| Author | Message | ||
     Tempest766 |
Hey gang. A few weeks ago I started getting the low voltage indicator code from my 2008 XT. The check engine light would usually go out after riding a bit, so as is typical, I ignored it hoping it would go away. Eventually the battery would no longer turn over the engine and read about 11.46 volts. I then removed and charged the battery and it's holding at about 13.15 volts with no load on it after a full overnight recharge. I'm hoping it wasn't damaged by too much discharge. Enter the diagnosis of the charging system... I removed the air scoop and did a quick stator and voltage regulator check. There is very minimal resistance between the two leads going to the stator (0.5 ohms), and no short to ground across either one. I would have thought with the coils the internal resistance should be a bit higher, but I dunno. Next I did a polarity check on the voltage regulator and it does not pass current at all, in either direction between the battery side and the stator side. Used the diode setting on the multimeter. Bad regulator, right? A couple of questions: 1) did I achieve due diligence in diagnosing this and coming up with the bad regulator as the culprit? 2) what is the typical OEM replacement cost and availability for the regulator? 3) is there a drop-in replacement that is as good or better, in terms of quality and/or price? 4) is there an easy tap-in point to check the stator output at different RPM ranges once I replace the regulator? Just through the connector to the regulator? Comments? | ||
| Electraglider_1997 |
Check your regulators diodes as shown in the video on this link. http://www.roadstercycle.com/Roadstercycle.com%20V ideos.htm There are videos showing how to check the stator also. In both cases you need a multimeter but the tests are easily done. I replaced the regulators with Mosfet regulators this year on my 06 and son's 07 ULY. Turned out that both bikes regulators had bad diodes. The 07 had all 6 diodes gone bad and my 06 had 3 bad diodes. Stators in both bikes tested fine ....thankfully. I've replaced the regulator on my son's 07' and on my 06' with the Mosfet and they work great. (Message edited by electraglider_1997 on August 18, 2014) | ||
| Froggy |
Likely is the voltage regulator has failed. A new one is $121 at American Sport Bike. http://americansportbike.com/newdir/Item/17507 There are aftermarket options, but nothing that is plug and play, all will require some kind of splicing connections and figuring out how to mount it. OEM one works good and can be installed quickly and easily. Before buying though, do more testing, and confirm the stator output is still good (follow the directions in the electrical manual). | ||
| Tempest766 |
I don't have the electrical manual. I can possibly check voltage output at different RPM ranges once I install a new working regulator and figure out how to get the multimeter to tap between the regulator and stator. ... Praying that the stator is not bad ... Yeah, $121.75 was the price at the HD dealership too, with a current backorder. When I do get a new regulator I will probably do something to increase the effectiveness of the heat sink. Thanks! | ||
| Reepicheep |
Resistance sounds OK on stator, but another easy test is to start the bike with the 77 connector disconnected, and measure AC volts between each pin and ground (stator side). You should see from 10 to 60 volts (that is from memory, so check manual) on each wire. You need an AC volt meter for this, and most affordable ones won't read accurately at different frequencies, but they will do good enough for this test. The primary cover "sniff test" can be informative as well. Pop off the inspection cover and take a whiff. Shorted windings burn, and burnt windings and transmission oil stinks like nothing else. It's easy to cause a cascade failure by having a bad stator or battery, then jumping the bike from a running car. The car has a much stronger alternator than the bike, and the bike has a shunt regulator that tries to regulate power by dumping it through the regulator to ground. The shunt regulator is sized for the bike stator, the car alternator can just fry it. (DAMHIK). | ||
| Tempest766 |
I did jump start the bike from a truck last year, but I was aware of the alternator current overload so I did it while the truck engine was not running. | ||
| Reepicheep |
That should be fine then. That's way below the voltage the VR is shunting at. | ||
| Griffmeister |
No need to "tap" into the wiring. Disconnect the stator plug and measure AC volts from the stator with the engine running. Output is a function of rpm, 20-28 VAC per 1000 rpm. The manual says to test at 2000 rpm so you should see 40-56 VAC at that speed. If those readings are consistent then make sure the terminals are clean and plug everything back in. You can measure DC voltage right off the battery if you want a rough idea of the regulator output but you need a controlled load to do a proper test. At any rate, keep in mind that the rated output of the charging system is 30 amps and up to this point the regulator should be able to maintain 13-15 VDC. Note that the actual load test is done at 3000 rpm so you may see lower voltage at idle. | ||
| Tempest766 |
Just didn't want to run the bike solely off of the battery while testing the stator, but I guess what Griff suggested will work since the test is only 30ish seconds long, if that. Now I guess I need to bite the bullet and order the new regulator. It's the same price through HD and through American Sport Bike. Wish there was a less expensive supplier. | ||
| Tempest766 |
Something else just occurred to me. In the weeks prior to the regulator going bad I'd every once in a while notice a bright headlight flash. Didn't burn the bulb out but while cruising on back roads after dark sometimes the low beam light would quickly flash brighter. I initially thought it was just a bump in the road that made the beam appear to bounce but in hindsight it would seem that the headlight was getting too much juice from a regulator that was in the process of failing. I seriously hope those spikes didn't cause any other electrical damage to the bike. I've replaced one headlight bulb in 23,000 miles and this was well before all the battery/regulator problems. ... and still praying that the stator isn't bad as well ... | ||
