Originally posted by JCE
BTW, that clear plastic tube vent line is for any hydrogen gas given off by the battery. Hydrogen gas can apparently be given off by an overcharging battery or one that gets too hot.
I'll vouch for that!!!
I don't have a vent line on the W124, but about a year ago, a failed voltage regulator caused my alternator to overcharge (measured 17.5 volts at the terminals!!), and I could see (and smell) the vapors being emitted from the battery!!! Pretty noxious too!