2022 Select MMe with eAWD and Comfort & Tech package in Rapid Red
Hi @MRyan7465:Ok. Dumb Question alert! Sorry in advance…If a L2 EVSE delivers 20kw per hour, and an ER Mach E has roughly a 90kw battery, shouldn’t it only take roughly 4.5hrs to fully charge the car?
If I get electricity for .10 a kw, and my battery is 90kw, then wouldn’t it only cost $9 to charge my MME from 0% to 100%?
The power delivered by your EVSE is rated in watts or kilowatts. The storage capacity of your battery is rated in kWh (kilowatt·hours), or roughly, the product of the wattage supplied and the time over which it is supplied. Your electricity usage rates use the same metric - kWh, which is how much wattage you use for how long. If you use 100 watts for an hour, you've used 0.1kWh. If your car has a 90kWh battery, it can supply 1000 watts for 90 hours straight.
Charging your battery isn't quite 1:1 EVSE power to capacity. In other words, if your EVSE can deliver 20kW, it won't take exactly 90kWh / 20kW = 4.5h. There are losses, inefficiencies, and electrical & chemical restrictions. But, yeah, that's about right. It shouldn't take twice that long, but I wouldn't be surprised if it was a half hour longer.
If you pay $0.10 per kWh, and you draw 20kW for 4.5 hours, you use the 90 kWh, and you'll pay 90kWh * $0.10 per kWh which comes to $9.00. So, yes, you're in the right ballpark.