Bolt EV Consumption and Modelling
Entry posted by Bo-ABRP
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Thanks to the 5 Bolt EV drivers contributing driving data to ABRP, we’ve finally got enough data points to define our first real world consumption curve for the Chevy Bolt EV! We can still use driving data to improve the model even further, so if you’d like to contribute your data, have a look at the instructions. Also, if you’ve got an electric car you’d like us to support, contact myself and Bo, and we’ll run you through what we need to add the car to the planner.
Much of the data comes from day-to-day driving, with a few road trips sprinkled. Thanks to everyone who contributed their driving data!
Bolt EV Power at Constant Speed
The ABRP Model, as you know, is driven by calculating the power consumed for each leg of the trip by plugging in the speed, elevation, and other factors for each segment of the trip, determining how much power the car must output to drive that segment. It then adds up all the segments, and subtracts it from the battery to determine when a charging stop is needed.
For this purpose, we need an accurate driving model on flat ground as a baseline, that turns speeds into power. Then we can add all the other driving factors on top of that:
Bolt driving data fit to a third order polynomial
The blue dots are consumption samples (30 seconds of driving), adjusted for elevation and speed changes, and the yellow dots are median points within a 1 m/s bin. This means that the red line consumption model is fitted to the median consumption which means that most weather issues, car defects, aggressive driving and so on is typically ignored. As can be seen, we mostly have data points from very low speed and from highway speeds, but that is where things are most interesting.
For the Bolt EV, the bottom line is, it’s actually a quite efficient vehicle, though its somewhat unaerodynamic shape really hits it at high speeds. The model gives us a reference efficiency of:
- 6.06 km/kWh (165 Wh/km) at 110 km/h or
- 3.92 mi/kWh (255 Wh/mile) at 65 mph
That’s pretty good for a boxy little hatchback! For comparison, that’s about halfway between the Model 3 (143 Wh/km) and the Model S (188 Wh/km).
We’ve now updated the live model for the Chevy Bolt (and Ampera-E), so you should see the benefits of this higher efficiency in your route planning! Do note that we still set the default a little lower than that, just to ensure we give you a plan that’s not going to over-promise your car’s capabilities.
Comparing to the Analytical Model
Driving range vs speed comparison between the real world driving data and the original analytical model.
Up to this point, we’ve been using an analytical model, using the drag characteristics, rolling resistance, and other parameters to determine an approximate driving model for the Bolt. Since we’ll be building a lot of these as more EVs come to market, we wondered how accurate the analytical model really is:
As you can see, the models match quite closely! In fact, when building the Bolt analytical model, I added a 10% margin of safety to the model until we could validate using real world data, and you can see that at freeway speeds, the Analytical Bolt is about 10% lower than the Real World Bolt.
Road Tripping in the Bolt
With all the data we’ve got, let’s add the Bolt into the road table, and see where it falls:
- Model 3 Long Range: Total trip duration 09:43, of which charging 01:23
- Model S100D: Total trip duration 10:05, of which charging 01:45
- Model X100D: Total trip duration 10:29, of which charging 02:09
- Model S60: Total trip duration 10:35, of which charging 02:15
- Model X60: Total trip duration 11:28, of which charging 03:08
- Bolt EV: Total trip duration 12:20, of which charging 04:00
This is using the “ABRP hypothetical road trip” is 1000 km (621 mi) in 200 km (124 mi) steps at 120km/h (75mph). The Bolt’s overall road trip speed is pretty slow. Even slower than the slowest Tesla. This is a consequence of the relatively slow charging that Chevy has built into the Bolt:
Charge speed comparison, accounting for vehicle efficiency and battery size.
Comparing the Bolt’s charge speed to that of the Model 3, we can see why our road trip takes so long! Accounting for battery size and driving efficiency differences, the Model 3 can charge nearly 2.5 times faster than the Bolt at each relative peak. All in all, the Bolt definitely can do those road trips, but it’s going to be at a much slower overall pace than the Model 3.
The upcoming Hyundai Kona is a little bit faster than the Bolt, but not hugely, since it’s slightly less efficient. The larger battery makes for slightly longer range, but also means it takes a little longer to charge. Once we start getting some data, we’ll do a comparison to see how much faster the Kona really is than the Bolt.
Appendix: Graphs in Imperial Units
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