. The corrosion was green and a wet build up. The corrosion actually ate some of the terminals away. I now fill the cells to about a 1/2 in from the top, run my refer on propane and clean the tops of the batteries when I fill with water. This has greatly reduced corrosion. However I still get corrosion on my angle iron to hold down the batteries.

Francesca Knowles wrote:
A very timely tip for me- just replaced the tongue-mounted battery box on the little trailer with one we've had on the shelf for years. It's a "marine" box and I noticed that it has vents cut in the top-? They're the two ovals that show in the pic below.

The box isn't airtight or otherwise sealed- my inclination was immediately to plug those holes to keep the rain out. Should I do that?

Thanks!

Yes. I have the same type of boxes (6 of them). I used pieces of "generic" Eternabond over the holes. There is plenty of air gap between the box and lid for venting. Especially when they are on the tongue and the trailer is moving.

jolooote wrote:
Do U mean the plastic top of the housing or are U saying to let the top of the plates be dry???

Plates need to be submerged at all times.
Top of the battery case needs to be dry. More an issue for exposed equipment such as the tongue of a travel trailer.

Do U mean the plastic top of the housing or are U saying to let the top of the plates be dry???

FK, I use similar ones but got the Snap-Top type from Wang Mart. I HATE THOSE STRAPS! On my old trailer I eventually threw the straps away and just used bungee cords to hold the lid down. Did I mention I HATE THOSE STRAPS!!

A very timely tip for me- just replaced the tongue-mounted battery box on the little trailer with one we've had on the shelf for years. It's a "marine" box and I noticed that it has vents cut in the top-? They're the two ovals that show in the pic below.

The box isn't airtight or otherwise sealed- my inclination was immediately to plug those holes to keep the rain out. Should I do that?

Thanks!

I always put dielectric grease over the terminals to prevent corrosion. Never have any problems.

Thanks for the tip Mex.