If the bike isn't charging correctly, how many miles?

[thepaintbox]

If the bike isn't charging correctly, how many miles would I get before all was lost?

I'm inclined to think it's an issue with this new battery (6 weeks old, started farting a week ago) because the bike seems to start better if it's been running for a while. I imagine a bike that isn't charging well would have the opposite issue. If she sits overnight I'm inclined to say a brief prayer before hitting the little button.

No noticeable change in performance once she's going.

Sorry if I'm poking a dead horse.