New electric fan killing battery

Is this the wiring diagram for your Alt??

 

Affirmative KC, that looks correct.

 

OK since the charge light is always on of course means it isn't charging, but real reason is because the bulb is provided a ground path through the diode trio and on to lower section of rectifier bridge... Assuming the regulator is OK(I'd say likely if rotor is energized) and stator isn't shorted/open, about the only possibility is the upper portion of bridge is open, not allowing a voltage output which places a positive voltage on ground end of charge lamp... It isn't going to light when there is positive on both ends of bulb... Sooo looking at your previous posts I'm gonna say the upper three diodes in rectifier bridge are open or have a connection problem...

With stator disconnected, check each diode section of rectifier to be sure it shows resistance in one direction and open with meter leads reversed... Use either Rx1/2 or diode test if they are separate functions...

You can also try full fielding which would be to ground the connection from rotor at TR1... If that starts charge it's a regulator issue... Unlike the Ford alts, doesn't appear that point is accessible from outside case??

 

Today I did re-check each of the six diodes on the bridge and they seem ok (flow in one direction and not the other, tested both banks and had same result). Diode trio passed same test.

The one item that I haven't really been able to test is the used regulator that I put in. Odd thing is....that regulator was working when I freshened up the unit about 4-5 years ago. I thought the Delco units were potted and not susceptible to "shelf wear/moisture". Hmm, so there may be the possibility I swapped a bad unit for another bad unit.....

I have the unit disassembled in a box now, but there is a hole in the back to full do a full field test. I'm booked until next weekend....so will be a while until I can proceed.

Thanks for the assistance, much appreciated.

I'll update if any new developments pop up (ie: found something overlooked, gave up, went nuts and strapped an explosive to it, etc. etc.)

 

is taking it to a alt. shop not an option...
if you think it's the alt, just bolt on another one and see if there's a change (charge)...

 

Well I can't speak for Comet155 but not for me... Last year I tore the 3G apart on my old F-150 that charged but appeared to be full fielding it's self at higher RPM's(voltage suddenly jumped to 16v)... Found a solder connection loose on rotor that was being forced on to case that was effectively full fielding the unit... Reinforced & resoldered, it's been fine...

I went through the alt on my Comet just prior to running engine on a friend's test stand... That is a rebuilt unit that charged fine when last used(5-6 years prior), all seemed OK, was dead as the proverbial door nail with engine running... Once back home I checked it again, regulator was dead...

 

I'm too stubborn plus annoyed that I haven't solved the problem.
Don't have a spare, I chucked the old 1G years ago.

 

3G
3G
3G
3G
3G
3G
and your problems are solved! ! My voltage regulator use to get so hot it would take the paint on the inter fender off !!! Not any more. 3G charges GREAT !!!!! Less parts to worry about

 

Yes, I hear you 74. It's just I've had this thing for almost 2 decades. It has worked pretty well (up till now) and it's easily rebuildable (up till now)........ (not so easy with the 3G due to the soldered stator leads and all).

A warrior doesn't like admitting defeat (or the hands and face for that matter).

 

I hear you but once you rebuild one it so simple you'll say to your self why didn't I do this a long time ago

 

$20 alternator from junk yard and call it a day.

 

Full field test: unit is operational. Regulator #1 was toast. Old replacement "non domestically manufactured" regulator #2 also toast resulting in several ghost chases.

Installed new "genuine" domestic Delco-Remey N.O.S. regulator , reassembled everything and fired her up.

Charging like a raped ape again. It's Miller time!

 

Appreciate all the input, thank you.

P.S. Before reassembly, I gave it the ole` electron microscope look over. Found a breach in the insulation on one of the stator leads. Looks like it was shorting against the case. The wires were too stiff to shove 'em inboard, and didn't want to pound em'...

....So I relieved a bit of the inner case with the Dremel. Put some "liquid electrical" tape goop to reseal the wire.
Don't know if that partially contributed to frying the reg, but at least it's repaired.

 

I may have missed it, but where did you get your alt from? I have a power master 1 wire 100 amp, with nothing on, it'll charge the battery up to 14.5v. Once I turn on anything, the voltage drops and continues to drop. Driving at speed I'll get 12.2, at idle it goes all the way down to 11.8. Park turn everything off the voltage slowly comes back up. After about 20 min, it'll be back to 14.5. I've checked grounds, replaced the feed wire from the battery to the fuse block with 8ga, have a 4ga to the battery, even added a ground to the alt. and replaced the battery. I have a 250 in it, will the 3g alt fit?

 

Of course you have to tighten the alternator belt back up after doing all of that work. I think I figured it out.