Charging rate

As more people move into “EV mode”, the same questions popup on a regular basis. Several recurrent ones are:

  1. I have a 220 V circuit with 30 A, how much do I get to charge my car? It depends on the kW charger of your car. You want a bigger kW charger for more range/h charge. It does not give you more when you feed the car 22 kW if your car only accepts 3.7 kW or 7.4 kW! Your car is the limitation! It’s very sad when, with a 7.4 kW charger available nearby, we see a 3.7 or 7.4 kW car occupying a 22 kW charger, it’s such a huge waist!! Specially if the person arriving has a 22 kW charger in the car and all 22 kW chargers are busy for slow charging cars and the only thing available is a slow 7.4 kW charger… Sad.
  2. How can I know my charging rate? For a consumption of ~200 Wh / 100 km, multiply your kWatt by 5 and you have approximately your charge rate in km/h. Divide by 1.6 to get miles. For 110 V 12 A: 110 × 12 / 1000 × 5 / 1.6 = 4 mi/h. For 220 V 30 A you get 220 × 30 ÷ 1000 × 5 ÷ 1.6 = 20.6 mi/h. 230 V 16 A 3 phase (11 kW) normally gets you 55 km/h. 32 A 3 phase (22 kW) gets you ~110 km/h.
  3. Why do I get less than the arithmetic tells? If the circuit delivers less V when loaded (typical), your W decreases and the charge rate will stabilize with less km or mi per h charging rate. A circuit delivers as much A as it can, depending on the Quality of Service and on the quality of the wire of the installation. Also, if the plug where you connect your EVSE is far away from the main distribution, you might get lower V when loading with higher A, the wire’s resistance plays an important role. Sometimes it pays to be attentive and to move to a plug near to the main energy distribution board. I’ve seen differences between 8 to 11 kW just for moving to a plug near the supply board, due to shorter wiring between the different plugs to the power supply board.
  4. As always, YMMV.

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