You can "re-charge" the silica gel packs by putting them in the oven. This site says heat at 250 F for 5 hours. :)
Comment on the 26650 Batteries:
I've created a waterproof battery pack with recharge capability. It's cheap and simple. There are two possible designs (with balancing vs. w/o balancing wires).
A. W/o Balancing
- Put three batteries end to end in the heat shrink. Shrink it down then trim.
- Put a blob of solder paste (low temperature melt & 5x stronger hold than 60/20 solder)
- on each end of the battery pack
- solder on a nickel tab and bend over to act like a spring
- GE Silicone II Caulk: Seal the ends (leaving the tabs out) with silicone.
B. W Balancing
- See above, except add a battery tab in-between the each battery contact
- Add wires to the tabs
- Run wires out to (-) end. These are balancing wires.