My Concorde CB-35A battery has vented battery acid out the top, corroded
the case and plugged the drainhole and generally made a mess.  It was
purchased 1 year, 4 months old.  It is/was working fine.  Fluid was down
about ½ inch and still covering all the plates.  

What causes this?  Should I refill the cells and continue to use?
Or buy a new RG battery? Or perhaps the Panasonic CL-LA1233P (33 amp
hour) sealed lead acid advocated in previous posts. (I have a single
battery setup.)

Is there anyway to remove the ugly brown/black stain on the insulating
blanket where the battery acid ran down the firewall?

Carl Cadwell
N25CL  IVP

P.S.  Great Redmond Lancair Fly In this weekend.  Weather was terrific.
So many gorgeous planes- 40-50 must have shown up.  Our thanks to the
Lance and Lancair family for being great hosts and a fun time.