Beginner’s Guide to RC – Explanation of a LiPo Batteries “C” Rating
In this entry in our Beginner’s Guide Series, we’re looking into another one of those magical numbers on the outside of every LiPo battery; the “C” Rating.
Simply put, the “C” rating is the cell’s maximum safe continuous discharge rate. Let’s put some numbers down from a LiPo pack for reference: 5000mAh 20C 7.4V (2S).
Before we calculate the discharge rate, we need to convert the mAh to amps. There are 1000mAh in 1amp so, in this case, our 5000mAh pack is equal to 5amps. Now, simply multiply the capacity in amp hours by the packs C rating (in this case, 20C).
5000mAh = 5amps
5amps x 20(C) = 100amps continuous discharge
Using this calculation, you can see we can safely pull up to 100amps continuously from our 5000mAh 20C LiPo without doing any damage.
Let’s check out a few more scenarios:
4500mAh 40C 7.4V LiPo
4500mAh = 4.5amps
4.5amps x 40(C) = 180amps continuous discharge
7200mAh 90C 7.4V LiPo
7200mAh = 7.2amps
7.2amps x 90(C) = 648amps continuous discharge
You can plug in your own numbers from any LiPo pack and to see your safe discharge rate.
Here are two other articles you might be interested in; Understanding LiPo Battery Voltage and LiPo Battery Safety. The LiPo Battery Voltage article is an interview with one of my good friends that works in the LiPo industry. It has a lot of great info on LiPo batteries as well as squashing some misconceptions about this battery type.