Crazy Electric Issue/Alternator

[Michaellatini]

Driving the alternator light came on and stays on. Prior to that when turning on the turn signal the alternator light would flash a little red.

Alternator has 1500 miles on it and is a year and a half old. It's wired like the picture below, I have electronic ignition and fuel injection.

Checked all wiring at battery, alternator and dash. All connections are good. Light on dash comes on with the key off and connecting to ground.
Checked battery voltage at idle and 1500rpm, 11.7 and dropping
Connected battery charger set to 2A charge and instantly tripped the batt chg circuit breaker.
Used an Ohm meter to checked the + battery terminal to a random ground point thinking maybe it's a cut wire somewhere but, no. Infinity on the ohm meter.

What could be causing the battery charger to trip instantly? Voltage regulator melted?

Thank you in advance for your input.

M

[cbeck]

What happens when the battery is disconnected from the car, and then hook charger to the battery?
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My cut in half and rebuild thread
www.thesamba.com/vw/forum/viewtopic.php?t=647779

[Michaellatini]

The battery starts charging and stays charging.

[VW_Jimbo]

Is that the ignition switch with the "15", "30" and "50" circuit numbers in that circle?

And what is the big red dot in the D+ feeder? It looks like there is a bulb, too?

Something don't look right on that D+ circuit.
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Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[Michaellatini]

Yes, that’s the ignition switch. The large red button is the alternator light added to the dash and the bulb is to trigger the alternator to start charging. I got this schematic from somebody on the samba. He said it’s the way it Hass to be to work with the fuel injection computer.

The car ran fine like this for 1500 miles.

[VW_Jimbo]

[busdaddy]

[Michaellatini]

Thank you Jimbo. Have a good evening.

[Michaellatini]

The tripping of the circuit breaker on the charger was operator error! Nicked the battery hold down. Still not charging.

Must be a bad alternator. Paid $189 for it.

[VW_Jimbo]

[Michaellatini]

Volt meter at the battery when running.

[VW_Jimbo]

[Michaellatini]

Voltage drops running. Key on voltage is whatever the battery is at. Idiot light comes on when key is on not running.

[Michaellatini]

Oops. Light stays lit when running.

[VW_Jimbo]

[Michaellatini]

It’s wired the way it was shown to me. It ran fine for 1500 miles but, that’s not good.

[Michaellatini]

Are you thinking that the way it’s wired could be causing the alternator to give up quickly?

[VW_Jimbo]

[Michaellatini]

Ohhhhh I’m not thinking! It was wired that way because the red light in the drawing was an LED. The incandescent light was to trigger the alternator but it did not work so I change the LED to another incandescent. I need to remove the second bulb. Yeesh!

[ashman40]

From the diagram I gather there are two (2) GEN lamps? The red circle is the dash mounted GEN lamp? Is it an LED bulb? The second bulb marked "ALT/GEN LAMP" is that an LED or incandescent bulb?

What are the two bulbs wattage ratings and are they LEDs?

The stock alternator was meant to have an incandescent 12v/2W bulb in the circuit to the D+ terminal. As an incandescent bulb, current would flow in either direction lighting up the bulb. When trying to use an LED bulb for the ALT/GEN lamp you run into a problem as many LEDs typically only allow current flow in one direction as they are physically diodes (some of the larger LED bulbs are not polarity sensitive). The above diagram looks like an attempt to use an LED in the dash but still provide the full 2-way current flow thru the secondary (incandescent) bulb.