summit wrote:Typically, the charge rate is around 44 kw below 70-75% SOC.
No. The Bolt's charge profile is :
* 150A until about 50% SoC (if available)
* about 105A between ~50% - ~70% SoC (if available)
If you are using a 100A ("50 kW") DCFC (EVgo has quite a few of these) you will charge between 34-ish and 38-ish kW up until 70% SoC, when the rate will drop when the car decides to pull fewer amps. (That's because the amps will remain constant while the battery pack voltage rises from around 335V to above 370V.)
If you are using a 125A (also
called "50 kW") DCFC, then you will pull between 43 and 46 kW up until around 50%
SoC, when the car decides to pull only about 105 amps, at which point the charge rate will drop down to about 38-39 kW until around 70% SoC, when it will drop to pulling 24kW (370V / 65A).
If you are using a 150A -or higher- DCFC (EVgo doesn't have many of these) then you will pull between 52 and 55 kW up until around 50%
SoC, when the car decides to pull only about 105 amps, ...just like above ...
So, using a 125A charger up to around 50% SoC (not 70%), your cost numbers are fairly accurate. Using a 100A DCFC will cost more per kWh, 150A will cost less. (The Bolt won't ever pull more than 150A even if available).
So, if you use a 125A DCFC to go from about 10% to about 50% (22 kWh), it will take about 30 minutes, 30*0.2=$6 : 6/22= 27 cents/kWh.
If you use a 150A DCFC to go from about 10% to about 50% (22 kWh), it will take about 25 minutes, 25*0.2=$5 : 5/22= 23 cents/kWh.
IF you have a 125A EVgo unit reasonably placed, and if think you can easily and conveniently put 50 kWh into your Bolt at lower SoC, subscribing to EVgo might be a good way to go, as the per-minute charge is $0.15 when you subscribe - it costs $10/mo, but the first $10 (66 minutes) of fast charging is included.
If you use a 125A DCFC for 20 minutes when between 10% - 50% state of charge, 15 kWh, 20min @ .15= $3. If you do that 3 times a month (to use up the "free, included" DCFC minutes) you only pay about $0.20/kWh and still have the cheaper rate available for traveling. It's even less expensive (per kWh) if you have a 150A DCFC available.