found here is some great battery information,
https://www.rcnitrotalk.com/forum/showthread.php?t=48879
but here is a nice explaination posted by rolex on the same page second or third post down.....
What is C in relation to batteries?
C ratings are simply a way of talking about charge and discharge rates for batteries.
1C, = 1 time the rated mah capacity of the battery. So if you charge your 650 mah pack at 1C, you charge it a 650 miliamps, or .650 amps.
1C on an 1100 pack would be 1.1 amps.
2 C on your 1100 pack would be 2.2 amps
Motor batteries are often rated in Discharge C and charge C.
So an 1100 mAh pack (1.1 amp hour) might be rated for 10C discharge, so you can pull 11 amps ( flow ) without damaging the battery.
Then it might be rated at 2C charge rate (flow), so you charge it at 2.2 amps (2200 mAh)
If you have a 500 mAh pack - any kind - and it is rated at 16C that means it can deliver 8 amps.
If you have a 1000 mAh pack - any kind - and it is rated at 8C that means it can deliver 8 amps.
If you have a 1000 mAh pack - any kind - and it is rated at 12C that means it can deliver 12 amps
If you have a 1500 mAh pack - any kind - and it is rated at 8C that means it can deliver 12 amps
If you have a 1500 mAh pack - any kind - and it is rated at 20 C that means it can deliver 30 amps.
If you have a 3000 mAh pack - any kind - and it is rated at 10 C that means it can deliver 30 amps.
So, if you need 12 amps you can use a pack with a higher C rating or a pack with a higher mAh rating to get to needed amp delivery level.
One last point. Motor batteries vs. receiver batteries
Some batteries can sustain high discharge rates. Others can not.
Those used as transmitter/receiver packs typically are made for low flow/amp rates while those made for motor packs can sustain higher rates.
Having a 600 mAh pack does not tell you if it is a motor pack that can put out 6 amps, or if it is a transmitter/receiver pack that would be damaged if you tried to pull power at 6 amps. It is enough to say that they are different.
A motor pack could be used for a transmitter/receiver job, but a transmitter/receiver pack should not generally be used as a motor pack.
It is best to size your battery packs so they run somewhat below their maximum C rating. You will stress them less and they will last longer. For example, if your motor needs a pack that can deliver 10 amps, getting a 1000 mAh pack that is rated for 10C ( 10 amps ) will meet the spec, but it is running at its limit. A 15 C rated 1000 mAh pack would be better, or perhaps a 1300 mAh 10 C pack. In either of these cases, the pack will be less stressed and should handle the load much better over the long term.