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New Battery doesnt charge off of new alternator, 77 300D

Hi All, I have a 77 300D where I have been having a problem where the battery is not getting charged from the alternator. I replaced the alternator and the battery still does not recieve a charge (I test using my multimeter). The battery is brand new and fully charged. I replaced the alternator as I should have, making sure the battery is disconnected when plugging the altnernator plug into the alternator and yet my battery is still getting drained.

I have tested the continuity from the battery to the alternator plug. I hooked my battery up while having the alternator unplugged. I put my multimeter in the terminals of the alternator plug and had a battery charger on my car battery and was able to get voltages from 12.2 all the way up to 13.8.

Upon reading the schematic I see that the positive lead from the alternator goes to the starter and then to the battery. Could there be a problem with my starter that is preventing the battery from getting a full charge? The starter does operate perfectly though.

Thanks for any help anyone can give!

-James

Reply to
james.freire
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Did you replace the voltage regulator when you replaced the alternator or did you use the old one?

Reply to
Richard Sexton

The electrical diagram for my car says that it has an internal voltage regulator and the alternator i purchased, a bosch AL80X also states that it has an internal regulator.

Reply to
james.freire

When you say "new alternator", do you mean factory fresh, never been in a car before, or do you mean rebuilt? My experience with rebuilt alternators has been pretty dismal, rebuild seems to mean "Replace the brushes, slap on a new coat of paint, and ship it back out." Last alternator I replaced I went through 3-4 of them, till the auto supply place got sick of my saying "Nope, try again" and allowed me to use their tester to find a good one.

[Same thing with rebuilt starters, but that's another story.]
Reply to
William P.N. Smith

Internal is an odd choice of words for the thing that bolts on the back, I'd have called it "integrated" but no matter...

You're leaking electrons someplace and you have to find the leak. Get a volt meter and see if they're at te alternator, then follow the wires and see where they're leaking out. Could be a ground issue too, if you haven't taken off your ground connections, cleaned them to within an inch of their life (must be shiney) and put them back tighty with conductive grease in recent memory then you should probably do this too.

Reply to
Richard Sexton

Since the alternator is putting out proper voltage your problem is a drain somewhere else. Disconnect the ground cable and put a multi-meter between the ground post and the ground strap. You shouldn't get any current flow if everything is off. Make sure you don't have a hood light that comes on when the hood is raised. I've known of glove box lights and trunk lights that have drained batteries causing a lot of headaches. This is simply a matter of isolating the drain. Also, some radios cause a small drain all of the time as well. This shouldn't be a cause for concern with a new battery but start checking everything. Good luck!

Reply to
Ernie Sparks

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