alternator voltage fluctuations

Just thought I'd share with everyone. Something I found out today on my dad's jeep.

He was trying to install a Delco 10si alternator instead of the generator and was having issues with the voltage fluctuating between 12 v and as high as 19 volts. it was fast and erratic.
It finally wouldn't even start and its been bugging him all week so I finally went over there with some parts from wimpy to see what was going on.

He put a new coil, a set of points in with my condenser, cap and rotor, and coil wire. It started and ran fine. the alternator also was working just fine. Started out about 13 v and once it revved up leveled out to 14v steady. So once that was going good we started swapping his parts back onto the distributor untill the condenser was left. He was going to give me some money for another one since it was in, but I need it to plow tomarrow because of a house showing. So we took my condenser back out and put his back in just for the fun of it.

The alternator was bouncing all over the place again. Somehow that condenser is screwing with things and causing some kind of feedback or something to the voltage regulator.

Just thought this may help someone in the future...

 

the only reason we saw the voltage fluctuate was because of the new install of the alt. didnt check on mine but my condensor worked fine and we swapped his in and problems came back. he's going to replace the spark plug wires too. someiow inducing a voltage spike back thru the coil and affecting the voltage regulator?
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im thinking the condensor was doing something to the regulator to make it "think" it needed to crank the output of the alternator up to charge the battery. thats why it was going up to19 volts
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I'm with you Walt, makes no sense whatsoever- no way should a condensor, whether shorted or open ,affect the voltage regulator. Shorted = no run, open = fried points. The only thing I can think of is that.. no, wait, that wouldn't do it either It could be there's something strange about how the alternator is hooked up but it would have to be very strange.

Anyone got any theories?

H.

 

well. he put a new condensor in and it didnt work. ill type a better response when i get a chance at work-keyboard
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I understand what your saying about the coil. Just thought maybe if the condenser was shorting to ground it was messing with the regulator.
He's getting a new set of plug wires today. The old ones are about 2 years old and when I measured the resistance on them it was .1 ohms. My coil wire I brought was about 4k ohms. maybe the low resistance in the wires is causing noise to the regulator...

The other thing he's got is the battery feed to the alternator output goes thru a kill switch, thru the dash ignition switch, back out to the alt. Its alot of wire. He has bypassed this so a jumper wire went right from the + battery to the alt output. But the rest of the wiring was still hooked up in the dash. He's going to check under there and make sure there isn't any loose connections or chaffed wires causing a short to ground. Told him if he didn't see anything disconnect it all and just go basic with battery to alt, alt to starter and jumper wire to ignion coild. Trying to see if the wiring's a problem somewhere.

The grounds should be good. He has the battery - going to the engine mount, same stud he's got this monster ground braided cable about 1 1/4" going directly to the back of the alternator and bolted to the alt case. He cleaned the battery terminals and got a new positive cable also.

The coil is new, hooked up + to ign feed, - to points. coil goes to the dist Internal resistor, no external ballast resistor.

makes me want to think its somehow distributor related. Just becuase thats all we really messed with, and it WAS working fine when we had my stuff on and all the way up till he put his condenser back in. Unless we bumped something around it and didn't realize it.

He's getting the plug wires today and going to check the wiring also so I'll check back in and let everyone know what happened.

One other thing. The 2 wire connector that plugs in the side has a resistor going across both terminals. Is this necissary? I had my spare apart last night and noticed an internal resistor that looks to be doing the same thing. Too much resistance across the two terminals?? I had disconnected it when we swapped parts around and thats when it worked fine. But it was also hooked back up before we swapped condensers and it was working fine once with it connected.

 

copper core plug wires don't work good with modern electronics.........

thought the .1 ohm reading was goofy. My coil wire must have helped out enough to get it working.

He replaced the wire set and no problems anymore.

 

That would be the one.
You know what, that makes sense. I'll bet thats what it is. I just assumed it was a resistor.