Battery Keeps Going Dry????

[i-osprey]

I have a 1981 300D and I put a (high) maintenance battery on it about a year ago. It is the proper battery for the car and has given me no trouble until the last two weeks.

About two weeks ago in the course of a day it stopped holding a charge. After two boosts I took off the covers and it was BONE dry.

I got some distilled water and filled it up and it held a charge beautifully for about two weeks. It started the same thing today. I take off the caps and sure enough it is dry again.

My question is what would cause my battery to go dry?

I will say that I beat on the post a bit the day it first stopped holding a charge when I was tightening the clamp and I have put the post under a bit of strain in the past when trying to get a ground wire on it.

Besides a crack in the battery itself, how could the water be gone that fast?

Could my alternator be "boiling" off the water?

I'm stumped.

It looks like the water has come out from the caps based upon the debris around the area that apparently stuck to it when it was wet. Also, there is a hole eaten through the battery tray and into the fender well.

I suspect that this has been there a while but I don't know for sure.