The charging and discharging rate of a battery is controlled by the battery C rating, which is a measure of the battery charging or battery discharging current and the charging or discharging speed. In lithium-ion batteries, the C rating is critical, and it directly affects the performance, safety and service life of the battery. By understanding the C rating, we can select a battery that meets the needs of their equipment under power, ensuring optimal performance without risk of damage or failure, and can help us measure the output potential of the battery to maximize battery life and ensure safe and efficient operation in a variety of applications.
The Battery C Rating Chart outlines the relationship between a battery’s C-rate and the corresponding discharge time. The C-rate represents the discharge rate relative to the battery’s capacity, and the time represents the expected discharge time at each C-rate. We can understand how different C rates affect the discharge time of a battery to help us select the right battery for a particular power requirement and application.
For example, Battery 1 has a nominal capacity (C/10) of 120Ah, and Battery 2 has a nominal capacity (C/20) of 120Ah, and our requirement is for a battery capable of delivering 12A of current for 10 hours of discharge time (i.e., 120Ah), then Battery 2 will not be able to satisfy this condition, and Battery 2’s nominal capacity is appropriate, but the capacity applies to the discharge rate of 20 hours, which is the only one that can meet the requirement. meets the requirement.
| Battery C Rate | Discharge Time |
| 1C | 1 hour |
| 2C | 30 minutes |
| 5C | 12 minutes |
| 0.5C or C/2 | 2 hours |
| 0.2C or C/5 | 5 hours |
| 0.1C or C/10 | 10 hours |
C (rate) = maximum discharge current or maximum charge current in amps / nominal capacity of the battery
3.1 For example, if we have a lithium-ion battery with a rated capacity of 100Ah and a maximum discharge current of 100A, what is the C rating of the battery?
C=100A/100Ah=1C
So, the rate of the battery is 1C and the expected discharge time is 1 hour.
3.2 For example, if we have a lead-acid battery, the rated capacity of the battery is 120Ah and the C rating of the battery is 2C, then what is the charging time of the battery?
Charging time = 120Ah x 2C = 4 hours
