[Resolved] Alternator not charging battery - 1972 Beetle

[sjbartnik]

[Danwvw]

B+(Big red-white wire) should have battery on it all the time. (if not look under the back seat it's supposed to hook up to the battery, just get a battery cable that has a place for it. Some people hook them up to the starter which is fine.
The green wire for the field at the alternator will have just a little voltage on it with the key on provided it's going to the Alt/Gen light, But when your start the engine and the alternator start's charging it should go to 14 volts DC. And B+ goes from 12.6 volts to 14 volts.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[ErikTande]

I think that was it. I assume I should have been seeing at least 12v at the generator, so I followed the power wire and found a split, I think one goes to the starter and the other to the alternator, and one of these red ones was unplugged. I plugged it back in and now the alternator light goes out when the car is running. It will blink on if I turn the lights on, then fade off again. So I assume that means the alternator is working, at least somewhat.


I'm still only measuring 12.6v at the battery now though during idle.

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http://www.youtube.com/velocitylabs

[sjbartnik]

[JKLundy]

I found out the hard way that having a powder coated alternator stand can also keep it from charging. The Bosch alternator frame to b+ terminal was 14.6v but to anything else on my engine or even battery (-) was 12.4v (battery voltage). I sanded powder coating off of my alternator stand and put the strap on with some copper tape in the gap. Tightened it up and all is well Try checking voltage from b+ terminal to alternator housing, should be 14.something or thereabouts. If not alternator is likely bad, if 14.? You have a wiring issue.

[rockerarm]

Hello.
You should have the same voltage reading at the battery positive post as well as that B+ post on the alternator. That smoked brown wire has already been addressed. And finally, the small "exciter wire" should link the warning lite on the speedo to that push-on terminal atop the alt.
If you have battery voltage at the alternator B+, then use a test lite of some sort for the "exciter wire", commonly referred to as terminal 61. Hook up your homemade terminal 61 circuit. It can hook up to the coil +, or even to the battery positive. Hook other end to the push-on and you now have a basic alternator warning lite that will also "excite" that circuit. Start the car up, lite should go out, and read your voltage at the alt's B+. This is the simplest way to diagnose your alt. If you have voltage above battery 12.5v, your on your way. If not, poss the alt is the culprit. You may want to fab your own alternator wiring harness.
Hope this helps, Bill.

[Zero Cool]

Hi. Sorry this isn't exactly related to the post but in the picture Erik posted there is a little plastic yellow cap on a tube coming out of the carb. I just bought a bug with dual carbs and one of them has that same cap and the other one doesn't have it. My carb floods and gas comes out of that tube. What's that cap called? Any idea where I can buy one?
Thanks

[ErikTande]