I've had good luck with the HD stock batteries. When I am not riding, I keep my bikes on a trickle charger and no problems so far. Sometimes my bikes will sit for a month or so because I am out travelling for work and they always start right up.....

 

Make sure all connections are clean and tight. Mine was a 1/2 turn loose and she sputtered on me.. didn't think that could be the problem but it was..