I fully agree with what catman had to offer. Just for what its worth, I change out my batteries at 24 months (period). They are getting tired.!!!!!!! You probably have noticed no real probs on those calm days and half what you expect and need on the windy days. I know its a hastle and everyone would like to eek out that last month. Face it, its a new season and believe me you don't want the hastle. Don't ruin a good trip in the future because you took a gamble. They only have so many recharges.