What does the c rating mean on a lipo battery

C rating is related to lipo discharge rate

C rating is one of the most important factors to consider when purchasing a lithium polymer battery for RC devices. It represents the level of speed at which energy can be released from the battery. This rating is combined with the capacity of the battery to determine the maximum of discharge. Some machines draw very high amps from the motor and the battery needs to discharge quickly. Some people sometimes choose a battery that can't withstand the current required by brushless motors and steep props, which can cause the battery to discharge too quickly, which is not good for battery life. So when choosing C rating, you need to calculate the current you need in advance.

Maximum safe current calculation formula: Max Current Draw = battery Capacity(A) x C-Rating

Take the ovonic lipo battery 1550mah 5s 100C and 4500mah 6s 50C as an example below (note the calculation in amps)

1550mah 5s 100C: Max Current Draw = 1.55A x 100C=155A

4500mah 6s 50C : Max Current Draw = 4.5A x 50C=225A

This means that we can discharge 155/230 amps continuously without damaging the battery. It may also be noted that increasing the C rating or increasing the battery capacity can increase Max Current Draw.

It should be noted that when discharging a battery by using a battery analyzer capable of applying different C rates, a higher C rate will result in a lower capacity reading and vice versa. By discharging the 1Ah battery at a faster 2C rate or 2A, the battery should ideally provide full capacity in 30 minutes. The sum should be the same because the same amount of energy is allocated in a shorter time. In fact, internal losses convert some energy into heat and reduce the resulting capacity to about 95% or less. Discharging the same battery at a current of 0.5 C or 2 hours at 500 mA may increase the capacity to more than 100%.

If you are using a multiquad aircraft with more than one motor, you should pay attention to the number of motors. If there are n motors, the Max Current of each motor can draw 1/n of Max Current Draw.

C rating is also related to the charging rate

The C rating is also used to indicate the speed at which the LiPo battery is charged (or how much current is pumped into LiPo when charging).

Charging LiPo under 1C is a recommendation of most manufacturers. Charging the battery at a rate of 1 C means charging the battery capacity. For example, for a 4S 1550 mAh battery pack, 1 C means 1550 mA, that is, it should be charged at 1.55 amp, while 4500 mAh battery uses 4.5 amp charge, and so on.

Although increasing the C rating of charging can shorten the charging time, for the life of the battery, even if the rated C rating of the battery is higher, the battery should be charged without exceeding 1C.