Tuff 150 amp alternator

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Eric Pearson

Eric Pearson

73purpule duster
FABO Gold Member
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Good evening everyone, I have a tuff 150 amp alternator installed on my Duster. I have converted my charging system to the Mad Electrical wiring set up. So my question is does anyone have an opinion on why my volt meter starts oscillating above 1k rpm. When I add more rpm’s I notice that my lights start to pulse in sync with the voltmeter. I have checked the connections, and verified 12 volts to the alternator. Replaced the voltage regulator. Any thoughts on this would be appreciated. Thanks
 
Bad diodes in the alt can do that

The alternator produces AC the diodes convert it to a form of DC.

If some diodes are bad the DC can become more like AC and pulse

Most auto parts stores have a tester they can put in the car that can see bad diodes
 
This can be "worse." First we need details, !!!DETAILS!!! on the system.

1...Just what is a "Tuff 150A alternator?" Who makes it and what does it use for a regulator

2...How EXACTLY is it wired? How large is the feed to the battery? How is the alternator grounded, and what is the path to the battery ground

3...How large is the charge wire and what exactly is that path?

Oscillation in the old days could be caused by a electro--mechanical regulator, which you do not have, I'm sure. It can also be caused by various wiring problems, such as poor connections, improper grounding, and TOO SMALL conductors (same idea as bad connections) which cause voltage drop in the system

AND KNOW THIS!!! 150A is nothing to sniffle at. You have a WELDER there. You have something that can burn that entire car to the ground.

It could be caused by electrical problems in the VR or alternator, but less likely.
 
150 amp. That is about 120 amps more than a stock non-AC car. Do you have add-on accessories drawing that much current?
 
If you have a GOOD DVM, one that measures TRUE RMS. measurer the DC voltage at your diodes, then switch your DVM to AC voltage. In a perfect world it should measure 0 VAC, but it won't you should get a very little VAC, Depending on your set up if you have a significant VAC then the diodes are leaking too much.
Disclaimer: I have been out of the industry for over 25 years and just am now just starting to heal from a bad health crisis since Nov 17th. So I can not think of the VAC you should be worried about. If I find it I will amend this post
 
I got a tuff stuff 60a alternator this summer and the damn thing wouldn’t charge at idle. Even with their voltmeter. Failed a field test. Got a new one and had it tested before I put it on the car, failed again. Went to another shop and tested it there just in case, failed. Still heard nothing back since august. If they warranty it, you still have to pay shipping
 
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