Alternator failure - behavior?

[MarkT]

Coming back from Inzane, I detoured E to Waynesboro, visited there.  Then NNW through MI to Ludington MI and the steamship ferry to Manitowoc.  WSW to Madison, more visiting; SE to Kenosha, More visiting, SW to Wichita, visit, then WNW to Franktown. Over a week travel time, about 2000 miles.  Over that time I watched the volt readout on my Escort go from about 14.0v to 11.5 on the last day.  At that point the escort was complaining (beeping) about low volts esp with ignition on before starting. I am running a 90/130 headlight daytime always at low power except if need to warn turners (have high-power headlight mod - my version of BonS Smart Switch) and 2 std H4 headlights as spots, always on high beam during daylight (60w). No other high-draw accessories, just the 300w stereo but it draws much less when not cranked up. (Bike is set up with heated gloves/jacket, belly tank pump, GPS, radar, phone charger, trailer with LED lights, and LED running & tailight - all either off or draw very little).  The biggest draw is the tungsten headlights. The bike has 50k miles.  

Since then the volt readout has returned to 13.9v.  After returning I checked the volts of the battery, it was about 12.5 (normal), connected the auto charger and it ran just a little bit then shut off as the battery was charged.

I think my alternator is failing when warmed up.  BTW, there is no cover over it, it's getting plenty of cool air.

Does this sound like it's failing to you?  If yours failed, did it do this?

I am thinking of going to LED headlight and spots to reduce the load.  That's the ONLY reason I would do that, as I am otherwise very happy with the light output I have now - I have a great light soln.  My H4 spots have never failed, while I replaced the 130/90 H4 main headlight bulb for the first time on this trip.  I always carry a couple spares; they typically last 2 years or more.

[Brewer]

Hey Mark,

Do you have an auto part store nearby that can test the charging system? They look at you a little funny until you explain this bike has an alternator not stator but the test tool they use will work on a valk.

It will test the battery, alternator / voltage regulator all together. I know you are in 'the country' but it might get you some additional information to help find the issue.

Regards
Brewer

[gordonv]

My 88' GW GL1500 w/ 60K miles alt failed. It would start up, while running would be low voltage (battery), and within a few minutes while warming, would rise back up to high 13 and 14.1 while driving.

It then took longer and longer, before producing a higher than battery voltage, until after 15 min warming, it would not go higher.

Removed the alt, cleaned out the brushes, back in, and all was well.

Now my 99' IS, is giving me trouble. Unknown when or why, have a volt meter, driving down the road at 14.1v. Stop. Start it up, and it's running at bat voltage for 10-20 min. No problem for the rest of the day.

I'm hoping that its the same trouble. Clean the brushes. At least I have a spare set of brushes, and have just recently help msb on replacing his, so at 105K miles, I'm expecting that is all that is wrong.

[Lyle Laun]

Mark
I had an ebay alternator that did something similar. At low rpms it would put out 13.6v or similar. At highway speeds it would drop down to 13.1v. Bike would start the next day but would drop down in volts at highway speeds. This got progressively worse over a 10 day trip and was down to about 12v but still started every morning.
At home I took the Alternator in to my rebuild guy. He rebuilt it and it's been fine since. I can't remember for sure but I think he said the stator was bad.

Regards
Lyle