Testing The Charging System

Step 1. First things first, load test the battery. Most places like Auto Zone will do it for free. Even if it measures over 12.5 vdc it can still be bad under a load. Battery is typically rated at 19 amp hours and 270 Cold Cranking Amps (CCA).

Start the engine and measure DC Volts across the battery terminals, the regulator should be putting out 14.3 - 14.7 vdc at 3600 rpm and 75 degrees F.


Step 2. 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.

To do this with a meter which is more accurate: black lead to battery ground, red lead to each pin on the plug, start with the voltage scale higher than 12vdc and move voltage scale down in steps for each pin. Any voltage is a bad regulator.
You may get battery voltage on all three pins on the newer 3 phase regulators.
The no voltage is for older type regulators with diode indicating the diode is bad and the regulator needs replacing.


Step 3. On the other part of the disconnected regulator plug. Set the multimeter for Ohms x1 scale and measure for resistance across the pins of the stator. You should read something around 0.1 to 0.2 ohms for the TC88 32 amp system.


Step 4. Then check for continuity between each pin on the plug and frame/engine ground. The meter needle should not move (infinite resistance)(digitals will show infinite resistance) if the meter needle does move (indicating continuity)(digitals will show some resistance), recheck very carefully. If the meter still shows continuity to ground the stator is shorted (bad).


Step 5. Set the meter to read A/C volts higher than 30 volts (the scale setting for voltage should always be higher than the highest voltage you expect or you may fry the meter). Start the bike, and measure from one pin to the other on the plug (DO NOT cross the multimeter probes! - touch them to each other). You should read roughly 16-20 vac per 1,000 rpm.


Step 6. If the battery was good under load test, if the stator is NOT shorted to ground, and the stator is putting out A/C voltage, then the regulator is bad (most likely even if if passed step 2).


Generally the following is true:
Check your owners/service manual for the system amp output for your bike.
22 amp system produces about 19-26 vac per 1,000 rpm, stator resistance is about 0.2 to 0.4 ohms.
32 amp system produces about 16-20 vac per 1,000 rpm, stator resistance is about 0.1 to 0.2 ohms.
45 amp system produces about 19-26 vac per 1,000 rpm, stator resistance is about 0.1 to 0.2 ohms.

 

Re: *Testing The Charging System

Dear Mr. Data,

thanks for such valuable help.

However with your post you raised a doubt in my mind.

In Step 2 you are writing about connecting a test light to the negative terminal of the battery to touch each pin of the regulator after that. My negative terminal of the battery goes to the frame and I don't think it will allow a test light to shine no matter where I will connect it to, except to the positive terminal of the battery. Is there somehting I don't understand ?

With my (edited) little multimeter I can't measure the stator to have anything else than no resistance. Infinite resistance between any of the two stator terminals and the frame.

I can't do the test with the running motor because it's late here and my kids are sleeping. The thing which already happened to me on another bike was that the connection regulator - stator was bad. The connectors don't really inspire me much confidence. Is there any way to check that ?

Thanks a million
Fatboy92
The regulator

 

Fatboy92

Yes there is, by connecting to the negative battery post (ie. ground) you are checking for voltage at the regulator plug pins doing this. It sounds a bit backwards but it is in fact correct. If there is voltage at the pins, it usually indicates a bad bridge rectifier in the regulator. The diodes in the regulator will allow current flow ONLY in one direction when operating correctly and if you detect current with the above process, it indicates the diodes are bad in the regulator.

 

Well thanks Mr. Data, I have learned a lot by reading your tip.

My problem is however solved. AS I wasn't so sure about my understanding of the subject, I went to see my mecanic and he found it in two. The plug !!!! The regulator plug to the stator was not plugged in correctly. I had checked it, but it turns out that the rubber part sticking out under the cylinder has grown. Goodness knows how HD can install such rubber (rubbish). Now the plug doesn't fit any more. The bike is 15 years old and the plug just won't fit !!! I find thisa little irritating.

Anyway. My problem being solved I'll stick around your forum, because I find a lot of nice people seem to post.

Had I been a little closer we could have rode together, but who knows one day.



Holger

 

Glad you found the problem in any event. The older evo's had this problem, you are not the first to experience it. There is a clip on the market that will keep the plug connected and will not allow it to disconnect from vibrations, you may want to look into that.

http://www.jpcycles.com/groups.aspx...a239&DID=1047e9e6-5126-464d-a9a1-c0a73e8765a9

 

Mr. Data, i am not familiar with this system. Other than the previous findings, i checked for vac from stator. And i believe i have a 3 phase system... i have a square plug with three pins. 06 model. i have as follows 16volts on top left and bottom left pins, 16 volts on top left and bottom right, 1.3 volts on bottom left and bottom right. this is all at idle and all values raise when i accelerate except for the last. So i think i have a bad stator and bad voltage regulator.. Im a little disgusted, this bike has only 20,000 miles and was bought in feb. 06... I wonder if hd will help out. I have no problems replacing this myself, i am a auto mechanic and have a bike lift at work, but it would be nice to get it covered under a goodwill warranty.Anyway does my findings seem accurate.

 

Many thanks Mr. Data and the rest of you who have tested and responded to charging system issues. I am seeing something that I wanted to run by everyone. According to the tests on my 1997 Road King, the voltage reg is toast as I am seeing voltage across each PIN when testing to ground. Then on the stator, everything tests out good until the VAC output tests. I get 3, regardless of how fast the motor is running, I get 3? Also, yes I changed primary fuilds recently and they did stink bad, not the typical stink of that fuild but I don't recall if it was a burnt spell. Its heading to the dealer tomorrow and I am assuming it will need stator and voltage reg. Just wanted to throw that out to see if anyone has had this type of result in the past.

 

I tested my 2004 ultra after a it quit charging this weekend. I had 11.5 volts at the regulator on both pins and only 16 VAC on the stator, so I'm getting ready to replace both. The Regulator was replaced last year at Sturgis about 20K miles ago. Is this a common problem with both going bad at the same time? About 20 miles before it quit charging, I accidently hit the kill switch while I was riding so I just turned it back to run without stopping. I wonder now if that maybe caused a surge or something. Also, I usually turn the bike off with the master switch rather than the kill switch. My friend says to always shut it down with the kill switch. Could this have caused my problem? I have learned more about my bike since I've started reading all the posts. Thanks for such a great learning tool.

 

Usually when replacing one component, it's smart to do both the regulator and stator and use matched parts that were designed to work with each other. Using the ignition switch to shut down is fine.
These parts operate very hot because of the design and if you have an excess of lights and electrical equipment on the bike, it causes even more of a load/heat which can shorten the life of the components. The biggest mistake made is in reassembling the rotor and some use an impact wrench which can jar the magnets loose and lead to early failure.
There's always the problem of the harness coming from the regulator that has been known to ground out where it crosses over the frame mount and should be relocated to prevent this from happening.

 

Thanks Mr. Data for the quick reply.