Which battery do you have? The rectangle gel cell or something else. I've seen some with a lawnmower or motorcycle battery for their field battery. I have a 12V charger, looks like the charger for your radio gear with different leads. What charger are you using now?

If you have a gel cell it should last you more then one season, I've had mine now for about 5 yrs and it's still going. I use mine to power my starter, glow starter and field charger for my radio gear; haven't went to an electric pump yet.

I usually put mine on the charger for about 12-15 hours before I plan on going flying. I only charge it about once every 2-3 weeks, or something like that. I know I don't charge it every week, but I do at least once a month.

Just like anything else in this hobby, ask 10 people and get 12 answers.