What's the transmit power of that little handheld supposed to be anyway?

My ICOM supposedly puts out 5 watts peak.

So what's the battery solution here? Is there a battery that can (a) handle
the output and (b) not discharge while sitting in the seat pocket?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"