I’d really appreciate a bit more detail (but in layman’s terms) of the kWh thing, and what it means when it comes to charging and range.
Lets see if I can break it down in electrical terms easily.
A kilowatt-hour commonly seen as kWh sustained in one hour. Your electricity company bills you per kWh. A kW is equal 1000 Watts,
Lets take a couple of examples:
A 1000W (1kW) hairdryer will take 1 hour of sustained use to consume 1kW of electricity or 1 kWh
A 100W light bulb will take 10 hours of sustained use for it to consume 1kW of electricity or 1 kWh
A 50W light bulb will take 2o hours of sustained use for it to consume 1kW of electricity or 1 kWh
If you run say the 100w light bulb for 1 hour of sustained use, it would consume one tenth or 0.1 of a kW or 0.1 of a kWh, so the 100W light bulb will take 10 hours of sustained use to use 1kW of electricity or 1kWh.
To find out how much an appliance costs to run for a period of time by: Multiply the device’s wattage by the number of hours you use it per day, and divide this number by 1000 to get the daily kilowatt-hour and multiply it by you price per kW.
100w light bulb x (number of hours) / 1000 x £/p per kW of electricity chargerd = cost to run for x hour/s £/p
A battery in this case one in a EV follows basically the same rules, however because we have a constant supply of electricity at home it has no effect on the load (energy) we want from it. Where as a battery can only hold an amount of energy dependant on its size and is affected by external infulences such as your right foot (load) similar to an ICE you demand at anyone time, along with temperature changes – winter and summer (although are summers aren’t really hot enough to have any negative inpits etc….
Charging an EV battery depends on the size of the battery in kWh, how much charge (energy) is in it and the charge rate of the device you are using to charge the battery with.
Let’s say your charging a 75 kWh EV battery from a 7.4 kW wall box, it will take 10 hours to charge from a dead flat battery (75/7.4=10.1 hours) A little bit of maths you can easily work out the time to charge the battery if it had 20% charge left in it and time to charge to 100% or 80% which is the norm depending on the power rating of charger used.
Knowing a EV is measured in kWh. As with your house a kWh is a measure of energy used by an appliance or EV if it were kept running for one hour. However a kW, is a measure of instantaneous power. Apliances in your home and electric motors in an EV all have a watt (W) or kilowatt (kW) rating. This is a measure of how much power they need to be continuously supplied with, in order to run.
If you have for example an electric motor rated at 200 kW at peak power output – if you ran that motor for 30 minutes you would use 100 kWh of energy — 200 x 0.5 (of an hour) equals 100 kWh.
So moving on to calculating range per:
To calculate efficiency, you need to know the distance you went, and how much energy you used during that distance. Divide the distance you went by the energy used.
So taking the same 75kWh battery and you charged to full before you drove 100 miles, and you now have 55 kWh left – you divide 100 by 20, and your efficiency is 5 miles per kWh.
Similar to how we calculate mpg frm a full tank and calculate when we fill up after we have used x amount of a tank of petrol or diesel. EV users often only charge to 80% so that is treated as full and the same calculation can be done.
You can also calculate how many miles you should get from a full charge by knowing the range the manufacturer said you should get and thevehicles battery capacity. by dividing the range by battery capacity kWh:
339 miles (quoted by manufacturer) / 75 (kWh battery) = 4.52 miles per kWh:
However with external influences its rarely accurate!
Hope it helps and hasnt confused you even more lol.