Testing the Battery and Charging System (Harley Davidson FXSTC) 

Early this summer my buddy's ride a 92 Evo Ultra was losing headlight power. When we pulled over , the bike barely started but his volt gauge was showing 10V. I always carry way too many tools !! so we did a volt check with my meter same result & no fluctuation from revving motor. We checked all connections from battery positive circuit to ground back to volt reg. & found the issue at plug going into stator pins insert at the motor. I simply used needle nose pliers & crimped the female ends to assure a good contact put a little dielectric grease & pushed back onto stator pins.At this point, the bike needed a push to start but within a couple miles, the gauge had climbed to 12V & eventually climbed & maintained at 13.5V .The trip & all issues have never re-occured since, but after this particular trip, did install a new boot holder a metal clip used to keep boot in place from vibration & losing contact. He never had one & was overlooked since owning the bike a few years . Years earlier on my friend's 72 Shovel a similar problem had occurred, but we traced by shear luck !! The ignition switch brass rotatory plate in the switch housing was creating a break in the charging circuit ! As we were about to give up, I was rocking the switch between on & headlamp on position & the light brightened up. Found a dealer further west on our planned route who coincidentally had ordered one for a customer & was never picked up Go figure ! I changed out the switch right there in the parking lot !Issue solved... The trip must go on !

Excellent video. MY battery was having trouble turning the engine past the compression stroke, yet always pulled through and started. I did these tests and found while cranking the battery dropped to just over 5volts, when the engine was running I was getting 14.30 V. So with your help I was able to determine that my charging system was working and my battery was on its way out. Thanks for the help!

Very cool video. Straight forward and easy to understand, even for a RUB like me.

I use the Pico PC-based scope, an older 4-channel model. Like it alot! Found it very helpful in my day job as an auto tech and figured it would be interesting to use it on the bike. As you can see, it quickly pointed out a bad stator!

Thanks SB, for your video. Now I know where to start.

Appreciate the kind words! On the FXSTC, the stator resistance is very low (less than 1 ohm) and should have no continuity to ground. It is a two-wire stator. Three-wire stators need to be checked between all combinations of leads (A-B, B-C, A-C) and will also show very little resistance if all is well. High readings (mine was 120+ ohms) or a reading of "0" when testing between leads is a sign of a problem. We plan on doing more basic electrical stuff, so stay tuned Ride hard, ride safe!

Thanks for the video. Never let someone wrench on your bike if you can do it yourself...

Glad it worked out for you and you found your problem!

Great video sir, gave me the exact info i was after. Thank you

Great video and I really like the way you respond to the questions. Subbed.

Nice vid but I do have a suggestion... once you've determined you're not getting the 13.5 - 14.5 charging voltage to the battery, the next test I do is simple... with the bike off, unplug the regulator from the stator and simply check both sides of the stator for ground fault. The AC output test is nice but I do the ground fault test first as it's the most common issue with a failed stator. Ride safe everybody.

thank you. you helped me out. that is real cool of you to take your time and do this. if your ever in california look me up dinner on me.. thanks again

Thank! As for your upgrade, if it would be necessary then the install instructions should point that out. But I don't think so. Fuses are to protect circuits from excess current flow, and that current flow is determined by the loads (lights, horns, etc.). Now, if you increase THAT side of the circuit it's a different story. A higher output charging system will just give you more POTENTIAL supply that is only used if needed.

Thanks for the tip / help

Thanks for the help had charging problems with my 2010 Sportster used your tips found have no charge between Stator and battery may be the regulator or Corrosion in the system due to the wonderful british weather - Thanks again

Good stuff!

Hey, go for it! You'll find that you'll see more, and find more faster with the scope.

Hi I have just moves to Richmond and need to find a locally owned shop for my Harley Davidson sportster a 10 point check and the oil changed. Thanks

good video. I am currently changing my system over from 32 amps to 40 amps. Do I need to change any breakers or fuses on this upgrade? Thanks again!

Two questions: 1. What were the basic system test results? (OCV, loaded voltage and charging voltage) 2. What is the AC output from the alternator with the regulator unplugged, measured at the open connection and with the bike running at 2000 rpm?

I know, I was a fighter Comm/Nav troop in a previous life. I miss the test equipment, especially the backshop gear. Which DSO are you using and how do you like it?

