Charging Issues

Took my 82 XJ650 out today. Ran fine for about 6 miles,then it started sputtering more, and more til it died. Of course Im thinking gas, carbs, etc... but come to find out battery is dead. It looks like the bike isnt charging. So.. I checked my alternator brushes, they are fine, all grounds, wires look fine. Where/how should I start chekcing. I searched and read some posts but it wasn't enough.

Im guessing it is the alternator, but Im not sure how to go about diagnosing anything with it. Any ideas?

The bike will run as long as the battery is charged, but as soon as it goes dead thats it. Which tells me the alternator isnt recharging the battery.

Thanks

 

Take your battery to NAPA, AutoZone etc and have it load tested. This is the easiest place to start and also a likely failure point.

 

A battery loses 1% of its charge each day. it can take about 2 1/2 months of non charging to make it fail even if its charged.


I ran my bike 2 hours a week during the winter and put on a trickle charge for about 4 hours before taking it out last weekend. this will be the 2nd year on this battery.

 

when you say the brushes look fine Did you measure them there is a spec and a wear line on them. I believe the spec is 10mm but I am unsure if that is from the line or the line is suppose to be 10mm I am sure someone with mor eknowledge will chime in.

 

Bobby check the voltage at the battery when reving over 2000 RPM. Should be 14.5V or so. If not you have an issue with the generator. Could be the rectifier or a wiring prob or the stator.

Having your battery load tested is a good idea - it may have issues. But the above will tell you if the Generator is working.

 

Also, check all those plastic connectors. They are known trouble spots and can melt if not making a good contact. And that can lead to stator/regulator getting ruined.

 

I checked it with a volt meter. Its about 12.8 when revving. The wiring looks fine. Checking closer tomorrow but seems sturdy.

Is there a a way to test the rectifier? Im gonna have the battery load tested tomorrow. But charged it tonite and it runs and cranks fine. What are some of the things that can go wrong with the alternator?

I saw the wear marsk on the brushes. They have plenty of meat left. Its no where near the marks.

 

Ok, heres the latest any advice is appreciated.

Trickled charged the battery all night. Tests at 12.01 volts when not running.

When running the the current at the battery is 11.08 to 11.5. Doesnt change when revving.

I tested the 3 white wires coming from the alternator and each are giving out 5 volts. So that means the alternator is charging.. right? Is that the correct voltage?

I tested the red wire coming out of the rectifier which is the hot wire and it is putting out 11.08 volts also.

I am pretty sure that it is the rectifier since 15 or so volts are going into it and only 11.08 are coming out.

Do you guys agree? Is there any other way to test the rectifier?

 

I got some bad news for you Flat,
Your battery seems flat (no pun intended), what temperatures are you experiencing right now?
Nominal charging voltage (not current) for the battery is 14.5 +/- 0.3 volts (14.2-14.8 range). You are not charging at spec and this is indicative of alternator brushes. Check out your brushes (10mm is wear limit), replace as needed and retest.
As for the voltage you see out of the alternator wires, I suspect you are not reading the output correctly as the voltage there would be AC, not DC (this would explain the relatively small number you are seeing). Check with your meter set on AC, you should see about 25 VAC.
I don't think your rectifier is bad as it can only put out and output that is directly proportional to the input (which is low to begin with).
Testing your rectifier/regulator is fairly easy. To test the regulator, connect your meter (on DC volts now) between the black and brown wires with the engine off but ignition on. You should see less than 1.8 volts. Now start it, you should see the voltage rise to between 9-11 volts. You should see 14.2-14.8 between the black and green wire. This should not vary much after you rev up over 2000 rpm and let it return to idle.

 

Thank you very much, Robert. You are correct on the ac coming from the alternator. Took me some research but i did figure that out. Brushes look brand new... Guess i'm off to buy a battery.

I sincerely appreciate everyones input! I always over analyze everything! Will report back when battery is replaced.

 

Turns out it was the regulator. Tyler93 saved my a$$ for the second time. Let me tell ya, anyone buying parts from this kid can rest assured he is trustworthy.

Thanks Tyler. Put the regulator on and am heading to the smokeout rally in the am!