Might be the ignition switch needs to be taken apart and cleaned. Sometimes making contact and other times not. There is a post in here somewhere on how to do that.

 

I ran into a very similar problem years ago (and I do mean years ago) on my 82 AMF Wide glide while stationed in Germany. Took off on a cross country (Germany to England via ferry). I would stop and the darn thing would be dead. Took the seat off, and it started right up. Took off again and after 30 to 50 miles it would die. This went on for the whole trip.
Finally a real good friend and hell of a Wrench (as most Helicopter mechanics are) found the issue.
It seemed that my seat was rubbing against a small wire just near the frame and shorting out making the resettable fuse trip.
Bottom line, is I would suggest a short someplace.

 

Voltage on a battery only shows potential, a battery right off a charger has a surface charge which is a false high reading. Load testing a battery is the true test. I keep my bikes on a battery tender when not riding. The problem I have is keeping a bike for more that 2 years.

 

I have found that when car and bike batteries are on a tender or a battery charger and are 100% charged show around 13.50 volts its not a great difference when yours is around 12.95 for a length of time on a tender but is shows signs that the battery maybe on its way out.

I keep both my bikes on a tender as I had starting issues if my 14 fat boy was left for more then a week..

Good luck...

 

You are reading the float charge if you see 13.5 volts. Unplug the charger and turn on the ignition with a few accessories for a few minutes, then read the voltage. It might be as high as 12.9 but will not be 13.5 ever.
I have 3 battery tenders working right now, I checked the float charge on all of them. 13.10,13.18 and 13.15. Lead acid batteries can float at 13.6 and some Agm's like a bit less or around 13.4 depends on the maker. The problem with too high of a float charge is that you will boil out the electrolyte over time, the voltages I am seeing are safe. All of my chargers are HD of various models.

 

Letting a battery sit on a bench for 12-24 hours can allow that surface charge to dissipate.using a multimeters the voltage on an older battery that measures 12.57 volts may be fully-charged, while a brand-new may measure 12.92 volts. Both are considered acceptable. it just depends how you wish to test a given battery...

 

Bluraven you got it right. Turned out to be the ignition switch, not the battery. I put up another post asking about ignition switch replacement vs repair.

 

Were the cables tight when you took the battery out? That kind of thing happened to me when one of the cables loosened off. Had Reaper quit on me while riding down the highway at 75 mph, all electrical was gone, then fire back up. Did it a couple of times. I pulled over took the seat off, and found the ground cable just loose enough to lose contact now and then.I had to actually touch the cable to feel that it was loose.

Cheers!

 

Glad you found the culprit.

 

Post #10 in this thread has a link to ignition switch disassembly and cleaning.