I've got an Eton Scorpian sitting in my kit. Nothing fancy, but enough rubber armor to ensure it survives getting bounced around. It uses a very low power (3x 2/3AAA)cordless phone battery pack. Building a 3x AA eneloop or other LSD rechargable pack would be a plug and play solution to the low battery capacity.
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Hope for the best and prepare for the worst.
The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane