battery acid on belly

[Cruiser]

1984 M20J 12v.

My battery is a two year old Gill. It has begun to leave a trail of acid from the battery vent tube aft to the tail. I noticed the paint was bubbling in a line aft of the vent when cleaning the belly.

My MSC stripped the paint, primered and repainted this section a couple of months ago (at annual) I have been watching this area closely. I washed it down and rinsed it before the last flight. I got back in the hangar and checked it after a 3 hour flight and the entire area is covered in battery acid again. It even had a build up of white sulfate in some places. Now I see that the paint is bubbled around two rivets as well.

The JPI 700 shows 14.1 or 14.2 volts on the battery for the entire flight. I have the new Mooney solid state voltage regulator. 

Anyone know why this would happen?

 

TomK

[Piloto]

Check the water level on the battery. If above the bottom edge of the cut-out ring it will spill out when charging. Also make sure the top battery box vent opening on the fuselage is facing forward and the bottom one is facing down. Check the battery for shorted cell by measuring the voltage at the battery terminal with master off. If the voltage is below 11 volts it has a shorted cell that will cause overcharge on the other cells, it will still crank the engine.

José

 

[GeorgePerry]

Sounds like it's time for a new battery.  2 years is kinda on the short side for battery life, but if it doubles as a paint stripper a new one is alot cheaper than multiple re-sprays

Most early Mooneys use the Concord RG-35AXC Battery or equivalent.  It's sealed so you don't have to worry about spillage.  Your mileage may vary.

http://www.aircraftspruce.com/pdf/2009Individual/Cat09450.pdf

http://www.aircraftspruce.com/pdf/2009Individual/Cat09450.pdf'>

[carusoam]

I did my battery experiments on an M20C using Gill 35 vs Gill 35 (sealed) - Zeftronics controlled 50A generator

- old style caused repaint of the battery box each year but lasted 3 years.  No matter what white powder protection was used or acid resistant paint that was applied.

- sealed battery worked equally well only lasted 2 years.

Having a mechanic remove the battery box for repaint probably cost more than the battery itself.  This was an annual event.  The 50A Delco generator was strong enough to charge the battery at 14v.  Battery always showed 11.9v while resting. 

Sealed batteries were slightly more expensive than standard.  The rate that battery acid can eat aluminum keeps me in the sealed recombinant technology camp.  Flying more often is probably good for the battery's longevity.

Sorry for putting C data in the J column, but I think it is relevent.

Best regards,

-a-