In reply to jethro kiernan:
Quick reminder (as always on these threads) that Anker power banks are identical to most others, in that they are a bunch of cheap, generic 18650 batteries with a charge controller and plastic case, and are essentially the same as all other power banks that didn't game the amazon rankings. They're fine for around town but not robust, not weatherproof and are crap in the cold.
For me for your purpose: always goal zero. Never failed me in all sorts of uses across the Arctic and remote locations, where I really can't afford them to fail.