[Al Skierkiewicz]

Joel,
The sealed batteries we use are probably the best choice for our particular use. There are so many variables (users, temperature, mounting orientation and cost) that this battery fulfills most of the needs except weight. BUT... the weight restrictions on the competition are the same for everyone and really help adult advisors teach real world problem solving. The chargers are simple and if someone were to attach a a different charger, the results are not as nearly catastrophic as a lithium ion or nickle hydride under the same circumstances. The internal resistance of the battery has some saving grace in our competition since it will self limit how far you can discharge the battery. i.e. never being able to take it down to 1 volt per cell or less since the controller will not function that low. If you look at the life chart vs. discharged terminal voltage you will see a distinct relation between deep discharge and shortened life.
As to alternative power sources, silver cells would be a better choice for our use. They combine high current capacity, long life, and are slightly smaller and lighter than SLAs. They can be fast charged and used in any orientation. The down side is they are really expensive. $123/ampHour vs. $2.90/ampHour with the SLA.
Al
BTW My son is a ranger at Philmont this summer. (Alumni of Wildstang '96-'98)