The good news is your battery charger is not defective.
The CG-580 charge ONLY has a red light. It will never go green because there is no green light in it.
The CG-580 indicates charge level based on the number of blinks per second.
One blink per second = 50% or lower capacity
Two blinks per second = 50-75% capacity
Three blinks per second = 75-90% capacity
Solid (no longer blinking) means the battery is within 90% of full.
When the light finally goes solid, the battery is not technically full... Canon suggests that if you leave it on the charger for 1 more hour after you see it go solid then the charger will top-off the battery.
Your camera owner's manual will have a section on charging the battery (and it's usually right near the beginning of the manual because it's one of the first things they want you to do when you get a new camera.) It should describe this for you.
Tim Campbell
5D III, 5D IV, 60Da
