It is his daily driver and he does 300ks per week so it will not be the parasitic drain from the GPS mount. (0.02amps)
Lasting 3 months is a puzzle ?
Does it go flat when riding or parked ?
I would fit a volt meter and keep a close eye on the readings you get.
Some of the 19 rides in my shed
2014 V2, Snoopy
2009 Wee, Pumbaa the pig
WR450F, The Blue Postie Bike
YZ250N smoker with rego, Stinky.
Yamaha MT09 (FZ09), The Scud missile.
Club Lead not Club Med.
He with the most toys wins.
Out of my depth in a puddle.
Live life on the edge you will see more that way.
Ridding a motorcycle keeps things in balance.
At the end of each trail and at the end of each day history is made.