spree17, the voltage readings for both cars seem fine to me. You're good to go in my opinion.

Ditto, you should be good to go.

I cant thank you guys enough. I used to be pretty mechanically inclined but it has been a lot of years so my "skills" are rusty. If not for the boards search feature and all your advice and wisdom I would have been lost and just changed the alternator out probably. :)

If your battery needs the water checked you should replace it with a maintenance free battery.... :)

Sounds like you are good to go on the alternator though, that is proper voltage output.

Thanks Paw. I'm a bit nervous to drive it far now though because I dont want it to die on me again. All I did was add water to what seemed like a bone dry battery and cleaned the voltage regulator. Do you think that could have fixed the problem? The readings have been strong every time I tested it today.

Car does not seem to be fixed. Battery was at 12 this morning with 13.80 when started. Then I drove it and came home. I took new readings. Some under load of lights or a small tire compressor connected to the cig lighter. Some not with anything on. The readings were all over the place while running. It would fluctuate between the 11's and the 13's. I could hear the engine pick up and decline with the readings. I know you guys are probably sick of my questions but how can I tell if it is the battery, the regulator or the alternator that needs replacing? Please advise me!!!! :)

Some Auto parts stores offer free battery and charging system diagnostics.

Call around, ask and get quotes. See my previous post on the subject in this thread.

If electrical consumers (ie: AC compressor) are cycling the voltage readings will fluctuate....is the AC on?
Acky

I turned some on at times and also left them off. When it goes in to the 11's I'm concerned. I hear the engine decline and see the headlights go dimmer. I think the battery is OK. When not running its almost always 12 plus volts. Ive narrowed this down to the regulator or alternator.

OE regulator P/N 002-154-72-06. About $60.

I changed the regulator. So if this doesn't work it probably would be the alternator. My car has around 175,000 miles

Reading before starting was 12.00
Reading after starting got around 13:80
Drove the car around the block
Came home and turned on the high beams, the radio and the windsheild wipers. Reading fluctuated from around 13:10-13:20 with everything on parked in idle.
Turned car off. Battery read 12:40

What do you guys think? Do you think the new regulator fixed the problem?

Give it a rest. Check tomorrow, and you'll probably know for sure. I'm guessing that you're going to be OK, but at 175K miles, the alternator is probably due, too.

OK Cal thanks for the advice. I dont mind paying for an alternator ($107 from autozone after core refund) but it seems like a big job for me to do myself. UGH, lol :)

A "solid and strong" battery should be around 12.5 to 12.6 volts with the car off for even a few days.....a battery with a bad cell will fall to the 12ish or below range. If it does, replace it. I had one do that when it was only a year old. I decided to go with the extra-good MB battery from the dealer. 2+ years later and 0 issues.

Thanks for the advice. The battery was 12.24 this morning. I never fully charged it. I just jump started it and drove it around the block. If I need to get a new battery I should get around 50% off since this is a prorated 6 year battery. I may drive to a autozone and ask them to test everything. Hopefully the car will not die on the way there. I did refill the battery with water this week and change the regulator.

I have 1990 190E with the same problem, and had the car towed home.
After I charge the battery, my altenator provides 13 volts and with the higher RPM and lights on 25 AMPs.
Should I change my Atenator? There must be the same problem??