[Elecraft] K2 Power Supply?

[Tom Buchanan]

Hello to the Elecraft Group,

Based on K2 use in the field (camping, Field Day or vacationing) where
access to a 12 to 14 volt power supply isn't an option.   What is a
dependable power supply for ssb at 10 watts?   I think I read somewhere that
above 10 watts wasn't recommended on batteries.  Most of the time I will be
working CW at 5 watts or less.

I am also considering the KBT2 internal 2.9 AH battery option.  Any comments
or experiences with the KBT2?

Thanks and 73,

Tom KG4KGY
K2 #2688