voltage issue

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Same problem here...

My bike: 2009 XB12Scg.

Bike is charging at idle, but cuts charging at 2500@ and higher. But only sometimes, not always but over time, more often than not, causing battery to discharge.

I have checked all grounds, including the weak one behind the triple tree. All fine.
I have checked all wires and connections. And they're all in good condition (I cleaned all connectors too - they're like new).
I have measured the AC voltage with multimeter, and it shows 30V at idle, and climbs to 72V at 4000@.
I have measured the resistance between stator output pins to 6 ohms, and tested NO connection between each output pin and ground.
I have measured unloaded battery voltage to 12,6V, and 12,2V with ignition turned on (engine off).

With these tests done, I concluded that my voltage regulator must be faulty, although working at low AC input (30V AC), when idling.


Kind regards
Sebastian
 
It is probably bad VR. But also check continuity between the VR plug and battery terminals to make sure the wires and the fuse are OK.
 
Last edited:
Same problem here...

My bike: 2009 XB12Scg.

Bike is charging at idle, but cuts charging at 2500@ and higher. But only sometimes, not always but over time, more often than not, causing battery to discharge.

I have checked all grounds, including the weak one behind the triple tree. All fine.
I have checked all wires and connections. And they're all in good condition (I cleaned all connectors too - they're like new).
I have measured the AC voltage with multimeter, and it shows 30V at idle, and climbs to 72V at 4000@.
I have measured the resistance between stator output pins to 6 ohms, and tested NO connection between each output pin and ground.
I have measured unloaded battery voltage to 12,6V, and 12,2V with ignition turned on (engine off).

With these tests done, I concluded that my voltage regulator must be faulty, although working at low AC input (30V AC), when idling.


Kind regards
Sebastian

sebastian: outstanding info and trouble-shooting on your part. your stator AC voltage is a bit high at 4000rpm but better to have that reading than a substantially lower number. in all likelihood your voltage regulator(VR) is faulty. the 2008-2010 VR is a single phase and the wiring harness plugs different than 2007 and earlier models.
correct part # is Y0302.5A8 lists for approx. $129 as memory serves. several thousand still in the dealer system.
also when installing new VR try and ship it out a bit from the mounting bracket to lessen its exposure to header/exhaust port heat. AND replace the battery fuse in the fuse box.
 
Thank you...

I now feel confident that a new VR will solve my issue.

Why would I want to change/replace the battery fuse? You mean re-install it after taking it out for safety, not replacing it with a new one right?
 
Basically their cheapness is the only reason to change the fuse, because of following the logic that they are corroded or dirty, the fuse slot can be corroded or dirty too, so you have to change the fuse slot too.
 
Super, I’ll do that...

Thanks again ����

always my pleasure. if you remove the batt fuse and find that the ends look lightly corroded also check the 2 female spades that the fuse plugs into. if questionable just spray a little kano kroil or pb blaster onto them...work the fuse in and out several times...clean the fuse tips...and install.
 
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