RE: Flying with different batteries
Kjell Olav,
I am in the same situation, having collected batteries through several years.
Although expensive, I think this is the only solution to the problem:
Through away all the old packs, including those you bought this year. (Seriously.)
Buy a sufficiently large number of sets of batteries at the beginning of the season and use them approx. equally much through the year. They will deteriorate a bit during the season, but should remain quite equal to eachother.
Repeat treatment annually.
Magne