On the road - inconsistent voltage, help diagnosing please!

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by jconly, Aug 8, 2012.

  1. jconly

    jconly Been here awhile

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    BRIEF SUMMARY:
    The bike should be sitting around 14 --> 14.3 V at all times while running, correct? And what is the resistance range for the coils of the generator. Manual says 1 OHM max, but what is the min value?


    And the full story:

    So, turns out I'm getting some REALLY erratic charging behavior, and I'm suspecting this is not normal.
    This is the first ride I've done with a voltmeter mounted, but it just doesn't seem right.

    Currently at a friends garage for a few days, and have begun doing some testing with the multimeter, but have some questions for you on specs, where the manual fails to give the info.

    First off, a diagnosis. It all started when I probably made a major mess up and accidentally shorted the two wires on the starter relay pre-trip. During the ride, my voltage was all over the place, but basically it breaks down like this:

    With the battery at a full charge, IE: 12.7 V, and I key on, voltage comes down to about 12.2 V.
    I start her up, and it comes to around 13V.
    If I let it idle, with only the low beam and my GPS and voltmeter powered on, it will OCCASIONALLY come to 14V, and sit there.
    Any application of throttle drops my voltage down to anywhere between 13.1 V --> 13.4 V. If I roll off the throttle, it will occasionally climb back to 14V but will NEVER see more.
    If the fan comes on at idle, voltage immediately drops down to 12.7 V.

    Being on the road, I haven't had the heart to let it sit like this and see if the voltage continues to drop as the battery drains. I've always either turned the bike off to cool, or taken off down the road to push the voltage back to the 13.1-->13.4 range.

    So first things first, I needed to confirm my findings with an accurate meter.
    Yep, at 5000 RPM's, the reading at battery is only 13.35V, not the 14-15 the manual states it should.
    All connections looked good, so on to the generator.

    None of the three coils are grounded to the engine case, so that's good.
    Next the resistance test.. well here's my main question for you:

    What is the lowest acceptable resistance one should find between generator coils?

    I've been following this flowchart found HERE, keeping in mind its generic, and cross-referencing every figure with what I could find in the manual. Interestingly enough, the manual only states a max resistance of 1 OHM, whereas the generic chart states a grange of .5 --> 2 OHMs.
    All of my coils are returning a value of .2 --> .3 OHM. Is this normal?
    Other than this, the generator passes the AC output test, with all 3 readings across coils outputting around 62 VAC. (Based off of the chart, stating I should be looking for even #'s > 50 VAC. No actual figure for this in the manual that I could find.)

    I'm about to move onto the RR now, and do some tests on the diodes, but before I do, I wanted to make sure that my generator is in fact still good. Seems that way, but just wanted to confirm my resistance was in spec.

    Right now, it's looking more and more like I toasted the RR when I crossed those two wires (twice actually.)
    Does this seem possible?
    One last question for you gurus... are my voltage figures accurate at 13.1 - 13.4 V while riding, or should this baby be putting out a solid 14 --> 14.3 V at all times, like every other bike I've owned?




    Thanks!!!! Your prompt help is so greatly appreciated! Hopefully this little issue will help teach some others about our charging systems as well, since I couldn't find any solid figures via search.
    #1
  2. jconly

    jconly Been here awhile

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    UPDATE:

    Well now I am truly puzzled.
    I was "hoping" to find a bad diode in the RR. Turns out they're all good... Top and Bottom diodes all check out in both directions.

    So could it really be the RR?
    If I'm correct, checking the diodes is the equivalent of checking the Rectifier part, so perhaps it's the Regulator part that has gone bad? In my googling last night, I think I read somewhere that it was possible to test this portion, but apparently it's pretty complex, so no directions were available.

    Anyone know how, or should I just spring for a new Rick's Motorsport RR now hoping this will solve my problems.
    I think at this point, all that is left to do is to check relays and the other diodes on the bike, but I'm not so sure they pertain to my issues?? Seems like they mainly control the start / kill functions of the bike. No problems there.



    Any thoughts before I drop $150 + overnight shipping in 1.5 hours??
    Does anyone out there have the info on the min OHM of the generator coils, or the expected VAC at a specific RPM? Can't believe KTM doesn't have this info listed.




    Thanks!!!!!!
    #2
  3. GZERO

    GZERO Fixing stuff around

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    i don't see things that bad, altough i can see that battery is not that good, what is teh voltage on the batery when cranking the engine? i bet is somewhere around 10 volts
    #3
  4. jconly

    jconly Been here awhile

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    Just tried to give it a turn over after it sitting for at least 30 mins.
    Resting voltage 12.7 V (75% charge?), Lowest voltage 9.5V, and highest voltage after letting it sit for a few minutes, and then reving up to 8K, only 13.7V.

    Yes, the battery probably took a major hit in its life when I shorted the two wires.. it was brand new before that, a month and a half out of the box, with only about 2 weeks worth of use and a life on the tender.

    Perhaps a new battery would solve some of the starting issues I had, and yes, it does seem that it is getting a full charge from the system (maintaing its 12.7V) but what about these inconsistent voltage readings while riding. This is what really concerns me. A system the drops to 12.7V when the fan runs?? Doesn't seem right. At all.
    #4
  5. GZERO

    GZERO Fixing stuff around

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    what starting issues?
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  6. jconly

    jconly Been here awhile

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    Sorry, I guess I should have mentioned this.
    A couple times on my trip it didn't quite have the juice to start.

    First one was out of nowhere. Was riding along on the interstate just fine.
    Stopped for gas, bike wouldn't start. Rolled it away from the pump. Tried again, and it started. Went to ride it, gave it some throttle, and it died off, threw a FI light etc. Basically too low of a voltage it seemed to me at the time.

    Let it rest again, paid careful attention to let the ECU finish it's startup cycle before hitting the button. It started and off I went. During this rest period I did some tests, and the battery was registering in fine at that 12.7 V.


    Later in the day I got brave again and went to tackle some trails. Fell over, did my thing. But basically the bike was warm and fan got some use. Got to the end of the trail, but there was a good bit of start / stop along the route. Turned off the bike at the end to rest. Tried to start again after a careful wait period of ECU boot. No bueno. Turned off bike, waited again, tried again and it started fine.


    Hmmm, maybe I should check those starter relays after all....



    EDIT: After letting the bike run for a bit to test how low the battery would drop during start, I just walked back out and looked at the meter, looks like it is sitting at 13.03 V right now.
    #6
  7. jconly

    jconly Been here awhile

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    Well, now I'm a little more confused than before.

    Bolted everything back together and took the bike for a little spin.

    Seems to be sitting at 14.1V now @ idle.
    Same issue under throttle, voltage drops, but only to around 13.4V minimum this time.

    Heres where it gets new.
    At idle, when the fan comes on, voltage will only drop now to 13.7V (as opposed to 12.7V)... but ONLY if the brake lever is pulled. If I release, the fan will now run, and bike will idle fine at 14.1V.


    So what on earth is going on here?
    #7
  8. GZERO

    GZERO Fixing stuff around

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    What accessories do you have on your bike? list them
    two fans?
    it's a 990 so it always have the lights running, correct?
    What brand of battery and model do you have there?
    Any charger at hand? (if so, what amps does it puts out?
    (do you have whatsapp messenger or Blackberry messenger? so i can help you out chating)
    #8
  9. jconly

    jconly Been here awhile

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    Just the one fan.
    Actually, with that most recent test ride, the headlight was pulled.
    It's a DEKA battery, AGM in standard size.
    I do have a charger here, it's a Die Hard charger... says automatic with a switch for low main or maint-free batteries and it can output 2A, 10A, and 50A

    As far as accessories... I have an Eastern Beaver PC-8 fuseblock connected to the positive post near the starter relay. It's got 2 pos lines that run off, unswitched 20A, switched 30A. Connected to this, not much. 10A Unswitched SAE connector (unconnected). 5A GPS mount switched, and 2A voltmeter switched.

    Downloading the WhatsApp messenger right now. Will shoot you a PM with my username once I get it setup.
    Thanks so much!
    #9
  10. Alleycatdad

    Alleycatdad Unbunch yer panties!

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  11. jconly

    jconly Been here awhile

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    Thanks, that's what I linked to in my initial post though... had been following that.

    GZERO helped me out a bit by phone, and made me realize just how crucial battery life is on these newer FI bikes.
    Took a close look at the battery tonight, and it turns out its a Deka ETX9 (A Yusa YTX9-BS Equiv.) nowhere close to the stock YTZ14S.

    Maybe I'm off here, as in the "Alternative Battery" thread, I notice some people are running a Batteries Plus equivalent to this ETX9... but I suspect that this battery is just too underpowered.

    Think I'll be heading out tomorrow to grab a new battery. The question then, which one. Do I drop the $180 on the stock Yusa, or go the LiFePo route? Or do the cheap $90 Batteries Plus equiv. Choices.. choices.

    Hope this solves the problem though.
    #11
  12. SS in Vzla.

    SS in Vzla. Totally Normal? I'm not!

