Here is a good article on LIPO Batteries. Take a look at the C and IR section. It explains allot. If your just a person that goes out to just have fun then you dont need to worry about this stuff. If you r a racer then you need to look into your batteries performance. I have a 308 Duo charger and it displays IR. Didnt know the importance in this untill this last weekend when I raced onroad for the first time in 23 years.

A Guide to Understanding LiPo Batteries