It looks a bit 'home made' but it could look better with some more work... Water would still get into that though... It would leak between the bar and the tape slowly...
as I said, it' the very very first prototype. And of course you're right that water would leak inbetween the bar and the tape. But since the button itself is sandwiched between two layers of tape, the electrical contacts shouldn't get wet at all.
Oh well... Water does not conduct electricity, it is the impurities in it that do so water does not conduct a massive amount..
H2O doesn't conduct, but I like to think I'm getting some vital salts when I'm drinking out of the tap, and the salt ions dissociated in the water should conduct pretty well?
Anyways, I just submerged the entire switch in water and it still displayed infinite resistance (as opposed to some M[ch937] when in contact with water), so I declare it watertight :
I will tweak the optics a bit, though.
Eneloop batteries would be brill because they wouldn't loose charge when you aren't using it (unlike normal ni-mh batteries) and they could be charged with the dynamo..
The AAA ones have a capacity of 800mAh, AA deliver 2000mAh.
And actually, Im thinking of using the batteries as the main source of power, and the dynamo as a backup. I haven't really made too many calculations about the power consumption, that will commence when I know what component's I'll be using exactly.
But will Eneloops like the -10C? The Sparkfun Li Battery seems to be rated for down to -25C, but surely it's not the best thing to do to it?