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    DO check your VR.
    I once had the "starting issues" you describe and automatically assumed it was a bad battery (cheap Chinese sealed battery than came with the bike from the P.O). I bought a new battery to replace it but it turned out that Chinese battery I took out was not being charged properly, but was still good and gave me about one more year of service (I found this later).
    At the moment, I installed a brand new Yuasa and it lasted two days because the VR was bad and fried the battery. The voltage readings I got fluctuated a lot, so it was not easy to diagnose... it would sometimes behave normally (for an extended period of time), it would sometimes go around 11.7v (which is the reason for the Chinese battery not being charged and thus not being able to start the bike on some occasions)... and then, sadly, the voltage went above 16v which happened when I installed the expensive Yuasa (voltage reading which I realized only after the battery was already damaged).
    #12
  13. jconly

    jconly Been here awhile

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    Thanks, I did actually give that a go though. Tested the diodes, and they all came back alright. No problems.
    Havent found any info on how to test the regulator portion yet though.
    #13
  14. GoNOW

    GoNOW Long timer

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    I don't see a problem with your charging system.

    At idle, the bikes stator (and your AC test confirm it's working fine) is not putting out a lot of power. Also, the fan and lights use a lot of power. So seeing 12.7 at idle with the fan on would not worry me. I am guessing you just started the bike and let it idle to warm up. In this case, it's had very little time to bring up the battery to a fuel charge. If you road the bike around for 10 minutes, then you would see a higher voltage and the fan turning on would make less of an impact.

    And as long as the charging system gets into the mid 13V at cruising speed, then I would also not worry. 14V is nice, but can overcharge a battery if it stays at that voltage for too long. But AGM batteries like a higher voltage.

    The best way to charge any led acid battery is to bring it up to 14.2V at the recommended charge rate of. Then float them at 13.5V. So ones the regulator sees 14 or so volts, it may kick down into float mode and drop the voltage down.

    The rectifier/regulator on a motorcycle has a lot to do and can control very little. It can't control the amount of power coming from the stator like in a car alternator. At idle, the amount of power coming from the stator may be just over the amount needed to run the bike, leaving little for battery charging. But at 5,000 RPM, the stator is making way too much power and the regulator has to burn it up as heat.
    As fast as the 9x0 revs, the regulator can have a tough time keeping up. But it does not really have to as batteries are very forgiving of voltage/amps spikes.

    I have a volt meter on my 950 and the voltage has always been all over the place, but it's in the 13V range when cruising and that is all that really matters. I got 6 years out of the stock battery. But I do keep it on a trickle charger when I leave it parked for more then a week.
    #14
  15. jconly

    jconly Been here awhile

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    I wish this was the case, but unfortunately, with the fan on I see 12.7 while riding too. Interstate speeds none the less, and this isn't just after turning the bike on and letting it come to idle. This is after a few hours of riding too.


    Something I neglected to mention, over the course of my trip my 5K cruising voltage seemed to drop. It went from that comfortable 13.4, down to only 13V.. As I got very close to my destination, my ABS warning light came on showing it was no longer active. This happened a few times, each time I stopped... turned the bike off to let the system reset and restarted. Seems to me that the ECU was starting to shut things off from too low of power.

    Thanks, this is incredibly helpful to hear! That's one thing I have not gotten any feedback on, is a frame of reference for a standard. When cruising though, it it moving around, because mine will not jump, it simply decreases voltage as RPM's increase. There is a definite correlation between the two. And it seems backwards to me.
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  16. GoNOW

    GoNOW Long timer

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    With the new info, it sure sounds to me like you have a problem.

    I would bypass the fan switch and force the fan on and turn anything else on to create as much of an load as possible. Then hold the engine at 4,000 RPM or so to simulate running down the road. Then check for voltage drop across all the connectors dealing with the charging system. Also check battery voltage with a DVOM and compare with your meter.

    Also check AC voltage on each leg of the stator (especially if you start seeing the low voltage problem). It does not happen often, but a shorted stator can be just fine at idle, but voltage will drop at higher RPMs and/or when it's hot. Check both with no load (regulator unplugged) and under load.

    Most of the time when a 3 phase stator starts to die, only a single phase goes, so if you compare the 3 and see one that has lower voltage, then you found your problem.

    I am placing more bets on a bad connection. That brown connection is known for having problems.
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  17. jconly

    jconly Been here awhile

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    So, with a full load, fan running and all... voltage at the battery reads 14.1V now. When I bring it up to speed, I still get the drop to around 13.5V or so. This feels a little bit better. Not sure what changed to be honest. Cleaned some connectors.


