C-rate is a measure of the rate at which a battery is charged or discharged relative to its capacity. It is the charge or discharge current in Amps divided by the cell capacity in Ampere-hours.

A 1C rate means that the discharge current will discharge the entire battery in 1 hour.

If we plot charge / discharge rates in Amps versus battery capacity in Ampere-hours we get straight lines for a given C-rate.


A battery electric vehicle would have a peak (10s) discharge rate up to around 5C, the charge rate would be around 2C (hence it would fast charge in 30 minutes). A mobile phone on the other hand would have a discharge rate of around C/10 meaning it would last around 10 hours if it was being used. Again it would have a fast charge rate of around 2C and hence charge in 30 minutes,

However, the capacity of the Tesla is around 250Ah and the phone is around 2.5Ah (or 2500mAh). Difficult to display these on the same graph.

A hybrid electric vehicle would have a very small capacity battery of a few Ah and yet will be expected to deliver a few hundred Amps. These batteries are often capable of 40C charge and discharge. This would though be operating over a very narrow usable SoC window.

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