Basically the Fenix 5 charge cable can be plugged in to any USB charging source, including the sort of external rechargeable batteries usually used to top up smart phones and USB charging adapters that one plugs in to a normal domestic power socket. Hope that answers what I think your question was.
@Crispin: can you name one external battery that reliably charges the 5s? I have tried a few and all stop charging after a couple of minutes, presumably due to charging current below the activity threshold.
