Before the Scitsu owner sold out a few years ago, I had trouble with both of mine, on my Triumph 750 Sportsman and my Yamaha F500, trouble with the internal batteries
and charging, and he suggested I send them back and he modified them to be powered by an external 9 volt battery
pack. One new battery
every race weekend, no problems with charging internally, worked great. Don't know if the new owners would do this for you though.