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...

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thessel

Many thanks glider 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.

jaceddie

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.

glider

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.

jaceddie

Thanks Glider for the quick reply.

jaceddie

I found the stator burnt as expected. I have another regulator off an 03 ultra that was changed out for chrome when new. I'm retired, so money is an issue. I hooked up a 12VDC power supply to it so I could check it against the old one. It tested the very same! With 12VDC across the leads that go to the battery and ground, it still shows 12VDC on the pins. I know you can't trust a new part to be good, but I know this one worked when it was taken off. So.... I'm wondering if I'm doing something wrong when testing it this way, and is there a chance of burning the new stator if I use the 03 unit? I know it's hard trying to figure out a problem without laying your hands on it, but your thoughts would be appreciated.

FLHTC_91

Hi,
1991 flhtc glide classic;

Regulator looks ok. ohm tests OK. Voltage at battery 14.8vdc OK.
Stator ohm tests also OK.

Multi-meter reads house AC OK, but the stator output is jumping around ~7-15vac, no mater what the rpm is. Is that do to the frequency not being read by the cheap multi-meter or a bad connection due to all the oil?

Also the radio/clock keeps resetting.
The rest of the electrical stuff works great plus battery is keeping good charge.

Oh an additional question, where are the fuses on the 1991 flhtc, I've found very little info on fuse location.

Thanks, It was a great day to ride in Sarasota today.
-Don

glider

Don

Check the harness from the voltage regulator where it passes under the bracket/frame area to see if it is chaffed through on the edge. You may be able to start the bike up and turn off the lights and see sparks as you move the harness.Very common thing to happen on those year bikes. Also suspect the oil from the primary getting through the inside of the wiring in the regulator harness causing a problem. Another common thing. The fuses may be breakers under the speedo in the housing.

From your description of the stator output, it may also be the start of a bad stator.

FLHTC_91

Thanks glider, I'll check it out. I also get a misfire when I turn my lights on.

HarleyRidnWoman©

Oh WOW...this was a BIG help to this ol' electrically-challenged gal! Just got done testin' my bike and sendin' off the info to my wrench. Hopefully we can get things figured out and get the ol' gal chargin' again! GREAT information, THANKYOU!!
HRW

crucey

First let me thank you for taking the time to help with these types of problems. I rode home yesterday from Tulsa (40 miles) and at my last stop my Ultra was acting different. IE, high idle dim clock, volt meter down to the far left. After it wouldn't restart I let it set while we ate and then pulled the seat to see what the battery terminals looked like and when they were ok I hit the starter and it started right up. still a high idle. I turned off all the acc. and the idle settled down for a while. I'm going to test the other stuff from step 2, I'm thinking the battery was strong enough to get me home. I'll post again when I find out what's up. One question though if the reg. is bad or the stator what would it hurt to just replace the one that's bad. And see what happens. I haven't had either go bad before, but I'm assumming their neither one cheap. I'm sure the strain of one being bad on the other could be the deal. I'll do the test's and then price them both. Thanks again.