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Battery issues - need some help.

Discussion in 'Technical and Troubleshooting Torque' started by davway, Mar 5, 2011.

  1. So i have recently purchased the bike in question - 1996 Yamaha XJR400 and within the first week, the battery went flat.
    Pulled the battery to charge it only to find it had blown up into a balloon.
    Figured it had lost charge for this very reason and went and bought a new battery.
    So here we are, nearly 2 weeks later and the new battery is flat.
    The kicker is i had just done a 100km round ride, left the bike for a couple of hours and when i went to start it again, it was flat - nothing had been left on.
    Had a couple of turns in it but that was that.

    Gave the bike a push start, went for a ride (~20kms), and the battery easily had enough charge to start the warm engine again.
    I thought i might pull the battery and stick it on charge but the battery itself was bloody hot - i wouldnt have thought this to be normal??

    So, what would be the problem?

  2. The bulging of the old battery suggests a build up of hydrogen (in which case consider yourself lucky it didn't burst). Excess hydrogen is caused by excessive voltage, which will also cause a battery to get hot and not charge properly.

    Sounds like the voltage rectifier in the bike is rooted. Get yourself a multimeter and if you can get it started again check the voltage at the battery. It should be reading somewhere between 12 and 14 volts.
  3. Sounds like a faulty reg/rec. What voltage do you have at the battery terminals with the engine revving to around 5K?

    EDIT: Snap!
  4. Ill have to get a multimeter (which means ill have to figure out how to use it i guess).
    No idea what voltage the battery is putting out.
  5. A digital multimeter should only set you back around $10 bucks or so and is a worthwhile investment (try Dick Smith, Jaycar or any auto store).

    Simply set it to 20V DC and connect the two wires to the battery terminals.
  6. I would say.................exactly what the others have said. Sounds like the reg/rec is overcharging the battery.
  7. +1 Overcharging from the description. I would add to JD's comments you want to measure the voltage across the battery with the engine reving not idling.
  8. Thanks - ill check it out in the morning.
    Would there be some reference chart (or similar) that would tell you what reg/rec is the same as another model bike?
    Or, would anyone know what else a SH64OD-12 would be found on?
  9. Just so i can get a good picture of what im doing in the morning:

    If the reg/reg is fine: @ 5000rpm i should get what reading?

    If the reg/rec is buggered: @ 5000rpm i should get?

    If i unplug the reg/rec what would i expect to see?

    Sorry if these are basic silly questions, but electrics really arent my thing.
    Just want to be sure that it is buggered before i buy another one.
  10. You should be getting 13 - 14 volts or thereabouts for a good charge voltage when reving. The swollen battery suggest you are overcharging so you will probably be getting 17 volts plus.

    If you unplug the regulator then the battery voltage will fall to standard load voltage 11 - 12volts.
  11. No doubts it's reg/rec. They are a simple bike, with simple electrics.
  12. Definitely rec/reg.

    Trust me, I've owned Suzukis :D.
  13. Got a multimeter this morning and this is what i came back with.
    Bare battery: 13.84v - not enough to start the bike - killed battery?
    @ 5000rpm with reg - 13.10v but then spiked to +18v so i shut it down.
    @ 5000rpm without reg - 11.34v

    Safe to say the reg is cactus.
    Thanks heaps for the help, hopefully this is the last problem for a while.
  14. Thought i might make an update.
    Found and ordered the only reg/rec i could find in Australia, on Sunday, and had it arrive this morning.
    Had to push start the bike as the battery didnt have enough juice in it.
    Took the battery back to get it checked out, told them what happened (instead of B.S'ing and trying to claim warranty) and they tested it with their equipment.
    1 battery fully toasted, so i had to buy another one.
    So, new reg, new battery and all is good.
    Doesnt run past 13.8v even at 5000rpm, so hopefully its straight sailing from here on out.

    Thanks again for the help.
  15. Good to hear.
  16. Could be worse. Duff rec/regs have also been known to take the alternator with them, which ups the bill considerably.