Huck,

You are right, it is a bit "short hand" for me also...

I understand the "C" rating is the discharge capacity of the pack. This is a combination of the amps available (or milliamps) and the 'rate' at which the power can be delivered.

So: my pack it 2200 milliamps and has a rating of 15C

2200milliamps/1000 milliamps per amp = 2.2 amps of power

My battery has a 15C rating so: 2.2 amps X 15C = 33 amps;...

So this setup can deliver 33 amps of power to the speed control/motor... Now if you need something like 45 amps you will either need to get a bigger pack (more millamps) or a better C rating...

This is what I have gleaned from several sources including; RCGroups guide to Lithium polymer batteries, Battery University, and the thread here from Aeajr (EVERYTHING YOU WANT TO KNOW ABOUT ELECTRIC FLIGHT)...

There is a lot better detail at these sources and others...