andrewsfm

iTrader: (3)

I just installed a 220A high output alternator in my car, and the higher the engine revs, the more my headlights fluctuate to the point it's very noticeable.
I hooked up a graphing multimeter to the battery, and found that the output from the alternator looks like a sinewave at higher RPMs which is why my headlights go up and down in brightness.

Any suggestions to what might cause this?
I have 0AWG positive and negative runs from alt to battery to amp

Check my signature for any additional details I didn't include.

Sasha

iTrader: (10)

I would bring it back to the shop, where they did the work.

andrewsfm

iTrader: (3)

There wasn't really any work done at any shop.
The alternator was installed by my friend who's a licensed mechanic.
The upgraded wiring that I added originally with the stock alt is still in place.

Sasha

iTrader: (10)

Damn it, that is why I am so cautious about getting an HO alt from Iraggi, who just said no problem to my request and gave me quotes. But I have my reservations, and wanted it done in T.O. from start to finish, cause every alt guy here tells me it cannot be done on my car. I drive a VW, and that is just tough bricks for me. I don't want to hear somebody in the US to tell me "no problem", take my money, and leave me to sort the crap out if need be. I cant help you, but I feel your frustration.

Haunz

iTrader: (3)

sounds like there is a problem with the rectifying diodes... unfortunatly you will probably have to pull it out and have a diognostic ran on it by an alt shop...

JL Stomper

I know a guy with the problem and there was nothing wrong with it when they had tested it.. The alt shop said it was somthing in the car shorting out and causing it to that. that was last week and still has not got it fixed.

macguyver

Smart money is on the rectifiers.

Alternators produce AC (hence their name), and the output must be converted to DC via rectifier diodes. These diode are not clean, they drop 0.7V over each diode, and are prone to thermal problems at high current. If they are toast, or are being overloaded, they can and will pass AC back onto the system. This is what your loggin meter picked up. Likely it's not pure AC, but rather mostly DC with some AC mixed in. This is why your lights will increase and decrease some, but your electronics have not been fried yet. You might only be witnessing the variations around 0.7V.

Take the alternator back, and make sure they load test it. Simply measuring the rectifier with a DMM is not sufficient.

andrewsfm

iTrader: (3)

So you guys say rectifier over regulator?

The multimeter shows no significant real AC voltage present.

macguyver

If your alternator's output looks like a sine wave, then it's AC. DC will be a straight line, or pulsed half-waves that resemble 1/2 of a square wave.

andrewsfm

iTrader: (3)

I'd have to say it looks like a distorted sinewave (rising faster than falling) with flattened valleys and peaks, but definitely not square or sharp edged.