[Elecraft] battery pack query

[R & L Webb]

Gents,

I've just purchased a KX1 and I expect to use it on vacations etc.  

What is the collective thinking for an outboard 12VDC rechargeable battery pack I can use with this little gem?

I'm looking for something that I can take away with me that will last for a week or so without recharging using the rig intermittently.  I know that if I were to use it in a Field Day or other continuous mode situation,  I'd want to take along a recharger or some sort. (solar cells?)

I've seen small amp-hour gel cells, but there might be something else out there that I've missed.

Thanks for the help.

Ralph Webb, VE7OM