I have a 2015 RT with 8800 miles on the ODO. It went into service in April 2015 as a dealer demonstrator. I bought it in July 2015. My practice is to keep it plugged into an Optimate-4 unit whenever it's in my garage. This served me well with my 2008 RT, so I figured I'd do the same with the new one.
Three weeks ago I returned from a 2.5-week trip overseas. I unplugged the Optimate and started the bike. All the time I'd owned the bike, it would start with just a single push on the starter button. Since returning from the trip, it always takes two pushes. The starter seems to sound just as strong as it always had, but the engine just doesn't start (when cold) as it had. Once it's warm it starts immediately with one push.
Omega Man and I have been in texting conversation about this. His first suggestion was to crack the throttle a bit on starting. That did not change anything. His next suggestion was to see about battery voltage on starting. Since this RT has a voltage readout, I switched the display to constantly show that number. I found that after turning on the ignition and letting the RT prepare itself to start, the voltage displayed "12.1volts," dropped down to "11.7" then rose back up to "12.1." I then started the engine (two pushes of the button of course), and within 20 seconds the voltage climbed to "14.1volts" where it stayed until the engine was shutdown.
Omega Man suggested that the battery needs a load test to determine its health. I'll look into doing that this week.
I hope that someone who reads this has some wisdom or experience with this situation. Thanks for reading.