Why your outdoorsy friend suddenly has a gummy bear power bank

Why your [ultra-light hiker] friend suddenly has [the world's lightest] power bank.

I remember Colin Fletcher, years ago, writing in The Complete Walker about trimming the borders off his paper maps to save weight, which seemed like an insane over-optimization to me. But then, I'm not an ultralight hiker.

I am impressed folks are getting their loads down to 10 pounds though.

That insane over-optimization is how folks are getting down to (and below) 10 pounds.

I'm not even remotely an ultralight backpacker, but I do count ounces (no matter what your weight limit is, you can't escape making tradeoffs to stay within it). Your hiking load is a great example of how quickly apparently insignificant quantities can add up. Saving fractions of an ounce multiple times gets you large savings far more quickly than you'd think.

I'm down to around 10 lb base load. And then I hike in the desert where I carry 5 - 7 liters of water (11 - 15 lbs). And food. Saving a pound here and there is totally worth it, but there's a large part of the country where prudent hiking means the majority of your weight is water.

If saving here and there is worth it, why would a hiker carry a 300g battery? Imagine the savings from leaving that boat anchor at home along with whatever obviously non-essential gadget wants to be recharged.