    So anyway, I figured I'd check voltage coming straight from the VR as well under these circumstances. Left the ground on the battery, and took the + reading right from where the + DC connects from the VR to the wiring harness. I'm getting a reading of 14.25 --> 14.3 V there. Hmmm. Resistance in the system just nocking down the V @ the battery?



    Checked this yesterday as I mentioned. Everything came back equal and fine, around 65VAC on each leg, around 5000 RPM. Seems normal.


    I hope you're right, but I sure as hell cant find it. I've disconnected and cleaned almost everything, with the exception of some of those really hard to get to ground spots on the engine. Unfortunately, that means the battery ground.

    I did pick up a 11.2 AH battery this morning to test ,to see if this makes a difference.... But when I took measurements of the 8AH that was installed in the bike this morning, it was sitting happily at 12.95V. Had it tested at Batteries Plus when I got the new one, and it was testing somewhere around 230 CCA (Rated 180). Used it to start the bike to do these tests just now, and the lowest drop it saw was down to 10V. Better than the 9 yesterday.. :huh


    Well, I guess I'll try the larger battery now to see what happens.
    Will also let the bike run for a good while too to test the stator again once it's up to temperature.
    #17
  18. jconly

    jconly Been here awhile

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    Ok, so enough is enough...

    I finally went ahead and bolted everything together and took her for a real ride for some real world testing... AKA let the components really heat up vs this 15min at a time thing in the garage.


    So, here's what I found... everything is basically the same as it was before!
    All connectors cleaned, WD-40'd, etc... with the proper sized battery in.

    But, paying a little closer attention than my previous rides, I did seem to learn something. Here's the breakdown:

    At the beginning of my ride...
    13.1 - 13.4 V @ throttle.
    Roll off, and things would gradually climb back to 14V
    If fan would hit, @ Idle, voltage would sit at 14V, @ throttle it would sit at 13.1 - 13.4V based on RPM. (This is different than my initial ride here, so I guess cleaned connections did help)


    But, when things started to heat up, inconsistency set in...
    @ Idle, things wouldn't always climb to 14V. Sometimes it would stay in the 13.1 - 13.4V range. Under power, I would still get these figures, but it was not a consistent DECLINE (read: voltage has always dropped as RPM increased) as it was before. It was all over the place. When the fan would hit, voltage would drop to 12.8V, wether @ idle or under power. And, I took it one step further this time, I let the bike sit @ idle with the fan on. 12.8V lasted for a while, but eventually started to flick to 12.7V. This lead me to believe it was draining my batter (which I've been very careful to keep charged @ max.)


    And some other things I have learned from testing and more thorough searching..

    Voltage directly from the stator would read 14.2V - 14.3V @ idle during garage tests. But 14.0V @ the battery (or the positive post and engine ground.) Theres definitely some resistance in the system, and from looking at the wiring diagrams, I am surprised that direct VR output snakes through such a complex system before finally making its way back to the battery.

    One other thing I learned from from following the wiring diagram for the 07-08 990 EFI starter diagram... I don't have any continuity to the switched ACC circuit @ the fusebox, from the VR on either + cable. Everything else was fine... maybe I tested something wrong?

    [​IMG]



    And finally, I also managed to find one other post on here where someone had stated the output from the Stator should read around 75VAC on all three phases. Problem is, no output RPM was mentioned. I'll take this to mean that my consistent 65VAC @ 5K RPM across all three phases means my Stator is good. Especially with no grounding found.



    So, what's next??
    Well I'm throwing my old battery back in for the trip home.
    Figure if I'm going to kill one of them, it might as well be the smaller 8AH one, especially since it's seen some stress.

    I'm also going to be ordering up a new VR. This is the only thing left that I feel could possibly be wrong. Torn right now between Rick's Mosfet, or a Shindegen Mosfet. Right now I'm leaning towards the Shindegen route, and replacing all my connectors with it... assuming it bolts up fine. The Stator to VR connector will definitely be replaced. Haven't yet decided if I'l going to earth the VR in the same place, and connect the positive to the same position either. If I don't connect both + & - from VR direct to battery, I'll definitely be updating the existing connector to the harness with something sealed as well.

    Will keep this thread updated, in hopes this will help someone else out.
    #18
  19. AdvGa

    AdvGa Long timer

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  20. bomose

    bomose Long timer

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    I have been having the same problem. Everything checked out OK. I cleaned all the connections and it seemed to to be fine. I started to crank it the other night and it seemed like a weak battery. Then it just started clicking.Load tested the battery and it was good. Took the connections back apart including grounds.Seems good now.I'll be interested to hear your prognosis because I'm leaving for Colorado next Thursday. So hurry up and check it out!:D
    #20