Spare battery case

grabcad

This rugged case for 18650 Li-ion batteries is ideal for the use in harsh environments like sand, mud and water* (also saltwater for shorter periods of time).Due to its sturdy aluminium case it can even withstand being run over by larger vehicles.* waterproof up to 60m (196ft) for 24 hours. It might handle even greater depths, but I wasn't able to find deeper waters to test it. :/