battery voltage question

6 replies to this topic
  • new2blu

Posted May 30, 2016 - 10:05 AM


I have a bad battery on my 2003 WR450 (10 volts and battery charger will not charge it). I was able to hook up my lawn tractor  battery to the WR with jumper cables and the highest charging voltage with the bike running was 13.30 volts at the battery terminals.  So Yamaha manual says the voltage should be 14.1-14.9volts. I was wondering what voltage someone else was getting with a good battery.....not sure if my voltage regulator is bad also?



      Thanks in advance.

  • bigl

Posted May 30, 2016 - 09:17 PM


What revs are you testing at?  Give a bit of throttle and see if it picks up.  Not all bikes give 13.6V-14.4V at idle.

  • new2blu

Posted May 31, 2016 - 02:24 AM


I gave it some revs (4-5k rpm) and 13.3 is as high as it got.

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  • stevethe

Posted May 31, 2016 - 05:06 AM


Hum running a dead battery and trying to test voltage output? = Results in a useless test.

  • toten

Posted May 31, 2016 - 05:53 AM


I agree that the dead battery could be pulling enough power to make the test ineffective. If you disconnect the dead battery and use lawn tractor battery only it'll be a better test.

  • new2blu

Posted May 31, 2016 - 12:34 PM


Hum running a dead battery and trying to test voltage output? = Results in a useless test.

maybe I didn't explain this wel. The possible bad battery completely removed and substituted with a know good battery and 13.3 is the highest I could get.

  • new2blu

Posted May 31, 2016 - 12:36 PM


What I would like to know is if anyone could check their voltage and post it here.


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