| Electraglider_1997 |
Tempest, All you need to do to verify the stator condition is to identify and pop open your stator connector which is the 4 prong #47 connector. You will also need to open the 77 connector to utilize those to very heavy gauge wires for the multimeter test of the stator and (R/R). The stator is 3 phase and uses only 3 of the prongs in the connector with the 4th being rubber plugged. When you pull the connector apart, one side goes to the stator to do stator checks and the other side goes directly to the regulator/rectifier (R/R) to allow you to do the R/R diode checks. Do the grounds check and the resistance checks for the stator and do the diodes checks for the R/R just like the video shows as I suggested in my other post above. If you'd do this then you'd know by now whether the stator is shot or not. I did not know how to check the stator or regulator until I watched these videos and then checked my regulator and stator. Easy-Peasy. The smell test as suggested might be a good indicator of a bad stator but checking for resistance and grounds proves it. Don't buy anything unless you know the part is bad and that is done by checking with your multimeter. Anybody can do it once you watch Jack's videos on the Roadstercycle web site. He shows you how to do these things that the Buell service manual writes about. Seeing how it is done is way easier than just reading about it. (Message edited by electraglider_1997 on August 19, 2014) | ||
| Tempest766 |
re: electraglide... Understood...except your information is for the bikes up through 07. The 08 XT and later have a single phase stator with only two wires, not three...which smells to me like cheapness on the part of Buell towards the end of their run. Voltage regulator passes absolutely no current in either direction between the battery and stator connectors. It's bad and must be replaced. The question then becomes why it went bad in the first place. Just overheating, or voltage surges that it could not handle? I'd expect a shorted stator to put out less juice rather than too much so I'm leaning toward overheating one too many times. Will check stator voltage output once I replace the regulator. Thanks for your input though. | ||
| Froggy |
That is the only proper way to test its output. With a healthy battery, they bikes can run for quite a while without the stator, some racers run their bikes without one to reduce rotating mass. Disconnect the headlamp to buy you some more time if needed (don't pull the lights fuse, safety interlock won't let you start)
Another sign that your VR is failing.
Unlikely, the headlight bulb is the weakest link, it will blow before the rest of the electronics do.
It likely is fine, but it is good practice to check it when diagnosing anything charging related. Regarding Electraglider_1997's advice, it is correct but not accurate for your bike, the connectors are two prong and the system uses single phase instead of 3. | ||
| Froggy |
Voltage regulators simply wear out and fail eventually. No different than basically any other part getting old and wearing out. | ||
| Tempest766 |
Thanks Froggy. We're on the same page regarding this and where to go from here. Did you attend the WV Buell campout last weekend? I thought I saw a post where somebody tagged you in a photo. I wanted so much to ride down since I live in Pittsburgh but with the bike running the battery dead it's a good thing I didn't attempt it. | ||
| Froggy |
I missed this years, been stuck dealing with moving so unfortunately I couldn't get away for the weekend. Honestly if you posted this a little sooner and needed a loaner VR, I would have gladly sent you mine. Hell, that offer still stands, but American Sport Bike likely has it in stock and can get it to you quicker than I can. | ||
| Electraglider_1997 |
According to Roadcycle.com you can use a 3 phase Mosfet R/R for a single phase stator by using just one of the stator wires from the R/R. That would imply that the 08' ULY R/R can be checked just the same as the older model's 3 phase R/R, but only 1/3rd the checks. Anybody know if this is true? | ||
| Froggy |
That is correct | ||
| Tempest766 |
Thanks for the offer on the VR, Froggy. I went ahead and ordered it from the HD dealer. Should be in middle of next week. Was a little cheaper than American Sport Bike on the left coast and then paying for shipping. Downside is that I'm not on two wheels for at least a week.  | ||
| Tempest766 |
Regarding loaner parts, what I really need is a drop in ECU to see just how badly my stock replacement one from HD is detuned. All I know is that when I bought the bike it was torquey as hell and had all kinds of power. HD replaced the ECU and flashed it with the 09 firmware and it's been a dog ever since ...smooth, but a smooth dog nonetheless. | ||
| Tempest766 |
New VR installed, stator puts out proper juice that is dependent upon RPMs, and battery is all charged. Bike runs well now. Weird thing happened when installing the new VR though. Got a couple of sparks while screwing it to the frame before hooking up the wiring...and the battery wasn't even in the bike. Does the VR contain any semiconductors that store charge, and that could have been holding charge prior to installation? I did a quick diode check with the meter before installation but it is weird that I'd get sparks without the battery being installed at all. | ||
| Natexlh1000 |
Semiconductors do not store charge. Capacitors store a charge. Sometimes, a large cap will develop a charge over time by itself. This is quite dangerous if you pick one up. Usually, you wrap a wire around the terminals of a large cap you intend on storing. |
