Avoiding Quick Charging Pitfalls
Last Updated September 4, 2012
The tips below are based on data we have collected on how the LEAF uses DC Quick Charge (DCQC) stations.
Some or all of this will also apply to the Mitsubishi iMiEV.
For the LEAF, it is useful to have an after-market
state-of-charge (SOC) meter to monitor how much energy
has actually reached the battery. Our page on predicting energy use has
additional information on this meter.
- The charge timer on your LEAF is ignored when using a DC quick charger.
- The target charge level is determined based on the SOC when you start a charge at the DCQC station. If the
charge begins with SOC below 50%, the LEAF will charge to 80%. If SOC is above 50% when DCQC
starts, the LEAF will charge to "full."
- As with Level 2 charging, "full" is typically not quite 100%. Variables such as battery
temperature will affect how much energy the car accepts before stopping the charge.
Although you'll get to 12 bars, we can see using the SOC meter that the charge level only reaches
about 95% when doing a full charge from a DCQC station. Keep in mind that charge levels as low
as about 93% will still show 12 bars.
- If you arrive at a DCQC with under 50% and want to charge to full, you'll need to restart the charge
after the car is above 50%. You can wait until the charge stops (at 80%), or can manually stop and restart
when the car shows a level above 50%. We have restarted by unplugging and then starting a new charge session;
there are also reports that you can just press the "Start Charge" button after the first charge
- When using a DCQC from under 50% to get to 80%, the LEAF's charge rate averages 400-500 Wh/minute.
When charging from over 50% to full, the charge rate averages about 200 Wh/minute,
compared to Level 2 charging which adds about 55 Wh/minute.
- When you charge at a DCQC station, you'll get about 85-90% of the station-reported kWh into your battery
- Do not assume that the SOC percentage shown by the station represents your vehicle's SOC.
The AeroVironment and Blink DC Quick Charge stations show a percentage that appears to be the car's SOC, but
it's important to understand this number is not the car's SOC and treating it as such may get you
At the beginning of a charge, the number shown on the station agrees pretty well with the car's internal
estimate of SOC, but as the charge progresses, this value will jump up much higher than the actual
SOC and keep that value, unchanging, until charging is complete. When doing a charge to 80%, the
value shown on the station will increase to 89% well before the charge completes at 80% actual SOC.
When doing a full charge, the station will display an SOC of 98% in the early stages of charging (e.g. 9
minutes into a 36-minute charge, with the car at 87%), and the car will not generally reach that high an
SOC, even by the end of charging.
- If you want to stop the charge early, do so based on the car's SOC display, not
based on the station's SOC display.
- For best results at a Blink quick charge station, always choose a 100% charge.
Because the quick charge station doesn't know the LEAF's actual SOC, it can't stop at
the charge level the user requests. Since the LEAF already has a notion of where to stop
the charge, it's best to choose 100% on the station so it will
let the car control the charge.
Tom and Cathy Saxton. You may not copy or reproduce any content from this site without our consent.