Thumbs Up !!!! Honest Marketing will pay off in the end. :thumbsup:Theoretically, it is supposed to stand for the maximum continuous discharge rate the battery is capable of, as a multiple of its capacity. So a 10C 5000 mAHr battery (which is 5AH) can be safely discharged at 50 amps (10C X 5AH).
But for all practical purposes, nowadays, it is just a marketing number that bears little resemblance to the actual capabilty of the batteries. Example: a 6000 mAHr battery rated at 90C would be 540 amps. Neither the wires, nor the solder, nor the connectors (and probablyt not the cell itself) could withstand 540 amps even for the 40 seconds it would take to dump the pack at 540 amps.
One company tried labelling batteries with an honest C-rate based on a well defined measurement standard and they didn't sell because the number was too low in comparison to other manufacturers labels.
Read about it here: http://www.hobbytalk.com/bbs1/showthread.php?t=357870 and here http://www.hobbytalk.com/bbs1/showthread.php?t=372760