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What does C as a unit mean in this context?

From the article:

> The power-focused variants were delivering densities of 80 and 100 Wh/kg, and were charging and discharging at 10 and 20C.

I don't think it is Celsius, and Coulombs (which would be the correct SI unit) doesn't really make sense. Some number of Amps would make sense, but 10 or 20 isn't very impressive.

Does any one know?

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"A C-rate of 1C is also known as a one-hour discharge; 0.5C or C/2 is a two-hour discharge and 0.2C or C/5 is a 5-hour discharge. Some high-performance batteries can be charged and discharged above 1C with moderate stress."

https://batteryuniversity.com/learn/article/what_is_the_c_ra...

Ah, ha - thank you :-)

Racing drone batteries can be charged around 4C and discharged at close to 100C (Unsure how many of those C is marketing), but then I think they safely qualify as high stress..

Seems to be C-rate[1], a unit specifically for battery discharge rate. Funny enough, the wiki article does mention disambiguation between it and Coulombs.

[1] https://en.wikipedia.org/wiki/Battery_(electricity)#C_rate

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