Water on Battery - Solution?

[Andre]

When I wash my plane (CTSW), water leaks between the fuselage and cowling and pool around the negative terminal of my battery.  I am assuming that the same would occur if the plane was parked outside in the rain.  Am I the only one with that problem?

I found this out the hard way.  I did my annual in November after the plane had been stored for a while.  Once done, I washed the plane to get rid of the accumulated dust and went to take my test flight.   Taxiing was no problem.  So I took off and after turning crosswind and retracting the flaps, I took a look at my voltmeter and actually saw it going down.  At that point, I had about 8V left so I quickly called the tower to tell them that I was losing my electrical and was requesting an immediate landing.  I pulled all the non-essential breakers i.e. everything except for the radio.   By the time I was downwind, the tower could not hear me and I was down to 6V.   I landed without incident with -6 flaps looking for the tower light signals for the first time in my life.

After taxiing back to the hangar, I removed the cowl and found the water pooling around the negative pole of the battery.  The seam between the cowl and the fuselage is right above the battery.   My guess is that after I took off, the water migrated to the positive pole and shorted out the battery.  I do not know if this would have happened while flying in rain but I am glad that I did not have to find out.

The reason I never figured out that before is that I usually wash the plane about once every three months (so 3 times so far since I have owned it) after a flight and then put the plane away.  This was the first time I flew it after washing it without the plane sitting for a  day or so before I flew it - enough time for the water to evaporate I guess.

Now for the possible solutions that I can thing of:

Current solution:  Adding a gasket between the cowl and fuselage.  I did that by gluing a rubber gasket (part of an old bicycle tube) to the fuselage but that did not make much a difference.  Less water is pooling but any water is too much so...  The gasket is clearly not thick enough.  

Easy solution:  Tape the seam between the fuselage and the cowl.  Annoying to do every time I remove the cowl which is about once a week.

Hard solution.  Build a new battery box so the the poles are facing sideways and forward as oppose to up so that water cannot pool.   The box should have an a full cover on top with an overhang to make sure that the battery cannot get wet.  That requires changing battery cables with longer ones.  

If somebody else had this problem, how did you handle it and how did that work out for you?

Andre

[Anticept]

Put a very thin piece of soft foam on the mounting flange for the cowling along the windshield area. Rubber won't conform very well.

[FastEddieB]

No doubt it’s a good idea to keep your battery dry, and you should track down where the water is getting in. Others more familiar with the CT will no doubt chime in with remedies.

That said, water is not all that great a conductor, especially at 12v to 14v. Wet batteries normally perform just fine*.

Just keeping water off direct contact with the terminals should be enough. Vaseline, grease or Corrosion-X on the terminals can do that. Auto parts stores sell battery terminal protector spray, and I like having a can of that around.

Next step up would be something like PlastiDip either sprayed or brushed on the terminals.
 

 

*One exception is likely Lithium-Iron batteries that have internal circuitry and might not be watertight.