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Battery died - help interpreting voltage test results

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Battery died - help interpreting voltage test results

PostAuthor: nichon16 » Sat Jun 27, 2020 7:10 pm

Man I don't feel lucky nowadays, when I bought this bike it ran perfectly and in the last couple weeks a bunch of small issues came up. Al least it's good learning.

Here's my situation if anyone can share their experience.

-Yesterday morning when I turned the key all the lights turned on as usual, then I hit the starter and it did not even crank, just heard a click and everything died, including the lights that would not come back up, it's as if there was really no power left at all.
-I hooked the battery to my battery tender and after just a couple hours it said it was fully charged, I tried to turn on the engine again same thing happened.
-Another couple hours on the tender and after that it worked well, cranked the engine and no issues.

I don't know how old the battery is I just know that it is not from 2019 or 2020 so it's at least 18 months old.
I went to the store, got a multimeter and the following results:

-12.51V with key OFF on battery terminals
-Around 11.96V with the key ON but engine not started
-Did not drop below 11.5V when starting the engine (unless the reading came too quickly and the voltmeter missed it).
-With engine idling it stayed around 13.95V.
-The weird thing is when I gave it throttle it was not going up, in fact it would even go down a bit from 13.95V to 13.85V for example @ 2500 RPM.
-There was no parasitic draw with the key OFF (it showed 0 amps).

I took the bike for a 20 minute ride and everything still works fine, now I'm wondering if I should change the battery, maybe it's just old and it's the reason for all of this. However I'm also worried about the part I put in bold above, that even when reving up the engine it would not get the voltage at the battery any higher. Does anyone think that would point to a Regulator issue?

I'm almost ruling out stator issues since the voltage does go up when I turn on the engine, and I also don't think it was a kill switch, sidestand switch, or starter problem since all my lights were out as well it's not just that it would not turn the engine.

It's raining at the moment but I could do the Regulator and stator contuinity testing tomorrow (as per Clymer manual page 147). But would still like to see if someone has any idea what might be wrong.

The only things I have changed on the bike that I suppose could have an impact is the tail light swap for an LED as well as rear blinkers (not LED but 10W bulbs instead of 27W). I also checked all the connections around the battery, the RR, those added rear lights, as well as the fuses today, did not find an issue.

Thanks again in advance for the help people!
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Re: Battery died - help interpreting voltage test results

PostAuthor: Flyingdog » Sun Jun 28, 2020 1:36 am

nichon16 wrote:[b]-The weird thing is when I gave it throttle it was not going up, in fact it would even go down a bit from 13.95V to 13.85V for example @ 2500 RPM.


IMO: Even though you stated the volts "go up" when you start the bike, but "do not" go up when increasing to 2500+ rpm, I'd point to an iffy stator, atm. When you said you've checked the connections, are you also talk'n about the RR to Stator connection? As in: have you separated it and take'n a look? Those things have been known to melt slightly, exposing, sometimes, just "one" bare wire. Why lotta people just clip that connection and hard wire the two together. Or even possibly, one of the stators' windings (within the stator itself) and/or main wire coming from the stator, thru the case-to-the-RR, could have broke or insulation worn thru. A lesser happening, the RR is grounding to the frame, thru the mounting bolts. Loosing this ground can cause interruption of the juice flow, that the RR is suppose to let thru from the stator to the battery. You can think of this thing as a fancy switch. Don't for get to check the red wire/connection between the RR to the battery. Lotta heat/vibrations going on down around all that stuff. Just some thoughts. Electrical interruptions are hair-pull'n/creative word events..at best.
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Re: Battery died - help interpreting voltage test results

PostAuthor: nichon16 » Sun Jun 28, 2020 7:37 pm

Thanks for your input Flyingdog, I did more tests today so here's what came up I think I may have found the problem.

-I did the resistance test for the alternator, everything checked out well, got around 0.7 ohm for each wire compared to the other ones.
-I opened up and cleaned with electrical cleaner the RR to alternator connector, everything looked fine. Same for the red wire on the RR.
-The test that FAILED however was the RR resistance test, when testing the white cables to both the red and black from the RR I never saw any resistance (and I tried inverting the positive and negative from my mulimeter just to be sure). According to the manual half of the measures should have an infinite resistance, and the other half none
-When I put the multimeter in diode mode however the tests worked I was getting good values when testing the white wires to ground an red (diode test I got from youtube not from the Clymer manual).

But how would that result in the whole system dying when trying to start, and then work fine after recharging the battery, I have no idea... For all I know then it might have been defective since I purchased the bike, and just recently showed some issues.

Does anyone know if something could get damaged if I keep on driving the bike for short distances while waiting on a new regulator I will order to arrive?

I'm pretty much decided on trying a different regulator unless another good point is brought up that I have not thought of.

