100 MPH Standing Still

Most of us agree that the Tesla Model S looks great. It might even look like it’s moving at 100 MPH standing still. Is this just hyperbole? Not if we’re talking about charging!

Here is an interesting calculation you can do to see how fast your car is charging, in miles per hour!

`MPH = Range / ((battery capacity in kWh * 1000) / (input voltage * charger output current))`

Let’s populate some of these figures and see how “fast” your car can charge:

The OEM EVSE that comes with the Mitsubishi i-MiEV (62 mile EPA range rating) is an 120V, 8A charger. The battery has a 16kWh capacity.

`MPH = 62 / ((16 * 1000) / (120 * 8))`
`MPH = 3.72`

Pretty darn slow. For every hour of charging on the L1 EVSE, I get less than 4 miles of range. 4 MPH is walking speed.

Let’s try the L2 charger I have. This is a little trickier since my Clipper Creek charger is rated at 20A, but my car can only charge at 13.75A (3300W).

`MPH = 62 / ((16 * 1000) / (240 * 13.75))`
`MPH = 12.7875`

Getting better. We’re up to jogging/running speed.

For you LEAF owners with the new 6.6kW charger:

`MPH = 75 / ((24 * 1000) / (240 * 27.5))`
`MPH = 20.625`

Still better. We’re up to sprinting speed.

Even though my i-MiEV doesn’t have an L3 (DC/CHAdeMO) charger, let’s see how fast that will go (assuming the i-MiEV can charge at full CHAdeMO speed).

`MPH = 62 / ((16 * 1000) / (440 * 62.5))`
`MPH = 106.56`

Nice. However, CHAdeMO will only allow you to charge to 80% capacity. This should be the same speed as the LEAF’s L3 charger.

Let’s go for broke with the new 120kW Tesla SuperCharger!

`MPH = 265 / ((85 * 1000) / (730 * 120))`
`MPH = 273.11`

Granted, there are some educated guesses made, but wow! The SuperCharger actually may be faster than my calculations, but that sure makes a difference.

As always, your mileage may vary. If you’re soft on the accelerator, your charging MPH will increase.