I have not installed the Acewell yet but plan on it soon. I do have a problem very similar and this weekend going to try to sort it out.
First thing to do is check the battery - they can charge up and show 12+ volts particularly the AGM batteries - but check it under load - after you charge it try to start the bike and watch the voltage - if it drops too low you may have a compromised cell. Once started check the voltage to make sure you are getting enough out of the alternater / Regulator to charge the battery. If not Snowbum's site has a very good method of determining what in the charging system has decided to become flakey. I checked the batt charged it and saw good voltage and good charging and it failed while driving down the road - all of a sudden. Have one arriving today - then plan to go through everything to make sure the battery failure was not caused by something else. I doubt the Acewell/generator light caused the problem.
Check out Snowbum's site - http://bmwmotorcycletech.info/techni...icles-list.htm