MrDRMorgan said:
Thanks for the post. Very informative. I usually charge to 90-95% when I use DCFC to charge my 2016 Spark EV. At home I charge to 100% overnight using my L2 EVSE. During hot summer nights when my garage is very hot, I use the Departure Time charging feature and set the completion time to a time past the time that will give me approximately 80% of full charge at the time I actually want to use the car the next morning. It takes a bit of experimenting to determine the end time needed to give 80% of full charge and you must take into consideration the charging rate you are using. But... it works!
So far, my highest battery temperature at the time of measurement is 88 deg. F and the lowest is 59 deg. F for the time interval of June 18 thru January 19. 38 measurements were taken during this time interval. I see similar results for my 2014 Spark EV which does not have DCFC. Battery capacity degradation over this same time interval is 0.7 kWh for my 2014 Spark EV and 0.8 kWh for my 2016 Spark EV. The degradation numbers for both cars track perfectly so I am assuming it is due to the drop in ambient temperature between June 18 and January 19. I will know this assumption is correct if these numbers continue to track together and start to rise as the ambient temperature starts rising as we move towards summer.
Regardless, I will take my TorquePro equipment with me the next time I use DCFC and see what the battery temp is immediately after a 95% charge. I need to do this in the hot summer too. This morning it was 37 deg. F outside here in Manteca, CA but my garage was 55 deg. F.
Personally, as I mentioned, I don't like fast charging past 75% or so - because heat kills. In the winter, (well, with a cold battery pack to start) it's not as important (IMO) because the pack (and its sunk heat) are cooler to start, AND the heat will radiate away faster at 40F ambient. Personally, I wouldn't want the temp of the battery to get much over 80 degrees. Also, with EVgo, you are paying by the minute and the charging rate (kW) starts dropping around 75-80% (although it doesn't get really low until 88-90% - 22-25kW). But if you need the charge for the trip (and reserve safety), you need the charge for the trip.
You must be feeling pretty spoiled now, what with all the EVgo stations that are now between Manteca and the Bay Area. One in Tracy for "OMG! I need 5 kWh to get home!!!", a whole row of sites (?4? ?7?) in Livermore/Pleasanton, 2 units (one site) in Hayward, and then a slew off I-880 on the eastshore of the bay. Quite a difference from 2-3 years ago, eh? (Note: there is a somewhat inexpensive ChargePoint 125A/50kW DCFC under the approach to the Dumbarton bridge (CA-84) in Newark : $0.12/kWh - useful for a "top up" for tooling around the bay, or before heading home if you are passing nearby. There's also an identical FREE charger up in Richmond {but that's a ways north} off I-580 at the Rosie the Riveter museum.)
I have "heat pump rpm" and "heat coolant temp" gauges enabled in Torque - I haven't seen them in use yet, due to my OCD babying of the pack.
I know that in the
Bolt, the battery cooling turns on earlier (lower bat temp), and runs/cools at a higher/faster rate if the A/C is on inside the car. Next time you are fast charging the Spark and the bat temp goes over (say) 80/81, try turning on the A/C to see if that activates the heat pump or cools the battery coolant fluid. As a data point.