Thanks.
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Re: Battery died - help interpreting voltage test results

PostAuthor: nichon16 » Sun Jun 28, 2020 10:07 pm

Hmm I'm doubting my own statement already after talking to someone in town who is quite knowledgeable on motorcycles he thinks since I'm getting 13.9V when engine is running that it's not the RR (he didn't care much for my result of the Clymer test lol - since I don't really understand it either it's hard to challenge on that).

He suggested I keep a voltmeter on me at all times and if it happens again to check the battery voltage, that could rule out a dead battery and then it would probably be some kind of connection or wire short.

I'm not the biggest fan of the 'wait to see if it happens again approach' since I could be left stranded somewhere, but at the same time I'm not too knowledgeable on the subject and don't want to spend all my days looking for an issue that may have been a one-time hard-to-explain occurrence.
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Re: Battery died - help interpreting voltage test results

PostAuthor: mark75 » Sun Jun 28, 2020 11:07 pm

JMO: couldn't hurt to re-establish clean, shiny, tight grounds / connections (reg/rec, battery, TCI, key switch, main fuse, etc.)

I would also closely inspect the battery cables for internal corrosion
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Re: Battery died - help interpreting voltage test results

PostAuthor: chrismalm » Mon Jun 29, 2020 2:09 am

:yup:
I'm betting old battery and/or bad cable connections.

Edit: Dang, I did it again. Wrong Gen. Please disregard.
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Re: Battery died - help interpreting voltage test results

PostAuthor: nichon16 » Mon Jun 29, 2020 4:22 pm

Thanks guys, I will take an hour and go through and clean all the connections I can reach without tearing the whole bike apart.

Does anyone have an opinion however on my RR never showing any resistance from the white cables to the red and black?
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Re: Battery died - help interpreting voltage test results

PostAuthor: Flyingdog » Wed Jul 01, 2020 5:32 am

I'm somewhat at a loss bout it being "98'/750". Either way, pretty sure anything in the Gen II series, did away with the side-mounted battery box. Meaning: should already be grounded to the engine.
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Re: Battery died - help interpreting voltage test results

PostAuthor: nichon16 » Wed Jul 01, 2020 11:30 pm

Yes I know it is strange but it actually is a 98 XV750 according to my registration papers and owners manual, I am in Canada so I think they were only sold here, but really when I look for parts or info I just treat is as a 97 XV750.

And about the resistance test, everything worked fine when I had my multimeter in diode mode, but the resistance test for which I never read any resistance is the one with the picture attached from page 151 of the Clymer, don't know if anyone ever did that one successfully?

I rode the bike a good 100km since my battery dying issue first happened, everything good so far but I'm keeping a voltmeter on me at all time so I can be prepared to take readings if it happens again, I did not find any sketchy connections on the bike so don't feel that I have 'fixed' whatever the issue is or may have been.

Thanks again for the input everyone.
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Re: Battery died - help interpreting voltage test results

PostAuthor: Flyingdog » Thu Jul 02, 2020 1:19 am

nichon16 wrote:-When I put the multimeter in diode mode however the tests worked I was getting good values when testing the white wires to ground an red (diode test I got from youtube not from the Clymer manual).


Don't mean to add to the confusion of this thread, but I'm not sure why you used the diode mode of yer multimeter to test the R/R. Way I understand the diode mode is it actually induces a voltage (super low/something like less than .5v) thru the cathode side of the test leads for testing diode functions in a circuit board or whatever. Not of any use when testing R/R or Stator resistance. Least that's how I interpret those gadgets. Lotta functions I never paid much attention too. Might just have to learn more about em. :;:
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Re: Battery died - help interpreting voltage test results

PostAuthor: nichon16 » Thu Jul 02, 2020 3:23 pm

Hey Flyingdog, the diode test is one I got off research around the internet, more specifically this video that explains it well: https://www.youtube.com/watch?v=-2jWIkhy1fo&t=341s

The test in the Clymer does indeed only require to test resistance, but that's the one that did not work for me.
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Re: Battery died - help interpreting voltage test results

PostAuthor: Flyingdog » Fri Jul 03, 2020 10:33 am

Yes, I understand what you're doing. But also be aware there are some R/Rs that have "extra" doohickies in there (like Yamaha) that prevent a person from reverse forward bias testing R/R diodes. Meaning: one way forward bias reading will read normal, but reversing, "as testing has ya do", the current stops (or give ya some odd reading) cause of these extra diodes within the R/R circuitry that just can't be measured from the outside. Probly why Yamaha doesn't include diode testing in their manuals. Hope your results show whatcha need.
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Re: Battery died - help interpreting voltage test results

PostAuthor: pipwild » Mon Jul 06, 2020 5:25 am

Had a very similar problem with my 81, new battery. Wouldn’t start the bike and would trickle charge , show full and still wouldn’t turn the motor over, Checked the voltage and very low again . Ended up being a bad cell in the battery. Bought a new one problem solved.
To test for a phantom draw off the battery, take the negative off the battery and connect the multimeter from that to the negative post on the battery. If it’s drawing you can see from the voltage drop.

Phil

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