1. Dismiss Notice
  2. Hey Facebook people... We've created a group for XS650.com members to connect. Check it out!
    Dismiss Notice

Help: diagnosing overcharging.

Discussion in 'The Garage' started by DESTROYASAUR, Aug 6, 2017.

  1. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

  2. pamcopete

    pamcopete Ride.Enjoy.Life is Simple

    The regulator senses the voltage on the brown wire from the ignition switch, not the battery voltage, but the output from the rectifier goes directly to the battery, so if there is excessive drop across the ignition switch, the difference will show up at the battery as a high voltage. Even in a well maintained electrical system, there will always be a slightly higher voltage on the battery leading to a short battery life (sound familiar?) I fixed this anomaly on all my bikes with a relay that connects the regulator directly to the battery so the regulator regulates the battery voltage instead of the brown wire load voltage.
    Stardust83 likes this.

    DESTROYASAUR XS650 Enthusiast

    Hey guys, sorry for the late response. Things got busy real quick when the week days roled around.

    I opted for the combined reg/rec unit from TC Bros. Not that the home made one didn't appeal to me, just that I wanted simple and more importantly reliable. I got enough troubleshooting to do on other issue without adding home made circuitry to it. Should be getting here on Friday. I'll let you guys know If that solves the problem. Until then gotta get these Canadian needles working happily.

    I put the the Canadian needles in and now everything is a bit whacked. Happy that I learned that jets, idle mixture, and needle position can all be changed pretty easily with the carbs on the bike. Although having changed all the carb screws to Allen and getting the Topeak bike wrench made a world of diference in working in those tight spaces. I almost don't even have to take the tank off to get the slides out

    Pete, I have recently replaced the key switch and am getting pretty much exact battery voltage on the brown wire. However, anychance you could go a bit more into depth on you're sensing wire to battery mod? That sounds like a not too difficult and very clever/forward thinking modification.

    Looking forward to hearing from you guys!
  4. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    I've had my troubles with aftermarket combined regulator/rectifiers. The last one I bought had a set point of 13.5 volts, this was verified by swapping between two different bikes, it worked and charged the battery, but I wasn't happy with that. I changed to the "home built" units and all is well now on two different bikes. I will never take another chance on any aftermarket reg/rec again. Other's experience seems to be the same, unreliable.

  5. 5twins

    5twins XS650 Guru Top Contributor

    What we're using really isn't "home built", you're not making a circuit board or anything like that. You simply change a few connectors and/or attach wires so the components plug into your harness. The regulators are reliable automotive units. The rectifiers are from the electronics world but a rectifier is a rectifier. As long as you match the specs needed, it should be good. We are discovering some of the really cheap Chinese ones aren't up to snuff but a better one isn't much more. We're talking $4 or $5 as opposed to $10 or $12. Regulators can be had for $10 to $30. So as you can see, there's quite a savings here. I feel those combined motorcycle specific units are like throwing money out the window.
    jussumguy and mrtwowheel like this.

    DESTROYASAUR XS650 Enthusiast

    Alright folks, I'm still stuck.

    I got the new reg/rec in the mail, installed it, started the bike, and of course we're still getting overcharging. You can bet your ass I'm regretting not going for the Napa unit now. Cest la vie. Seems I likely have two good reg/recs now and the problem is obviously elsewhere.

    So, I've gone through and re done some defining checks.

    1: jumping from the sensing wire directly to the positive on the battery and omitting any faulty wiring still leads to overcharging.

    2: Voltage on the brown sensing wire perfectly matches voltage at the battery when the bike is reved. (I used two voltmeters at the same time)

    Those two tests seem pretty indicative to me that the problem is not in the wiring but in the components. Is it wrong to assume that?

    One thing I thing I did notice is: should the brown wire on the regulator have continuity to ground when it isn't plugged into the charging system? To clarify, should the body of the reg/rec be grounded to the frame? Once I've plugged it into the wiring loom and probe the black wire through the back of the connector I have continuity to the frame, but with the reg/rec unplugged there's no continuity to ground at the reg/rec side of the connector. I'm just not sure if that's right of not.

    Anyway folks, I was hoping on riding to the Bay Area this weekend but now it seems I'm still stuck in the valley. I'd love a hand getting the hell out of dodge Let me know what you think. As always, thanks a load guys!

    DESTROYASAUR XS650 Enthusiast

    A note to 5twins and Mrtwowheel: You guys called it. Sorry for taking the easy/expensive route. You've got me feeling like a chump.
  8. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    That brown wire will have continuity to ground because it is also connected to most of your light bulbs on the bike. So, the ohm meter will show a connection to ground because of the filaments in the bulbs.

    AFAIK, that black wire test that you did IS as it should be.

    Last edited: Aug 11, 2017

    DESTROYASAUR XS650 Enthusiast

    Ah sorry, that was a typo. I meant to say the black wire has continuity to frame but when the reg/rec is unplugged the uniy doesn't seem to have any connection to ground. I remembered reading somewhere that these units are supposed to be grounded themselves independent of the black wire. Is that true?
  10. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    I thought that was a typo. The automotive regulators that are mostly used on these bikes need an independent ground wire, not sure about your wiring or reg/rec. This Yamaha still takes some research for me.
  11. 5twins

    5twins XS650 Guru Top Contributor

    As far as I know, most of the combined reg/rec units get their ground through the black wire in the harness plug, no need to ground the unit's case. The automotive type A regulator units usually require the case be grounded.

