Alternator Issues

[1450-ranger]

We are running a Jeg's 130 amp 1 wire alternator on our 302. The alternator is not charging at all, and its a newer alternator (400 miles). As ironic as this sounds, is there a deal with the wiring on a 1 wire alternator. Through BS'ing with other racers, some say that loading the alternator + wire (with a small light) will kick the voltage regulator on; thus telling the alternator to charge. That hasnt worked. We are stumped, and we have a race Saturday. The alternator is at the shop getting tested tomorrow.. At this point we are assuming the alternator is good.

Any help would be appreciated, thanks

Jon Mc
1497

[desertracer]

Not sure what you have as far a pulley's on the motor, but we chased something very similar to what you are saying. Our water pump pulley was only slighly bigger than the alternator pulley but we figured that running at 4-6k rpm would be enough. After pulling alternators on and off we discovered it wasn't spinning fast enough to ignite the field and kick on the alternator. Just a thought...

[1450-ranger]

Smaller alternator pully and it fixed the problem?

[desertracer]

We ended up going with a smaller alternator pulley and larger water pump pulley. Our motor builder and everybody could not figure the problem out for the longest time. We would sit there and rev the motor to about 7k and then it would kick on but after a while it would shut off and not charge. It was so confusing because we went through like 5 alternators (all single wire) and on the test bench they all worked perfect. In the end we figured you need a ratio of about 2:1 or greater to get it to work right. so 6'' water and 3'' alternator, not sure on that exact ratio but that is about what got ours to work well. That was on our old motor, now we run factory gm with no problems.

[1450-ranger]

Interesting, that makes alot of sense, never considered that. Thanks for the input.

[racetrash]

most 1 wire alternators don't start energizing until 1200 to 1800 rpms. we have had problems like this on some of the hot rods, when they are just idleing around a cruise weekend or something

[1450-ranger]

Thanks for the input guys

[1450-ranger]

More info..

There are 2 leads(tabs) under a grommet in the alternator, one noted by "R" which is positive while the alternator is spinning, and one noted "S" which has no charge.

While this is a 1 wire alternator this raises some questions.. Any help guys? Thanks

[1450-ranger]

Its good to go, thanks all the input guys, and thanks to WoodyW(good guy, great fab) for the help too. shameless plug

had to power the lead with a switch and it started charing.