Commercial EV manufacturers batteries are not required to discharge at high C rates because they run much higher voltages. There is no reason they should spend that kind of money on a high discharge rate battery. All they need is 5C or less for acceleration, and they cruise on Sub C rates of C/2 to C/5.

I agree that they don't need high rates, but this has nothing to do with voltage. Current EVs usually run at about 360 volts (so 80 kW is 222 A @ 360 V, 74 A per cell with 3 cells in parallel), but if they ran at half the voltage they would run at twice the current using the same total pack size with half the number of cells in series and twice the number in parallel (so 444 A @ 180 V, still 74 A per cell with 6 cells in parallel), leading to exactly the same discharge current for the same cells, or the same "C" rate.

I think "C" rate is an annoying term, because it involves time but values are given without using time units. C/1 rate means discharging at the rate which would fully discharge in one hour... and specifically one

*hour*, not one second or one day or any other time unit. So since a practical EV needs to run for a few hours to go far enough to use the full range (at sensible road speeds) the rate is C divided by a few (hours). At most, I suppose you could discharge an e-Golf in just under an hour driving at constant speed as fast as it would go, so that's around C/1.

A 5C discharge rate would use the full capacity is 1/5th of an hour, and of course no one will drive the vehicle so hard in street use that the battery runs out in 12 minutes. As I showed in an earlier post, the e-Golf (like the 24 kWh Nissan Leaf) only runs at 3C even at maximum acceleration effort, although an AWD Tesla "Performance" model can run higher than that (because it has four times as much battery but more than four times the maximum motor power).

At the very minimum the battery must be fully capable of delivering the maximum Discharge Rate that will be encountered.

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Of course no EV manufacture would do that because RANGE is the name of the game, and they design on minimum RANGE, and Discharge Rates take care of themselves because they will be much lower.

I agree, in general. Discharge rate is low - and not a problem - for most EVs because their major constraint is total energy capacity, not power capability. You can express this in current, but working it out in terms of power gives the same result.

Although it's not a problem, discharge rate is a design concern for EVs. The need for active cooling depends on the cell and module design, and the discharge rate to be accommodated.

Plug-in hybrids have more of a power issue, as they generally (and in pure series hybrids, always) must deliver full power to the motor entirely from the battery, yet have a relatively small battery (compared to battery-only EVs). Average discharge rate can easily be over 1C, since their range is shorter than the distance they can cover in one hour; discharge rate during acceleration is much higher. This means that discharge rate - not just energy storage - is a design concern. GM has published a maximum (for 10 seconds) discharge rate for the first-gen Volt battery of 110 kW; with only 16 kWh of nominal capacity, that's C/7... so now you see a reason that the Volt battery is popular with DIY builders, even though the Volt is only a hybrid.