EV calculations

  • Drivingforfun's Avatar
    I’m aware of how various range figures and things are calculated with EVs based on their kilowatt hours but wondered something else which I don’t see mentioned

    If you divide the battery capacity by the maximum output, does this give the time the car would run for while producing that amount of power, i.e. presumably at full throttle?

    Taking the MINI Cooper SE which has 160KW (218bhp) power and 54KW/H battery; 54/160 is 20 mins and 15 seconds

    If you multiply that by its top speed of 106mph it suggests it would go 35.8 miles at full throttle, presumably under ideal conditions

    I’m aware no one would drive like that and the range is probably comparable to that of a petrol car driven at the redline, I’m not trying to criticise, was just curious

    Is this all correct or did I oversimplify or something?
  • 3 Replies

  • Mark07's Avatar
    Community Manager
    I've heard stories where you put your foot down in high performance/thirsty petrol cars and can actually see the petrol guage go down.

    We're still in the early days of EV's and tech will improve. The Ford Model T did 10-15mpg, a 2019 Vauxhall Corsa can achieve ~70mpg.
  • Drivingforfun's Avatar
    That's all true Mark and I tried to make that clear in my original post, I'm aware some evangelists will automatically see any curious questioning as opposition and there's nothing I can do about that, but it's really not my intention - my question was purely to ask if my maths was right or is it less simple than I'm trying to make out??

    But yeah I'm well aware of mpg when driven hard, it's not unusual to get a dozen laps of a 1.5 mile track from half a tank!! 😯
  • Rolebama's Avatar
    I think your math is right. Most of my rc aircraft use 3.5Ah batteries powering 20Ah motors, and although they are not running flat out, around ten minutes is a safe flying time. As batteries lose power they build up resistance, so you won't get full power from them as they run down. (Some of the more sophisticated ones I use shut themselves down gradually before getting anywhere near flat to maintain integrity.)