i had the same problem and thought it was the battery. it wasnt because i had to battery check and it was fine. i went throught all my ground wires and other wiring harnesses and i found that there was a big white clip loose under the left fairing that i am assuming connects the battery to the alternator. i clipped it tight and everything is working great

 

Well USUALLY after you have to charge a battery twice or it dies twice it won't hold a charge. Motorcycle batteries are so small that even one or two drains will ruin it. Test it for a draw, use a multimeter on Amps and take off the negative off the battery, with one lead touch the negative cable and the other the battery making a full loop. With the key off and nothing on it shouldn't be more then 0.1 amps. If it is then you have a draw killing your battery when/if it sits.

If everything else is good then yea make sure its charging. I believe the f4i starts charging at 2000rpms if i remember correctly.

Good luck with everything.