Battery C-rate란?

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C-rate란?

‘C-rate’는 Current Rate의 줄임말로, 배터리를 충전 또는 방전시키는 속도를 나타내는 값입니다. ‘충·방전율’이라고도 하는데요. 단위는 용량을 뜻하는 Capacity의 약자인 ‘C’를 사용합니다. C-rate는 충·방전 전류(A)를 배터리의 정격 용량 값(Ah)으로 나눈 값으로, 표준값은 1C이며, 아래와 같이 계산할 수 있습니다.

C-rate, or current rate, is a unit of measurement that indicates how quickly a battery can be charged or discharged. It's calculated by dividing the capability of a battery by its capacity. 

Here are some examples of C-rates and how they relate to charging time: 

1C: A battery is charged from 0–100% in one hour.

3C: A battery is charged three times faster than 1C, or in 20 minutes.

C/5 (or 0.2C): A battery is charged five times slower than 1C, or in five hours.

The C-rate of a battery is relative, and other factors like the cathode loading can also affect how the battery behaves. The stated capacity of a battery also varies depending on the C-rate, with faster discharge rates resulting in smaller stated capacities. 

Two main factors that limit how fast a battery can charge are thermal heating and mass transfer limitations. 



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How to Understand Battery C-Rate?

What is C rating?

The battery C Rating is the measurement of current in which a battery is charged and discharged at. The capacity of a battery is generally rated and labelled at the 1C Rate (1C current), this means a fully charged battery with a capacity of 10Ah should be able to provide 10 Amps for one hour.


C-rate의 활용

그렇다면 C-rate는 배터리 사용에 있어서 어떤 의미를 가질까요?

첫째, 충전 C-rate 값을 통해 배터리의 충전 시간을 짐작할 수 있습니다. 예를 들어, ‘10C로 충전 가능한 배터리’라는 표시를 통해서는 배터리 용량 대비 10배 용량의 전류로 충전이 가능하다는 것과 그로 인해 완충까지 최소 6분의 시간이 필요로 함을 알 수 있죠.


A battery's C rating is a measure of how quickly it can charge or discharge, and is a key factor in determining its performance. The C rating is calculated by dividing the charge or discharge current in amperes (A) by the battery's rated capacity in ampere-hours (Ah). 

C rating

Time to charge or discharge

1C : 60 minutes

0.5C : 120 minutes

2C : 30 minutes

The C rating is important for a number of reasons, including:

Performance: A battery's C rating is a key factor in its performance in applications that require a lot of power in a short amount of time, such as electric vehicles, drones, and power tools. 

Voltage drop: A higher C rating means the battery can operate with less voltage drop. 

Overheating: A C rating of 10 means the battery can discharge ten times its nominal capacity without overheating or damage. 

You can usually find a battery's C rating on the battery's label or datasheet. If not, you can contact the manufacturer.