Cost of Public DC Fast Charging
Why am I doing this now:
1) Electricity America(EA) announced price changes coming in March 2023
2) EVgo announced in February 2023 a changed price structure in Michigan to per kWh
3) I thought it would be good to look at the cost structures and let people know the costs.
Framework/Assumptions:
Average battery size 66.8kWh
(https://ev-database.org/cheatsheet/useable-battery-capacity-electric-car)
DC fast charge session of 10% to 80%.
Total kWh to be charged in an average session 46.76 kWh.
Study covers an infrequent use case of one session per month, or four sessions per month. Also reviewed is a higher use case of 10 sessions in a month, to cover more driving, or the use case of no at home charging is available, and only using the public providers. At an average rate of 3 miles per kWh, this would give you 140, 560, or 1400 miles per month depending on the number of charges.
There are multiple providers I will be comparing and evaluating against the comparable cost of doing this charging at home. The providing networks covered are Electrify America(EA), EVgo, and Shell Recharge. I left out ChargePoint because there is no fixed cost structure for them. Each station owner can set the price and this can include per minute costs, large variation in per kWh costs, and various connection or per session costs. Also, the big two Electrify America and EVgo both have membership plans. Electrify America is a single member cost/tier, and EVgo has multiple member costs/tiers. Finally, to add to the confusion EVgo is also doing different costs at different times of day.
The baseline per kWh costs I have used for this comparison are $0.18 for at home charging, $0.30 Shell Recharge(using the cost of one location nearby, price may vary from location to location), $0.48 Electrify America (non-member), $0.36 Electrify America (member with $4 monthly payment). EVgo has time of day so each member level has 3 different prices, one for Midnight to 8am, one for 8am to 2pm or 9pm to midnight, and one for 2pm to 9pm. EVgo prices: $0.40, $0.47, $0.54 (non-member, plus $0.99 session fee) or $0.40, $0.47, $0.54 (Basic Member with $0.99 monthly payment) or $0.33, $0.39, $0.45 (Plus Member with $6.99 monthly payment)
Baseline cost structures in place, the cost comparison to do 1 charge session per month. This one charge would cost $8.42 at home, $14.03 at Shell Recharge, $19.69/$22.97/$26.24 with EVgo (no member or Basic Member), $22.42/$25.23/$28.03 with EVgo Plus Member, $20.83 with Electrify America Membership, and $22.44 with Electrify America no membership. Obviously, it doesn’t make sense to pay the EVgo Plus Member rate for only one session per month. Still, excluding those numbers, it can cost four times as much to charge in public as it does at home, for just one charge up from 10% to 80%.
Now, maybe the month includes a road trip and will need to stop 4 times to charge. What is that going to cost, compared to what it would cost at home? These four charges would cost: $33.67 at home, $56.11 at Shell Recharge, $78.78- $104.96 with EVgo (no membership), $75.81-$101.99 with EVgo (Basic Member), $68.71-$91.16 with EVgo (Plus Member), $89.78 with Electrify America, or $71.33 with Electrify America (Membership). The costs here range from $33 at home to between $56 to $105 depending on public charging costs on the road.
I looked at one more use case, what about charging 10 times per month. Roughly 2 to 3 times per week. This could potentially be the case if there is no access to charge at home. These ten charges would cost: $84.17 at home, $140.28 at Shell Recharge, $196.94-$262.40 with EVgo (no membership), $188.03-$253.49 with EVgo (Basic Member), $161.30-$217.41 with EVgo (Plus Member), $224.45 with Electrify America, or $172.34 with Electrify America (Membership). Again, a wide range of costs between $140 to $262 (almost double) for the same amount of energy. Even within EVgo, depending on the plan and time of day, the cost can vary from $161 to $262.
What does this breakdown to in costs per mile in best and worst case, and how does that compare to a gas car? Looking at the 10 charges per month case, the at home cost is $84.17 and that is estimated to provide 1400 miles for the month, or about $0.06 per mile. In the Electrify America Member use case at $172.34 this comes out to about $0.12 per mile. Compare that to the average gas car cost per mile of ($3.30 per gallon and 28 miles per gallon) and public charging costs about the same $0.12 per mile. Put another way to go the same 1400 miles in a gas car getting 28 miles per gallon, would have cost $165 in gas.
Charging at home is the cost and convenience winner.
Note these are all some averages and estimates. Costs vary by location and vehicle battery sizes and efficiency will differ by model. All information is for comparison purposes only.
Side note: Time is money, the referenced Shell Recharge station used in this example is a 50kW station, the EVgo and Electrify America locations often offer faster charging. So, even if the Shell Recharge looks like a better deal, it may require more time spent charging to get that savings.
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