This is maybe the 5th time this has happened,
short story, bike would not start occasionally so i would charge battery then it would start, so i got a trickle charger and have been using. today i rode for 1 1/2 hrs did some walking around headed home stopped after an hour, bike just clicked when trying to start. all lights on and volt gauge showed 12 +, jumped and started right up. got home and started testing after a google search.
1 checked volts at battery w/ high idle, 15 volts.
2 unpluged regulator and checked ohms read 0 ohms
3 started bike and checked regulator plug in and it showed 45 + ac volts under high idle.
NOW what ??!!
had battery tested before bought trickle charger showed battery was fine

 

You don't say what kind of bike or model, but HERE is a thread that might help.

 

**** sorry 2005 electra glide