Diagnose this electrical issue?

[stopintime]

Last summer (~10,000 miles ago) I lost a battery. The days before produced uneven running. It's last day it refused to start and was replaced. Happy days the rest of the year. Seemed to be charging ok. Maybe a volt less than usual...

Charged this winter.

This year just a few miles so far. Started at 12.8V. Ten days with +/- 10 daily miles, relatively slow riding (low revs).

Today it started to cough. Then it would not start. Just solenoid clicks. 11.8V. Roll started easily in second gear, but slowly died 10 seconds later. 11.2V. Roll started again, but died after two seconds. Now, not even a click from the solenoid

Got it home. Took the battery inside. Expected it to be quite dead, but measures 11.75V.


I was planning to get it going with a charged/new battery/on a car battery and measure between the yellow wires. I've been told to look for 40-50 V alternating. If yes, the R/R is the suspect.

... just a little surprised that the last minutes of riding didn't empty the battery...

[ducpainter]

At 11.8 volts an AGM battery is considered dead. Your bike wouldn't run, so it couldn't lower the voltage further.

[stopintime]

At 11.8 volts an AGM battery is considered dead. Your bike wouldn't run, so it couldn't lower the voltage further.

It's been dead'er before and brought back to years of life. Just lucky?

[koko64]

 Nate's right. The bike was only running off the battery with no help from the charging system. When the battery is fully charged up again check the voltage at the battery when the bike is running at 3000 rpm, then you'll know. A volt less is a lot (every Volt is precious).

[koko64]

It's been dead'er before and brought back to years of life. Just lucky?

Good battery CPR and probably a quality battery.

[ducpainter]

It's been dead'er before and brought back to years of life. Just lucky?

Bike was likely charging then. Not sure how the battery would get below 12 VDC with a functioning charging system.

[stopintime]

Bike was likely charging then. Not sure how the battery would get below 12 VDC with a functioning charging system.

Oh - out in the cold with an activated alarm. The alarm will draw from the bike's battery to charge it's own back up battery.

I read Capo's charging system thread. He mentioned that city riding, at 3,000 revs, will eventually kill the battery.

I'll do the simple on-the-battery-terminals voltage check. 14 volts on ~4,000 revs?

[ducpainter]

Your bike should be charging at 3K. I've never had an issue, even with my old 2 phase system when running at 3K.

If it were me, I'd just test the stator between the yellow wires. It should climb to 70 vac pretty quickly. If it passes that test, and the maxi fuse is good, just replace the regulator.

[stopintime]

Your bike should be charging at 3K. I've never had an issue, even with my old 2 phase system when running at 3K.

If it were me, I'd just test the stator between the yellow wires. It should climb to 70 vac pretty quickly. If it passes that test, and the maxi fuse is good, just replace the regulator.

It HAS done 220,000 km 

[ducpainter]

That's what I'm saying.

[stopintime]

For the yellow wires test, my meter has a V~ symbol. Is that it? With a choice of 200 and 600.... which do I select?

[Howie]

Select 200.  Before that, check the charging rate at the battery like koko said.  And the connection where the stator wires connect to the regulator.  Common failure, possibly cheap fix. 

[stopintime]

To check the connectors.... running bike, battery terminals before and after connector check/wiggle/fix? Or continuity across?

[Howie]

Sounds like it is bad enough that a visual inspection will show burning  Separate the connector and inspect.

[stopintime]

Sounds like it is bad enough that a visual inspection will show burning  Separate the connector and inspect.

No visual signs. The white connector has been replaced by three bullet connectors long ago.