[madmonkey]

was nice incase your not able to find a outlet to charge your battery

 

[msing539]

You could carry a little power bank.

 

[Hacker Harrier]

I've used the USB power bank solution. It wasn't ideal, you really need a very short cable between the two for portability.

My preference would be to carry a very small DAP as a backup.

 

[dunring]

On eBay I bet you could find an old player like the Logitech I had with 1 AA battery. I scan there all the time and they sell Tandy stuff from Radio Shack and cassette decks. Mercari has a ton of old tech for sale too.