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Old 10-06-2002, 01:14 AM
Phalcon51 Phalcon51 is offline
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Join Date: Jun 2002
Location: Monrovia, CA
Posts: 490
Question about Charging Voltage

As I mentioned in a previous post, My 86 300E stranded me and my family about 70 miles from home last night with a dead battery. I bought a new battery, an alternator and a voltage regulator/brush pack today and headed out to bring the car home. The old brushes were fairly worn down; the inboard one protruded about 5.5 mm, while the outboard on was only about 2.5 mm. Both the running faces appeared relatively clean and smooth. I installed the new regulator/brush set, cleaned the alt. connector and put in the new battery. The resting voltage measured about 12.08v (I don't know how long the battery may have sitting on the shelf and I didn't have time to throw it on the charger). With the engine running at idle, the voltage was 12.24v and at about 2500 rpm the highest charge rate I saw was about 12.44v, and it took probably 30-40 sec. to get there. With the headlights on the voltage at idle was 11.97v and maxed out at 12.15v. All measurements were taken across the battery terminals. This seems really low. Can anyone tell my how to test the alternator in the car with a VOM? Does this sound like a bad alternator as well, or could I have gotten a bum regulator? I've also noticed that the battery light does not come on when I turn on the key before starting the engine. Should it?



Last edited by Phalcon51; 10-06-2002 at 10:48 AM.
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