At your next battery change, I strongly suggest replacing the four screws holding the bottom of the battery box with stainless screws, sealed to the box or covered with silicone sealer if your bird is fitted with mild steel screws.

My 1976 112TC screws were not resistant to acid and disappeared after an early battery failure -- 13 months at 40 hr. -- I didn't fly for 30 days, unaware of  the shorted out battery cell and acid leak.  This resulted in the acid dissolving most of all four bolt heads.  I'm sure some of the acid had been dispensed out the bottom vent as the paint had some blisters, but some had also seeped through the missing bolt screw holes causing a large accumulation (1/2 cup) of white aluminum oxide residue. 

All is now repaired, but with SS screws.  While disassembled the master solenoid with 3000 hr. use was replaced as a preventive measure.

Ol' Roy
MI (08C)& FL (APF)
N4572W (112TC)