battery not charging

[cliffsbitz]

hi all , hope someone can help , had fazer for last 6 months with no fault, however last month the battery went flat, so as not knowing when it was last replaced i put a new one on. hey presto (i thought), a few days later , guess what sluggish starting. so i have a contact at yamaha, who told me that rectifier was very common , so £130 later i still have same fault. now I'm in the motor trade , but worked on cars for last 25 years , so i thought id check a bit further with the help of a multi meter  , haynes manual & you tube. have checked stator outputs on 3 phases , I'm getting around 20v ac on all 3 at idle rising to around 65-70v at 5000 rpm. have checked resistance on all 3 and getting about0.6 ohm. & nice checked any dead shorts to earth, which there are not. finally I've checked earths ,
only ad ons i have are heater grips ( which I've disconnected ) plus wiring mod to utilise 2nd head lamp, but even disconnected that.
also forgot to mention that with meter on battery @5000 rpm it struggled to get 12.8 volts. and at idle 12v


thanks hope that makes sense
 

[yourebarred]

That ain't right.
Out of interest what does it idle at?

[chaz]

I don't know much about electrics but the voltage you are getting seems a bit low, I thought fully charged should be upto 13.2 volts (2.2 v per cell x 6) and when reving the engine around 14v. Is it possible the new battery is duff? Is the starter motor OK? do the headlights get brighter when you rev the engine? You could try jump leads to see if the starter motor spins faster? have you checked to see how much power is being used with the ignition off, you can see how on youtube, not much help sorry.

[cliffsbitz]

Thanks for replys, at idle about 12v , once I fully charge battery, is fine for a few days


Thanks

[BBROWN1664]

From your tests it sounds like the charging circuits are OK and with a new battery that should be good too. Sounds like you have a bad connection somewhere between the two.

[bigralphie]

sounds  like you stator is breaking down to me 

[yourebarred]

What rpm at idle?

[ukdiceman]

Have you solved this problem?