C-rating | Time |
---|---|
30C | 2 minutes |
20C | 3 minutes |
10C | 6 minutes |
5C | 12 minutes |
2C | 30 minutes |
1C | 1 hour |
0.5C or C/2 | 2 hour |
0.2C or C/5 | 5 hour |
0.1C or C/10 | 10 hour |
0.05C or C/20 | 20 hour |
As we can observe, a battery with higher C-rating can deliver/receive more current with its available stored energy. Common C-rating of batteries is 1C.
How to Calculate C-rating
Calculating the charging and/or discharging time of a battery through its C-rating is simple:
t = 1 / Cr (to view in hours)
t = 60 minutes / Cr (to view in minutes)
Where:
t = Time
Cr = C Rate
Sample Calculations:
1000mAh , 0.5C battery
0.5C x 1000mA = 500mA max
1/0.5C = 2hours
60/0.5C = 120 minutes
1000mAh , 1C battery
1C x 1000mA = 1000mA max
1/1C = 1 hour
60/1C = 1hour
1000mAh, 2C battery
2C x 1000mA = 2000mA max
1/2C = 0.5 hours
60/2C=30 minutes
You can also calculate output currency, power and energy of a particular battery using:
I = Cr * Er
Cr = I / Er
Where:
Er = Rated energy (Ah)
Cr = C Rate
I = Current of charge or discharge (Amps)
USAGE OF HIGH and LOW C-RATED BATTERIES
Batteries with higher C-rating tends to be more inviting to everyone. Imagine being able to charge and discharge your power pack faster than the rest - But, there is something you need to know about; at higher C-rates, you may experience lost capacities of around 5% or more due to heating effects. This means, if you need your battery to stick with its actual energy storage specs, you might want to turn the volume down a little bit. Higher C-rated batteries are best for application that requires such - Drones, etc. Using higher C-rated batteries, they can burst more energy to motors when they need to. However, some conventional battery types such as lithium based batteries are originally designed with higher C-rating compared to the rest and still able to have very good performance. So, to sum it all up, before you choose the type of battery and C-rating to use, you need to research first about their their composition and performance based on their datasheets.
-Paul Custan is an Electrical Engineer who have worked as a software engineer and as a digital platform specialist before becoming a full-time FNX Solar employee. FNX Solar Power Solutions Inc. is a business based in Canada. We develop and sell portable power stations and related accessories.
Thank you @john_cameron for the cover photo used in this article