Saturday, December 31, 2016

LA to SF: At the airport

Finally made it to SFO to pick up my friends with about 30 minutes to spare! The drive and charging took a lot longer than I had estimated but I think if I did not have the one leg with the bad weather it would have been a lot more reasonable.

Things I would take away from this:
- You cannot be in a hurry to take a long trip!
- Check the weather and wind before you leave and account for that
- Check the types of chargers you are going to be using; I assumed all EVgo put out 50 kW, but thats not the case
- If it's cold dress warm and use the seat heaters! Also precondition when you are hooked up to the charger!
- You will never get 50 kW out of the charger, I do not think I saw over 45 at any time even at low SoC

Stats for the final leg:
Temp: ~45-50F
Speed: 70 mph
Wind: None
Cabin heat: Off except for 5 minutes to clear the window once, two seat heaters on low
Miles: 134.4
Total kWh used: 40.2 (81%-14%)
Efficiency: 299 Wh/mi or 3.34 mi/kWh
Charging start: 6:29pm, 29mi range, 14% SoC
Charging finish: 7:04pm, 91mi range, 49% SoC (Also includes 2 minutes on the phone with EVgo)


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  2. A 50 kW charger is rated for 500 volt, 100 amp. Since the voltage is set by the battery voltage, you will never achieve 50 kW charging. Low SOC will have batteries with lower voltage and high SOC will have batteries with full voltage.

    Low SOC
    333 volt * 100 amp = 33.3 kW
    The voltage is low, current is max.

    Mid SOC
    400 volt (?) * 100 amp = 40 kW
    The voltage and current is max.

    High SOC
    400 volt * 50 amp = 20 kW
    The voltage is max, the current will go down as your SOC gets higher.

    There are some DC fast chargers with 62.5 kW which would give you 125 amps. There is a new charger coming online in 7 months rated at 350 kW (1000 volt, 350 amp). Hopefully, the Bolt EV can handle 160 amps.

    1. Very good post. Also I believe EVgo is adding/upgrading some 80KW CCS stations. So that would be interesting to see as well.

    2. EvGo is going 350 kW. The first one is coming to Baker, CA that has 4 charging stations.

      The sweet spot for the Bolt EV would have been charging within 25% SOC to 75% SOC window. 30 minute charging, in that window, would have add about 22 kWh in 30 minutes.

  3. Thank you for a good post. Please also note that voltage/amps is reduced downwards at low temperatures because the electrons cannot move that fast in cold weather (it may hurt the battery). This gets especially intrusive at sub 32 degrees fahrenheit, but it´s still a factor up until 60 degrees fahrenheit.