Published on February 19th, 2019 | by Kyle Field
February 19th, 2019 by Kyle Field
Electric Vehicle Road Trip (EVRT) Middle East tested the limits of today’s electric vehicles in a region of the world that would not be at the top of the list for EV adoption.
Despite the climate and the region’s dependence on oil — as fuel for the residents’ vehicles and their economies — there is not stopping EVs from coming into the region.
This year, EVRT Middle East took participants up to the top of the highest peak in the United Arab Emirates (UAE) to put the participating vehicles to the test in the Regeneration Challenge.
The premise is simple: drive up to the top of 1,934 meter (6,345 foot) Jebel Jais and see how much energy the vehicles can regenerate on the way down. For the competition, the EVRT team put the three types of EVs on the trip to the test: a Tesla Model S P100D, a Renault Zoe, and a Chevrolet Bolt.
Regeneration is a bit of EV magic that represents a significant advantage over gas and diesel vehicles because it allows the car to convert their kinetic (moving) and potential (elevation) energy back into stored energy in the battery. Internal combustion vehicles are inferior in just about every way when it comes to going downhill because they have no way to recoup the energy used to get up the mountain in the first place. It is even worse than that, as they have to toast their brakes going downhill just to burn off that extra energy with friction and heat.
EVs gain an advantage by actually engaging their motors in reverse to generate electricity, charging the battery as they roll down the hill. It is a beautiful thing and something that was fun to test in a head to head competition.
Each of the vehicles in the challenge has its own advantages and disadvantages. The Chevy Bolt, for instance, has a manual paddle on the steering wheel that can be pulled to manually engage the regeneration capability of the vehicle and can even bring the car to a complete stop.
The Tesla Model S has two regen modes — Standard or Low. From there, the car takes care of the rest, but offers little in terms of manual control of regen. Though, gentle braking pressure can be used to engage regen, but risks activating the disc brakes in the car.
I was very familiar with the first two vehicles, but ended up in the Renault Zoe for the challenge. It performed flawlessly as CleanTechnica reader Charlotte and I glided down the hill at speeds ranging from 15 to 40 km/h, maximizing regen along the way. The main challenge in the challenge was maintaining sufficient spacing between the various competing vehicles and the camera crews in order to maximize regen and minimize the use of the brakes.
Regeneration is best determined by taking a few factors into account. First off, most vehicles can roll for several kilometers downhill on a mountain like Jebel Jais, so we need to look at the number of kilometers traveled without using any power from the battery. This should be the same for all vehicles in the challenge, as they have a common start and end point.
Second is the number of kilowatt-hours put back into the battery. In some vehicles, this is a very clear number that can be seen in the trip computer. For others, it must use the less accurate calculation based on the average consumption per kilometer (which will be negative) times the number of kilometers traveled. For example, it could be -0.15 kWh/km across 16 kilometers for a total regeneration of 2.4 kWh.
Third and completely inaccurate is comparing the estimated range of the battery pack at the start of the challenge and at the end of the challenge. If the vehicle had a starting range of 200 kilometers and ends with an estimated range of 225 kilometers, we might surmise that we gained back 25 kilometers of range divided by the average consumption of the vehicle in kilometers traveled per kilowatt-hour. Because all EVs use a different formula to calculate this, it is not a linear metric within a single car, let alone across several different models.
At the end of the day, we learned that the Chevrolet Bolt was the most efficient at regenerating power down the hill and took the crown at the 2019 Regeneration Challenge on this Electric Vehicle Road Trip. For next year, the EVRT team is looking at tapping into the onboard computer to pull more data out as a means of calculating the winner in a more standardized way.
The Regeneration Challenge was a great way to show participants in the road trip just how powerful regeneration is and how much of a game-changer it sometimes is for EVs compared to gasoline and diesel vehicles.
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