flowdrip

I have a 1991 190E that is driving me nuts. I replaced the battery 2 weeks ago because the old one was 7 years old and started showing it's age. Bought a new 84 month battery from Kragens, installed it and the battery was dead in 5 days. So I figured that the alternator was shot, brought the battery back to be charged and to also have them test the alternator. The alternator was fine, it was the battery that was no good. I get another battery, same make and model, and this thing also lasts for about a week and it dies. I take the alternator out again and bring it to a different parts store to have it checked, and again it passes with flying colors. They test battery #2 and it is no good. I get battery #3 yesterday, installed it, fired up the car with no lights on, radio, A/C, fans..... nothing but the ignition. The battery light immediately started glowing red, (kind of faintly) but would go off if I stepped on the gas and revved the engine a bit. Now doesn't that show that the alternator is working properly and the belt has correct tension at the alternator?

The guys at Kragens are saying there is something else wrong with my car, and it is draining their batteries. I had a helluva time getting them to give me the 3rd battery even though there is a 1 year replacement warranty on it. Can anyone give me any insights on what I should look for to solve this problem? This car never had an electrical problem in the 4+ years I've had it, it just started when I swapped batteries. Makes me want to go.....

nasscmw

I had a similar problem but that was due to the wiring problem. something was sucking up the juice of my car after an engine transplant was done. Maybe something happened along the way while changing the battery? I don't know because if the alternator's okay and the battery's supposed to be okay, something else is sucking up the juice then. A wiring issue perhaps?

C43AMG

Check the voltage regulator

flowdrip

Wouldn't a faulty voltage regulator show up when the alternator was being tested? I assumed it would, but after further reading, it does sound like the voltage regulator is the culprit. Thanks for the answers, guys!

flowdrip

Good call, C43AMG! The voltage regulator was replaced this morning and I no longer have any electrical malfunctions. You made my day!

C43AMG