Question about your rechargeable batterys.

If I buy this-

http://www.scan.co.uk/products/produ...oductID=361978

Will it charge with a mp3 player connected to USB? Or do I need to buy this aswell-

http://www.scan.co.uk/products/produ...oductID=361977

Thanks for your time.

It would be entirely down to whether the MP3 player had a charging circuit, it's got nothing to do with the batteries. I'm 99% certain the types of MP3 players which use AA batteries don't have charging circuits either. You'll need the charger.

Yes, you will need a charger to charge them.