We did nearly 900 km from Portland ME to Annapolis MD yesterday with stops in W. Hartford CT and Hamilton Township NJ. Two weeks ago we made the reverse trip with three stops because we didn't skip the unnecessary superchargers. Through both of these trips we noticed a consistent behavior of the energy estimate that is a bit puzzling. When we strike out on any given leg, our estimated SOC at trip's end initially drops noticeably and disconcertingly, for example from 20% to 12%. In some cases we got a message telling us to drive slowly to make the destination. Fortunately, this trend ends after 10 minutes or so and reverses, with the estimated ending SOC rising to the initial estimate or above, depending on driving speed. As the estimated margin grows, we of course increased speed in an attempt to use that energy, which is a nice payback for initial conservatism provoked by the initial decline.
Consistently, we also saw an initial consumption rate that was higher than normal, and this appears to be what is driving the estimated margin downward, because as the consumption returns to normal, the original margin estimate does as well. They appear to be closely tied together, because climbing a grade can also cause the estimated margin to decline, or vice versa.
This leaves me speculating that the entire energy estimate is driven by the recent consumption record, which is "normal" when we arrive at a supercharger, but then rises for a while upon leaving the supercharger, eventually returning to normal. My question is then what drives the consumption upward upon departing from a supercharger? Is it that the cooling system continues to cool the battery down after charging at high power? The problem with that explanation is that we also see a similar effect when starting out from our NEMA 14-50 charger that never exceeds 10 kW.
Could it simply be that energy drawn from the battery while the car is stationary is eventually bookkept into the initial consumption for some period when getting moving again?
Any thoughts would be appreciated. This is a puzzling behavior, but also much preferable to the opposite situation in which the projected consumption is underestimated and leads to a persistent deficit that grows with travel time.