    DESTROYASAUR XS650 Enthusiast

    Alrighty folks,

    Most recent developments: I've been checking just about everything I can on the bike and in that process I checked my new rotor. That's the rotor I got from mikes that promptly needed the rare earth magnet mod and backed out its screws causing one of the solderes that attaches the slip rings to the winding to crack. I had resoldered it and it had 5 ohms across the slip rings. Now it's saying 0 ohms across the rings (my solders look good)

    So just for curiosities sake I popped in my old rotor that also has 0 ohms across the slip rings, started the bike, and guess what? No overcharging. Extremely poor charging that's about .2volts above just running it with the reg/rec unplugged, but definitely no overcharging.

    So my question is this: does this mean that there was simply something funny going on with my new rotor and another new one should sort me out? Or is there something I'm missing? I feel like usually a bad rotor means no charging instead of over charging. This ones got me a bit stumped. Frankly also a bit frustrated that mikes $150 "new" rotor lasted a solid 70ish miles. Next ones definitely coming from custom rewind.

    What do you guys think?


    DESTROYASAUR XS650 Enthusiast

    There is one diference between the rotors. The new rotor that overcharges not only has 0 ohms between the sliprings but also does not read infinity to ground. It measures zero to ground when on the bike and between 2-3 ohms when tested on the table.

    The old rotor, that doesn't over charge the battery, but only gives about .2 volts, measures 0 ohms between the sliprings but measure infinity to ground both on and off the bike. Could it be that my rotor being grounded is what's fooling my regulator into overcharging?
  14. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Yeah, bad rotors. Not sure about the under charge, over charge difference. Surprising that you found the short to ground. When the short to ground thing starts to happen it is usually intermittent and hard to prove. these are the kind of things that a permanent volt meter can indicate at the beginning of a problem.

    I buy my rotors from a guy who will not sell you the part if you cannot prove to him that the part is bad. We had a hell of an argument over an intermittent short to ground on a rotor. I have won the argument every time.

  15. bwthor

    bwthor XS650 Enthusiast

    Had a year old battery in my truck that had some issue, and the voltage was up over 15V. I didn't think too much about it until it didn't start one day. Charged it up and had a load test done on it and it failed. Got the battery warrantied, and it has been great for two years.

    Might be worth verifying the battery's condition.
  16. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Oh, that rotor with the short to ground......this is happening with the brushes removed or not touching the rotor, right? You can only determine if the short is in the rotor if the brushes aren't touching it. Otherwise the short could be in the wiring to the brushes or the brush holders.

    This is how I won the argument with Pat so he would sell me a new rotor.


    DESTROYASAUR XS650 Enthusiast

    Mrtwowheel, ha! I live for relationships with vendors that work that way. You must have a lot of fun with it.

    Bwthor, I had my battery checked about a month ago and it tested good. But it's probabley taken a good amount of abuse since then so not a bad idea for me to check it again.

    Yea, the short to ground is happening with the brushes disconnected. Aren't the brushes suppose to be grounded themselves though? The brown wire connects to the fuses that go to lights that are grounded.

    What I'm not getting is, how can my bad rotor, that has 0 ohms on the slip rings, even excite enough to create any charging voltage at all...unless somehow having it grounded is flowing extra power through and in turn is charging extra heavily?

    Can anyone confirm that a grounded rotor can cause overcharging?

    At this point I'm leaning towards just getting the full pma and ignition from hughs and hopefully just kissing all future charging troubles goodbye. May be more expensive now but in the longrun it could easily end up being cheaper, it sounds dead reliable, and not to mention I don't really fancy buying a third rotor....that being said if you guys can tell me it's definitely the rotor causing the problem that I could well still go for the cheaper option.
  18. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    You definitely have two bad rotors. Me, I'll stick with the stock charging system and ignition. Don't buy that kool-aid about no more problems. The stock charging system is easy enough to diagnose with an ohm meter and a manual, and not expensive if the tests are done and only the bad components are replaced, and the good components are long lasting. You should have caught the bad rotor sooner by testing it, don't blame the stock system for this. That slap test gets too much exposure here and is not conclusive, I don't see the value of that slap test at all. The rotor and stator are easy to test and the battery can be checked for free, and $40 will get you a new one. There are much better options than those crappy expensive aftermarket reg/recs. I don't see any better options than the stock system with good parts and some low cost mods.


    DESTROYASAUR XS650 Enthusiast

    No ones doubting that my rotors are both conclusvly bad, I'm just trying to find out how I'm the world it's causing overcharging. Seems to me a bad rotor would cause no chargingat all, while this one is doing the opposite. Is it just the bad rotor or is it the bad rotor in conjunction with something else. Because then, even if I get a good rotor, I still have a problem. This last rotor lasted me all of 70 miles, I'm not sure if something else in the bike is causing the rotors to burn out. So, in short, yes, the stock charging system can be good. I have no doubt of that. The issue is that it's not being good to me and after the cost of getting a new rotor again I'll have spent a good bit more than half the cost of the HHB kit. While I'm sure that the stock charging system can work quite well I'm frankly doubtful that it works as well or as reliably as a system using all modern components. The biggest attachment I have to the stock system is that it's theoretically cheaper, so far that is beginning to prove untrue, especially if I buy this new rotor and it inadvertently fries itself again. In conclusion:

    I need to know if a rotor that's grounding out and has no resistance between the slip rings would cause overcharging on an 82 with tci. Once I have that information I can make an educated decision about which path I'll ride down.

    Lastly, I really appreciate all the help Scott! I'm not bashing what you're saying about the stock system at all, it's just that it doesn't seem to be working for me and at this point I really just need it ridable again and not to let me down as often. It's my only vehicle after all. Besides, the engine is super sound mechanically with 170 compression on both sides and pulls like a mule now that the carb is sorted out. It'd just be nice to have a charging system that was equally enthusiastic.

    DESTROYASAUR XS650 Enthusiast

    So, any precident for a grounded rotor with 0 ohms across the sliprings causing overcharging? Has anyone seen anything like that?

Share This Page