Thank you for your help. Sounds like you need to come out west I got a few whiskeys for you in Utah

Thank you

I have a question and I hope somebody to help me. I have a 2007 FLHTC IU that has set and battery is going dead I replace the battery and the bike will not start. when I turn on the ignition the only lights to come on are the speedometer and the tachometer and they constantly Flash. I call the Harley dealer and they have no idea what the problem is. could somebody please help me I miss my mule.

ok i have the same problem i was riding and the bike went dead checked the bat it was dead recharged it it happened again , checked the stator per your video stator tests ok. im lost what do i do?

I am working on a 98 softail with a EV2 engine on it. It won't start. I removed the starter. What a pain. I tested the starter out of the bike. I used a Yamaha XJ 650 battery to test the starter. I hooked jumper cables to the starter and it spun right up. Negative to the negative on battery to the metal on the starter. Postive on the battery to the postive on solenoid. I took a small jumper cable to the relay on the starter to the solenoid and the starter spun up fast and with great torque. Put the starter back on the bike and installed the battery that was in the bike not the XJ650 battery but all I hear is a clicking noise. Like the starter is enguaging but the starter motor isn't spinning up. Why? Battery warehouse said the battery is good.

I liked the DSO readout! Now I have a reas..er, excuse to get one.

So this morning, Sunday of all days, I get on the bike for a nice long ride. The battery is dead. Only has enough juice for the little red blinking light. I just rode the bike two days ago. I am bummed out..... How long is the expected life of a stator, regulator and battery?

I have a haritage 2002 softail it has 3 wires on plug to stater ow do I check that one

Hello, I just got a Sportster 1200 Custom from 2014 about 3 weeks ago. I have got it out about 3 times those week but yesterday I tried to start it and it did not. It is making a noise like "tic tic tic". I checked the battery and it is showing 12,25 when I turn ON the starter the lights and everything seems alright but ir does not start. Is that voltage so low that wont start my engine? Thanks so much

Hi Southern Biker... Really great video.. I have 78 Shovel and when i cahrge up the battery everything looks fine and when i rev up the bike it shows an increase in voltage and thats normal but my problem is that when i ride for more than 30 miles the bike drains the whole battery.. should i change stator and look at it? or is it something else?

can I use this same method to check the system on my 81 shovelhead?

👍🏼👍🏼👍🏼

Good informational, video. Great bike, too, with the reliable, EVO single cam, 1,340cc, engine. Last year of the EVO. Hold on that bike, cause in my opinions, the TWINKIES, produced from 99 to the present are a FATALLY FLAWED DESIGN with PLASTIC tensioners in critical components. No plastic in the engine on this bike, solid metal, GEAR DRIVE ON THE CAM SHAFT AND THE OIL PUMP, unlike, the TWINKIES with two silent chain drives and PLASTIC tensioners, rubbing against a METAL chain. They were designed to have to be periodically inspected and to be replaced when wear on the PLASTIC tensioners, reaches 3/32' of wear and it's an expensive procedure to replace them, especially the inner tensioner inside the cam support plate, which silent chain drive operates the two cam shafts. Also, the EVO had the flywheel assembly, bolted together, with a crank pin bolt and nut, torqued down to hold the flywheel assembly in true. Not with the TWINKIES, as they use a pressed together, flywheel, with nothing holding the two sides of the flywheel assembly in true and they WILL come out of true, rather quickly and eventually crater the engine, and cause CATASTROPHIC ENGINE Failure.It's not unusual though to have to replace components on the HARLEY charging system, over and over again, especially the stator, due to it's bad location, inside the primary drive, and right up against the hottest part of the bike, the lowest part of the crankcase, where it gets all the maximum engine heat and enclosed within the rotor and enclosed within the primary drive cover itself. It cannot dissipate any heat at all. It's a major job to have to disassemble the entire primary chain drive, to even get to the rotor and stator, to change them out. Same thing with the starter, due to it's location directly behind the rear cylinder, and underneath the oil tank. It gets all the engine heat from the hottest, cylinder, the rear cylinder and so it gets heated up a lot, too.So, hold onto to your EVO, as you have the true HARLEY sound of yesterday. Enjoy it.

my NEW battery dies too fast. i fully charge it and it starts right up. i turn it off and try to start it up again and it sounds like a drained out battery.

Could not see how you checked the regulator because your arm was in the way

I replaced the stator and the regulator and the bike still dies