[DonRotolo]

The lifetime of the battery is extremely (almost entirely) dependent upon how you care for them. All other factors (including brand) combined are trivial in comparison.

1. Always keep them fully charged (except during a match, of course).
2. The faster the charge the harder it is on the battery. 2A is an ideal rate, but in competition you may need to charge faster than that.

Where most teams fail is #1, particularly during the summer. As a data point, I have a 38 Ah gel cell battery that still starts my riding lawn tractor despite being over 20 years old. It doesn't have all 38 Ah any more, but by taking excellent care of it, I have managed to keep it going far in excess of expected life.