What are symptoms of bad alternator diodes?????

[denali804 10+ year member]

What kind of symptoms would a person have if the diodes in a vehicles alternator are starting to fail?

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[fbi90909 5,000+ posts]

no charge?

 

[Haunz 10+ year member]

Won't charge properly & major AC ripple.

 

[SlowCamaro 10+ year member]

dimming lights

 

[TurdFergueson2 5,000+ posts]

What's your issue. I had one that would slowly drop the charging voltage. Started off in the 14s, dropped in the low 13s. Put my old one back on and I'm am averaging 13.8 or a little higher. Crazy thing is it never dropped in the 11s, just low 13s with everything low. 2 batteries both new and like 2600 watts of power.

 

[snoopdan 5,000+ posts]

a leaky diode will tend to pull down the battery, but it's mostly because you're using the engine while it's sick.

 

[denali804 10+ year member]

What's your issue. I had one that would slowly drop the charging voltage. Started off in the 14s, dropped in the low 13s. Put my old one back on and I'm am averaging 13.8 or a little higher. Crazy thing is it never dropped in the 11s, just low 13s with everything low. 2 batteries both new and like 2600 watts of power.

Voltage is good and no dimming. I'm getting a slight fluttering from my sub and sub amp with volume down. If I touch it I can feel it moving slightly. It's pissing me off. Thought it was a ground or loose wire issue but all of that checks out good. Also changed sub amp and sub and still have the same issue. I thought that noise would be a side effect of leaky diode (ac ripple). I took it to advance to have them test it and I started asking about leaky diodes and the dood said alternator is either good or bad, he tested and he said it was good. I have the stock alternator around here and will put it back on to test if it ever warms up and stops raining. A rebuilder said he could bench test it if I take it off the truck. Thanks for the help.

 

[badvlvo 10+ year member]

Lower than normal voltage, ripple current, low battery charge.