1979 xs1100 stopped charging

[roger]

I rode the bike and it stopped charging, the tachometer and head light quit working. I cleaned the wires behind the fuse box they were in pretty good shape. I ohmed the rectifier it seemed to be ok, I tryed the metel gauge to the alt it wouldn't stick. I took the cover off the alt and the magnet is real weak. is there a way of testing it. thanks

[jkorn]

Look for a loose connection. There are many of them in that system.

[roger]

I was doing some test and found i have 12 volt on both the brown and green wire behind fuse box, I read if you have batt volt on green it won't let alt charge. what makes it have 12 volt?

[DEEBS11]

The most likely cause of a charging failure would be a bad regulator or the connection between the 3 phase stator and the regulator is open due to bad connection. You probably ran on battery until it went low. I'm sure the magnets are fine. You should have continuity between all three legs of the stator but none of them should have continuity to ground. An open leg or a leg shorted to ground would cause no output. I would be looking at connections and the regulator.

[roger]

The most likely cause of a charging failure would be a bad regulator or the connection between the 3 phase stator and the regulator is open due to bad connection. You probably ran on battery until it went low. I'm sure the magnets are fine. You should have continuity between all three legs of the stator but none of them should have continuity to ground. An open leg or a leg shorted to ground would cause no output. I would be looking at connections and the regulator.

I have continuity on all 3 wires and none to ground. I unhooked the green wire just to see if it would charge, it didn;t help. it said it should have low voltage on it until the motor starts then the volts come up.

[Socer4m]

maybe keep it simple
1. charge up your battery with a battery charger fully
2. check the battery voltage not running, should be around 12v. with any simple voltmeter
3. check the battery when running, and revved a bit, should be around high 12v, 13v
4. if both check out, your battery and charging system are good, also clean the ground connection from the neg. battery terminal to the frame,,,,has caused many a member to go crazy, keep us updated
5. good to see Motoman checked in,,,he is the man for xs advice......

Mike in SanDiego and Pa

[roger]

has anyone got a good regulator they would sale

[DiverRay]

Try herehttp://www.oregonmotorcycleparts.com/ Tony has been a member for years, and builds a GREAT reg/rec for our bikes. Not cheap, but worth the money, IMHO.

[roger]

ok I wasn't sure what the problem was so i got a cheap after market regulator to see if it helped it. when i started it up the head light came on and the teck started working. only problem it only charges about 12.8 volts, do you think that will be enough? thanks

[DiverRay]

You probably need about 13.4V to keep the battery charged. You DO need to check the voltage with the engine running at least 2,500rpm's. Again, this is the part you need to spend a little money on.OEM these would do 30 amps max at about 3,500RPM. The one from OMP will do the 30 amps at about 2,800RPM, and has better diodes that can take a little more abuse.

[DEEBS11]

Your cheap regulator is probably Chinese. It very well could leave you on the side of the road at the most inopportune time.

[cajun31]

I second what Ray has told you about Geezer's products. The are top notch and will give you many years of service.

[roger]

I second what Ray has told you about Geezer's products. The are top notch and will give you many years of service.

I didn't know if my regulator was bad or not and didn't wont to spend a lot of money if that wasn't my problem. so now I can get a good one. thanks