Dead Battery or a bad regulator?

[Bijan]

This morning after I arrived at my destination and parked I found a much closer parking spot so I decided to go back and bring the car closer. The car did not start. So here is the question the battery is 56 months old so I am suspecting the battery but how can I check to make sure it is not the regulator. Of course I am not sure if a 94 325ic has a regulator or the job is done by the computer. In any case I appreciate any input .

[Dave at Pelican Parts]

Try recharging the battery. If you don't have access to a charger, try a jump-start.

Once the engine is running, use a voltmeter to measure across the battery posts (not the clampso on the posts, the posts themselves). If you don't see 13V or more (probably more like 14V at a couple of thousand RPM) then your charging system is not working correctly. If you see over 15V, you are over-charging and you have probably puked acid out of the battery. Clean it up with baking soda and water, and replace the voltage regulator.

The VR is probably inside the alternator (it is in most modern cars) so replacing the VR and replacing the alternator are pretty much the same thing.

--DD

[Bijan]

The voltage across the battery was 14.2 volts but I noticed that there was no water inside the battery (bone dry) so I filled it up with water and let the car run for about 30 minutes but at the end when I turned the car off it wouldn't start again. Does that mean the battery can't no longer hold the charge or am I doing something wrong.

[Dave at Pelican Parts]

It's possible that the battery is completely dead, though I have had luck refilling them, letting them sit overnight, then re-charging.

Probably simpler to buy a new battery, though.

--DD