'68, 350, 100amp Powermaster Alternator (One Wire with optional provisions for Exciter), March Performance Ratio Pulleys...

This has been the biggest absaloute pain in the ass. When I bought the car, It had a painless 18 circuit camaro harness in it, powermaster 100amp chrome one wire (optional exciter) Shortly after getting the car home, one day it just starts draining the battery everytime I parked her overnight. At this point I assumed the increidbley butchered painless harness (single wires being spliced 3 times, 3 diff colors) must have something to do with the battery dropping its charge overnight. I get the alternator checked out, alternator is toast, replace it with the same Powermaster unit only a Polished, not chrome unit. Next, replace the ENTIRE wiring harness with a BRAND NEW Painless 18 circuit,

Battery still drains overnight. (or when it sits for 8 hours)

I am now $60 (conicidently tow truck driver owned a '68 too, gotta love em) poorer, and spend my st. pattys day stuck in front of a bar trying to figure out WTH is wrong with my car.

Fellas, even without gauges, or accessories, this cars battery drains (but now only when driving). When I got my new march pulleys, I moved the alternator to the passenger side, and ditched the exciter wire per advice from randy @ painless. Now march performance told me to go with the high water flow pulleys if this is a daily driver, but i was adviced that If i turned my idle up to around 850-950 I would be perfectly fine, I did so, car runs great with the higher idle, BUT MY BATTERY DRAINS after about 10 minutes @ idle. WHAT IS HAPPENING? I rev the engine to around 2500+ to get the alt to start charging, but no dice? Keep in mind this EXACT same electrical problem persisted before I changed pulleys, my old vbelt did this too.

ADVICE! PLEASEEEEE I have disconected every accessory on the car, still drains! on my 5th Optima Red Top, and frankly don't have a clue, all that is running is the alternator and my MSD.

help appreciated, since I am at my wits end

your alternator ain't charging... maybe that exciter wire would help?

At dusk, just because you can see it better, remove a battery cable and insert a test light into the circuit.

The light glowing will show a circuit still being "ON." As you disconnect other circuits, the light should go out, at least until you get to 'battery-on memory,' ie, clock, radio, etc.

If the light is still on, and everything else about electrical circuit is disconnected, I'd disconnect the alternator. If the diodes and/or internal wiring is hosed, the circuit will be closed. There will be a very slight glow of the light if alt is good.

All right, so you've found the discharge problem when the car is not running. Now to find the no-charge when running.

A voltmeter across the battery terminals should show a charging voltage of less then 14.5 volts. Since you've moved the alt from drvr side to pass side, and converted to a 1-wire, the ext reg connector should have a jumper about the two outside terminals. There should also be a wire from the BAT post on alt to the right hand terminal. #8 AWG wire should go from the alt BAT post to the battery positive terminal. There should also be a good circuit of ground from the battery negative post to alt case.

You can look at Mad Electric's site and find the wire diagram for conversion from external reg to int reg 3-wire & 1-wire alt.

I personally would do a 3-wire than 1-wire.
another shadetree method of checking the alt charging is with the engine running, place a screwdriver flatly across the rear shaft bearing, Ig the alt is charging, you will feel a magnetic pull when pulling away the screwdriver.

Hope this helps.

another "shade tree" method would be to pull either battery cable off with the motor idling. If it dies, the alternator is not charging at all.

thanks guys! off to costco to get my new battery, (dead cells, yet again) and ooo if this alternator is screwed im going to be PISSED (bought it in july, havent driven the car more than 100miles since)

anyway, you guys're awesome, everett, jim smile.gif

p.s. Jim no matter what I did with the exciter wire attached, battery would die if I parked, it, I was at a point where everytime I stopped off somewhere, had to get out, disconect the battery, got VERY old.

anyway, thank you guys, SO much

Was just thinking of this today, I'm running Dual SPAL fans, MSD & Gauges, could the Fans /MSD / Fuelpump & Gauges draw more than my alternator is able to put out?

40amp fuses on each fan.... 15amp fuse for fuel pump, MSD, who knows

you guysthink maybe the problem isnt that the alt isnt charging but that @ 900rpm+ idle with both fans engaged it isnt producing enough juice? Don't have a multimeter / volt meter to test this yet, but what'yall think?

Certainly could. Do the screwdriver trick, this will tell if alt is working.

But, what about the discharge when parked?

this is probobly going to sound rather newbish, but.... discharge?


are you saying the alt has a discharge when it stops charging? :-\ explain please