alternator issues

[narfire]

OK my alternator (65amp variety) was not charging the battery. It showed 9.4 volts at the stud when rpm was 2500-3000.
Bought a replacement volt. reg from a specialty store in Penticton. Old reg had very worn brushes.
I have yet to install the old alt with new reg but is there anything else that might cause the discharge to be 9.4 volts. The alt seems good, I cleaned up the insides and the shaft does not have any play.
Thanks eh
Chris

[spider2081]

Did the alternator out light light when you have the key on and the car not running. If the bulb is bad or disconnected the alternator can not charge. Also I believe people have found you cannot replace this bulb with an LED and have the alternator work correctly

[KevAndAndi]

My alternator light has started to glow slightly when the engine's running. (It lights brightly before starting when the key is turned to the run position.)

An initial test at the battery indicated the alt may not be providing charging voltage. I have to check the voltage at the alt stud.

How much is a new voltage regulator versus a new alternator?

[So Cal Mark]

a dim glow usually indicates a bad diode rather than a vr problem

[narfire]

How much is a new voltage regulator versus a new alternator?

I was soooo lucky after a week of not so much.V reg. cost me $12.10 taxes in CDN A replacement alternator was going to be a couple hundred CDN and a day wait.
I'll install tomorrow am and see how we do. Too hot, all of 98 deg F right now. time for a swim in the lake...

[spider2081]

I think the alternator out light is fed power from the "Hot in start and run" circuit of the car. So the power side of the light should have battery voltage on it when the cars key is on and the car is not running. The other side of the light sees a ground through the alternators stator circuit. When the engine is running this wire then has voltage on it. As this voltage approaches 12 volts the light goes out as there is voltage on both sides of the light. You can measure the voltage on the light wire at the alternators "D" terminal. Note: There are 2 similar terminals on the alternator the "D" terminal is for the Alt out lite and the other terminal is for the filter capacitor. The alternator will not work properly if the connections are reversed.

[seabeelt]

+1 on the bad diode for a dim alt light. Went through this a year or so ago. Alt was providing sufficient voltage to provide charge, but the darned light was always glowing. Only way around that is a new alt, unless you are good at repairing alternators

[narfire]

The diode is internal? I have a little black thing ( about 3/4" square 1/4" thick) screwed onto the back of the alt with a lead plugged into a spade fitting on the back. 65 amp Bosch alt

Chris

[narfire]

Going to be a good day. Not only is my name NOT in todays obituaries, I just hooked the alt. and battery back up and tested at 2500 rpm.....wait for it....14.2 volts discharging..... yea... Ok back to sawing timbers now.....
Chris

[spider2081]

Great news both about the obituary and the alternator. Its sort of common here for people to unnecessarily change alternators and starters. Nice to see you weren't one of them.

[courtenay]

That is good news, Chris. You were due some.
I had a good day too - the fish gods smiled on me and I actually brought a nice coho into the boat!!
Cheers,
Bruce