Thanks in advance for any help! I picked up a 08 sportster about a year ago from an older gentleman who had broken his hip a while back and was hoping to be able to ride the bike again. He had the bike sitting for a little over 2 years ( bike had 3k on the clock when I bought it), and he would start it up a couple times a month he said. Bike runs awesome, but after putting 1k miles on it the bike is having a charging problem. Intermittently the battery light would come on and off. It has now become a more common issue and the battery gets drained rapidly. Sometimes I can turn the bike off and back on and the light will go away but always comes back on. I’m currently going through the charging system with my meter, checking the battery fresh off of the charger, reads good. When I put it in the bike with my meter on it and no keys in the bike, I can see the voltage dropping ( 12.7 to 12.58 ) in less than a minute. Unhook the connection and it holds steady. It’s bleeding voltage somewhere, but I can’t find it. I have disconnected the grounds and cleaned the terminals, but not sure where to go from here. Doesn’t seem to me to be the stator or regulator because the bike is turned off, but I honestly don’t have a clue. I would appreciate any advice or suggestions! It’s beautiful here in Hawaii, and I’m bummed I can’t ride without getting stranded and pushing it home. TIA!!

 

1. What voltage are you getting on the battery when the motorcycle is running? Should be 14.5 VDC give or take.
2. Find your fuses and unplug them one at a time and read the battery voltage. If you unplug one and the voltage stops bleeding then you have found the circuit causing the issue.
3. Then get a wiring diagram and trace that circuit and find out where the issue is.
4. Sometimes it is the ignition switch causing the issue, you can unplug the wires going to it and see if you still get a voltage drop.
5. A freshly charged battery will bleed down on its own as it eliminates the surface voltage
6. How old is the battery?
7. Have you had it load tested?
8. Check for corrosion behind the fuse panel also.

NOTE:
The above information, while credible, is worth what you paid for it and should not be considered gospel.
Do due diligence, research and have a H-D Field Service Manual before working on your bike.
You will probably have many opinions and suggestions presented; make sure you research the person providing the helpful information as there are some who provide good information that is useful and some who speak out of other orifices with gibberish. You will figure out this quickly.

 

Sorry, I need to read slower lol.

 

Thanks for the reply! I put a new battery in the bike a month after I bought it. I have not had it load tested. I will check the voltage when the bike is running again, I have tested it before but I can’t remember the exact voltage. I originally started looking at the stator and regulator but just saw how much the battery was draining with no key in the ignition and that threw me. I am an electrician by trade but automotive electrical is intimidating. I do like your suggestion to pull fuses until I can see the voltage stop draining. Definitely going to try that and check the voltage while it’s running. I pulled all the fuses and checked them a while back , some had a little corrosion and I cleaned them. Maybe the terminal block could be cleaned as well. Not sure how to go about cleaning it.

 

Here is the link for testing the voltage regulator and stator.

There could be something shorted and causing the voltage bleed (diode or resistor burnt out).

https://www.hdforums.com/forum/elect...sting-1-a.html

https://www.hdforums.com/forum/elect...sting-2-a.html

Disconnect the voltage regulator to the battery, if it is the stator or voltage regulator causing the issue, there should be no voltage bleed when disconnected.

You can also go to Cycle Electric and they have testing information.

http://cycleelectricinc.com/

Good luck!

 

Thanks again for the help! Yesterday I went through the whole process a couple times and everything was checking out. Proper voltage at the battery (fully charged but have not had it load tested, will do that today), proper voltage out of the stator and regulator, and pulled each individual fuse to check for what was bleeding the voltage. Only when I disconnected the stator and regulator did it stop the voltage drop, but during testing and the bike running it all tested correctly. I was pretty frustrated because I just want to feel confident that I have found the problem before I start replacing parts. I decided that I would get it all back together and ride it until the lights came on and check it out that way. Stator checked good (25v ac) , battery was a little low (10.4v dc), and (.112v dc) out of the regulator. So I’m pretty sure that the regulator is the issue. It tested fine yesterday and this morning while sitting at idle but 50yards down the road and the dash lights were on and nothing coming out of it. Turn bike off and back on and the lights are off, take it back down the street and same thing. I’m going to order the regulator today and hopefully it will fix the problem. Thanks for all the advice!

 

If a regulator has a diode that is burnt or shorted it will allow current to feed back instead of checking the one way circuit.

I had a Honda V65 Sabre that gave me fits trying to find the voltage/current bleed. It ended up being one of the diodes in the regulator. It would show charging just fine when running a the other 2 diodes were doing their job.

Connect the regulator to the battery, unplug it from the stator: To check the regulator unplug it from the stator. Take a test light and clip it to the negative terminal of the battery and then touch first one pin and then the other on the plug that goes to the regulator. If you get even the slightest amount of light from the test light the regulator is toast.

Let us know if a new regulator solves the issue.

 

Yeah, I tried testing it with the test light yesterday and I didn’t see any light. Only today I had the thought of testing it after I rode it until the battery light came on. It has been a pain troubleshooting this intermittent issue. Don’t know why I didn’t think about testing it with the dash lights on, probably would have saved some time, but that’s learning! I am just pumped that the stator tested good, was not looking forward to replacing that. I will definitely check back in when I get it installed, just ordered it but may take some time because I live in Hawaii and nothing goes quick.

 

This is what happens when you guess without access to a wiring diagram. The regulator is always connected to the battery via the main fuse even with the ignition turned off.

Wiring diagram here:- 99949-08_en - 2008 Wiring Diagrams (harley-davidson.com)

 

Just wanted to post an update. I got the new regulator installed. And that seems to have been the fix. I took the bike out for a 45 mile ride and no lights came on. Stopped a few times and it fired back up easily. The advice I could give after this whole thing is to make sure that the dash light is on when you test everything. I really appreciate all the replies, ride safe everyone!