i've noticed my 6v 'conventional' lead acid battery (5yrs old) is leaking fluid around the top so now I have a small garden of crystals around the battery holder and tarnished marks on the chrome mudguard. i thought this only happens when batteries boil due to overcharging. but the levels are correct and its charging thru a dvr2 and i haven't noticed any unusually high charge rates (should my ammeter be believed). i should note the battery holder had broken so the battery may have been jiggling around, but i'd guess only a bit.
any other reason batteries have acid coming out the top?
thanks