The Exposure Revo is designed to be dynamo powered. If it can be plugged to a small battery pack as well then it could fit your bill?
Another option could be any light powered by a battery pack that is also charged by USB, and have two packs.
Cheers. Trying to minimise kit (remove need for external power supply), so carrying battery packs is a bit counter-productive! I'll look at the exposure revo in more detail. Possibly a bit pricey, but definitely the kind of thing I'm after.
@t4ny4 started
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The Exposure Revo is designed to be dynamo powered. If it can be plugged to a small battery pack as well then it could fit your bill?
Another option could be any light powered by a battery pack that is also charged by USB, and have two packs.