Fried Alternator Wire

[patrickt]

Dan, my OEM AC-Delco 60 amp alternator is only $40 from Amazon. My puller fan draws 16 amps, my pushers draw 8 amps, the lights draw 10 amps, and the ignition draws 1 amp per thousand RPMs.


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[DanEC]

I think this is a Powermaster 65 amp alternator from memory. They are pretty common around here at most FLAPS for not much money. I'll check on one tomorrow.

[patrickt]

Originally Posted by DanEC

I think this is a Powermaster 65 amp alternator from memory. They are pretty common around here at most FLAPS for not much money. I'll check on one tomorrow.

I've measured the current on each circuit of my car. These cars hardly use any juice at all when running. When I'm "cruising" down the interstate during the day, none of my fans are running, my lights are all off, and the total amperage drain on the system is less than four amps. That's like a 60 watt light bulb. That's it. In town, in hot weather, only my puller fan runs -- so my total running draw is under twenty amps. Unless someone has monster-killing fans, a huge stereo, heavy duty electric fuel pumps coupled to a microwave oven in the trunk, you barely need an alternator at all.

[RICK LAKE]

DanEC Dan first off IF your motor is running a 65 amp alt without under driven pulleys, this output is fine. Here's a basic list of draws in the charging system in amps. It's not perfect but close
Electric fan (1) high speed 8-16 amps
twins fans in front of car 7-15 amps
wiper motor depending on speed and load 5-12 amps
lights headlight, (Old style) 2-6 amps
Stock ignition with oil coil about 2-4 amps
rest of electrical draw about 2 amps running max.
The biggie, CHARGING of the battery, upto MAX of the output of alt.
voltage may go to 16.0v depending on battery and condition
The wiring setup for the cobra was to run a 45-60A alt setup.
Today is different with alot more power users in the car
MSD ignition system may pull upto 10amps alone
Electric fuel pumps depend on unit 15-18 amps
Some guys have AC in their cars, add another 30+amps
High power HID lights, They are all over the place with load.

At idle you need about 30 amps to power the system and recharge the battery. Any thing less and you are looking for problems. I went through this many years ago. Main problem was underdriven motor pulleys and killing the battery at idle. I also started to melt the end at the Alt, just like yours. The worst part was the insolators on the amp gauge in the dash. They where melted too. I couple of guys here have melted there wiring harness and it not a good thing. You could loose the whole car.

Here's what is in my car and what I did to fix all the problems,
PAperformance sells a couple kit for cobras with a 95 amp setup. This is more than enough power for all the acc to run at idle. It has a old style regulator box and Alt. Change 2 wires and you are done. The other issue is to replace the Amp gauge with a volt meter. The 2 wires that are connected to the guage should be spliced togeather and add 150 amp maxi fuse to protect wiring system. Swap the pulley off old Alt. Been running this system for 5 years and no problem. Still can run the under drive pulley from march on the crank shaft. I went to a 1-1 ratio with crank and water pump for another problem. My system runs 35-38 amps at idle and 14.12 volts on the gauge. when all the electric is on still in the 12.7 volts.
Power load to my car, FI system with injectors, 2 fuel pumps (electric) MSD ignition system with HVC coil, 6 cooling fans, 3 for the motor, and 3 for removing hot air from under the hood and down the trans tunnel. Total load is about 48-52 amps depend on temp of the day. This can be a 2-4 amp extra.

I would check out the wiring behind the dash at the amp meter. Make sure the insolators are not burnt or off color. Any possible thought, REPLACE THEM or the gauge.

Only other thing I did was add a fusible links to the main power wires. If you have a dead short they will save the rest of the wiring. Need about a 125 amp. This is what I run. Gives piece of mind. Good luck Rick L.

[DanEC]

Thanks Rick and Patrick. My ERA is a pretty rudimentray Cobra replica - HD puller fan, points ignition, no stereo, mechanical fuel pump, etc. I do liike to run the lights when cruising around even in daytime. I used an alternator with a part no. for a 1970 428 Mustang (probably cross references to a lot of V8 Fords) and it seemed to be doing a good job until it decided to take advantage of a loose connection to change careers and become an arc welder.

[FWB]

Dan, i'm sure you have the problem licked.
just an observation from the pic of "the fix" you posted.

the eyelets seem to bottom out on the black, what i call "insulator"
giving a false sense of tight. as the wire cycles hot and cold it may shrink expand, get hard or all of the above, and may slowly be loose by itself.
i would place a washer on the alt stud first then attach the eyelets on the stud, when you then tighten the nut it will firmly bottom on metal and not catch the black insulator. i had to do this on both my powermaster starter and my one wire alternator

[patrickt]

Since you're replacing the wires, connectors, and alternator itself, once you get the new stuff in you should take five minutes and perform a voltage drop test on the charging circuit (both positive and ground). It will tell you if you have a problem anywhere along the circuit. The picture that I'm posting below shows a 100 amp charge, so the potential difference between battery and alternator is acceptable at 700 millivolts. For your 65 amp alternator, I would only expect 400 millivolts or less both on the positive side and the ground side. Dan, I know you hate any sort of electrical test, but this one is not only the easiest, but it's the best. Just put your VOM's leads as shown, with the car running, and measure the voltage just like you see on the pic. If you register a number that's larger than .4 volt, on either the positive side or ground side, then you have more work to do. If it's less than that, all is well. You can do this.