alternator overcharge

[dingo]

A much belated roundup and synopsis: something is frying my voltage regulators.

I got tired of replacing alternators and regulators...so i decided to re-arrange the mounting brackets and slipped in a modern Denso japanese alternator with built in reg.
It worked great for about a month, then one day 'no charge'...finally diagnosed it down to a burned out regulator. So thats where I am at.

I can say that ive learned a huge amount about diagnosing charging systems, both Type A and type B. Also Ive discovered that the Jap built Denso far exceeds the clunky functionality of the Bosch alternators,( and that includes some fairly modern Bosch alts). They are smaller, lighter and put together in such clean, high quality, logical fashion. German engineering ? good, but a distant second...IMO.

[Amskeptic]

A much belated roundup and synopsis: something is frying my voltage regulators.

I got tired of replacing alternators and regulators...so i decided to re-arrange the mounting brackets and slipped in a modern Denso japanese alternator with built in reg.
It worked great for about a month, then one day 'no charge'...finally diagnosed it down to a burned out regulator. So thats where I am at.

I can say that ive learned a huge amount about diagnosing charging systems, both Type A and type B. Also Ive discovered that the Jap built Denso far exceeds the clunky functionality of the Bosch alternators,( and that includes some fairly modern Bosch alts). They are smaller, lighter and put together in such clean, high quality, logical fashion. German engineering ? good, but a distant second...IMO.

So even with the Japanese alternator/regulator combo, your vehicle's electrical system has managed to toast the above?

Let's get outside of the box. Is there anything going on with the rest of the system that could annoy the charging system? Some weird incorrect polarity? A short in a main cable? Do you have custom wiring/accessories? WTF?
Colin

[dingo]

i got this email today from a Denso rep:

If the light remains on brightly when the engine is running then the regulator is probably faulty, or the rotor could be short circuiting

If the light glows dimly while the engine is running, then there is a diode or two blown in the rectifier

If you replace the regulator, be sure to check the rotor current draw with an ammeter. It should be around 2.5 to 3.0 amps maximum. Any more than that will kill the regulator


in my case, the dash light comes on normally with Ign ON, then with engine running, dash light is mostly OFF, but occassional flicker of 'dim glow'

I have checked out all the diodes and they seem fine (there are 8 of them in a Denso..havent figured out why)

next i have to figure out how to check 'rotor current draw'....

[Hippie]

next i have to figure out how to check 'rotor current draw'....

I bet somebody here will tell you the wire colors and all that from memory, but I'm going to say that you should just be able to put a normal DC ammeter in series with the rotor. That's where the regulator feeds current into the alternator...it goes through the brushes and slip-rings to magnetize the rotor. The more current to the rotor, the more alternator output, there, then, now.

[dingo]

next i have to figure out how to check 'rotor current draw'....

I bet somebody here will tell you the wire colors and all that from memory, but I'm going to say that you should just be able to put a normal DC ammeter in series with the rotor. That's where the regulator feeds current into the alternator...it goes through the brushes and slip-rings to magnetize the rotor. The more current to the rotor, the more alternator output, there, then, now.

OK, Thx..thats fairly simple,then.

By the way, Type B (Bosch and most others) reg feeds current in via Brush#1 and out brush#2 to ground

Type A : B+ voltage goes to brush#1, then brush#2 passes it to DF and Reg regulates the amount of grounding .

[Hippie]

It doesn't matter whether the ammeter is on the hot or ground side, it will measure whatever current in the line you interupt with the meter, just so long as the black probe is on the most grounded side.