I'll fit some optimate leads to my race bike and get it on the genny when I stop - simple really.

I did the same with mine but if you are doing 4-6 races on one race day it doesnt charge up quick enough, and somtimes you may get back to back races then you really are screwed!
you will need to carry a spare bat, but each to there own.. im putting my flywheel and charging back in afer a couple of nightmares in the paddock, thumbing around changing batteries over in 10 mins, pluss sometimes if you need to put wets on aswell theres just not enough time....