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Author Topic: Headlight Problems  (Read 16448 times)

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Fierofool

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Re: Headlight Problems
« Reply #15 on: April 05, 2017, 01:09:01 pm »
I was thinking that output voltage should be about 13.5 to 14 volts, but I'm not sure.  The battery is just a storage point for energy when the engine isn't running.  I've actually installed a battery that wouldn't take a charge into a car just to complete the circuit, then bump started or jumped it and it would run.  I've been told it's not good to run a car without the battery connected.  I think some cars won't run if you disconnect it.  Probably to avoid damaging the alternator. 

I metered 19.1 volts on the old alternator.  By far the highest voltage I've ever seen.  Previously, one on the Lil Duke Coupe was putting out 17.  The headlights flashed like a motorcycle's daytime running lights as the regulator tried to adjust.  It did damage the battery, even at 17 volts, and I had to buy a new one.  And a new alternator. 
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TopNotch

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Re: Headlight Problems
« Reply #16 on: April 05, 2017, 03:01:04 pm »
Typically, the alternator has all kinds of spikes and RF garbage in it's output, and the battery smooths that stuff out. That's why it's not good to run without a battery. Those spikes could damage your ECM.
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Drewbdo

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Re: Headlight Problems
« Reply #17 on: April 10, 2017, 12:18:54 pm »
Quote from: tshark on April 04, 2017, 07:39:06 pm
I was wrong, too, about the headlights not taking 19V.

I'm glad to read that the problem has been solved.  I'm a bit confused on why the previous alternators didn't solve the problem, though.

Maybe he just got unlucky enough to have a couple of bad alternators in a row... found that one the hard way.  ;D

Had a minivan. I noticed that the headlights and interior lights would flicker, the A/C would stop, and sometimes, if I stepped on the brakes, the radio would shut off. The parts house tested the battery and charging system. Said it was a bad alternator, not putting out enough power.

Replaced it. Shortly thereafter, same symptoms. Replaced it again. Replaced it AGAIN. Thankfully, after the first one, it was all under warranty from AutoZone.

It's been a while back, so I can't remember if I used remanufactured or new ones. However, I will say, I got really good at swapping alternators on that van. :)
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GTRS Fiero

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Re: Headlight Problems
« Reply #18 on: April 10, 2017, 09:04:53 pm »
Quote from: TopNotch on April 05, 2017, 03:01:04 pm
Typically, the alternator has all kinds of spikes and RF garbage in it's output, and the battery smooths that stuff out. That's why it's not good to run without a battery. Those spikes could damage your ECM.

I guess this wouldn't work on a car, but elsewhere, I've used capacitors to even the voltage out.  My mind is only coming up with bridge rectifier, but that's the wrong thing.  I had a little circuit that split up the signal, and removed all the garbage.  It came from a cheap old TV.  Someone else used a home-brew setup with similar technology to a noise-canceling headphone.
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