Watch As Audi E-Tron Gains Energy Downhill


An impressive amount of battery charge is regained while rolling downhill

The Audi e-tron is the German car company’s first all-electric vehicle. It’s not a funky looking futuristic piece of machinery, but a rather tame and classy looking SUV (Sports Activity Vehicle).

Thanks to its design and functionality, it caters to the current Audi clientele quite well. After all, it resembles the current Audi Q5 and Q7, making the transition to the electric powertrain an easy feat, even by the hardest opposers of electric tech.

Thanks to its electric battery and motors, it can accelerate from 0-62mph (0-100km/h) in just 6 seconds. The vehicle is powered by a 95-kWh battery pack and promises a 249-mile (400 kilometers) range on a single charge. According to Audi, the e-tron can recharge to 80 percent battery status in less than half an hour, when utilizing a DC charging station.

To test how well the Audi e-tron performs in various conditions, the crew from carwow took it up Pikes Peak. But, rather than going all out and racing to the top of the hill, the crew does quite the opposite. They go downhill, trying to find out just how good the e-tron’s recuperation system is.

Their goal while descending the 156 turns and experiencing a change of elevation of almost 5,000 feet (1,524 meters) is to regain 10kWh of charge. The total length of the drive downhill is 12.42 kilometers or about 20 kilometers, but carwow seemingly talks about a driving distance of about 18 miles (30 kilometers). Nevertheless, it’s the regenerative power of the vehicle we’re interested in.

Throughout the whole run, the crew had an iPad with all the vehicle’s telemetry displayed, allowing them to better utilize the regenerative braking system. After the run, when they were stopped at the brake check facility at the bottom of the hill, the inspector couldn’t be more surprised by the low temperature of the e-tron’s brakes. This means that most of the braking was actually done by the regenerative braking system, and not the brake pads and discs.

However, to find out how much does the Audi e-tron actually manage to recharge while going down the hill, press play on the video above.

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26 Comments on "Watch As Audi E-Tron Gains Energy Downhill"

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Will they be calling this technology “Clean Electricity”?

There is a lot of confusion about the drive up/down Pikes Peak. The race distance is 12 miles, whilst the distance from the access gate to summit is 18 miles. The gate is at just under 7,800 ft, making the trip up just under 6,300 ft of climbing, whereas the race starts just after the lower downhill section (on travelling up the mountain) at 9,400′ providing the nearly 5,000′ of climbing. The brake check station is at Glen Cove which is at the 11,400′ mark and just under 7 miles from the summit.

(⌐■_■) Trollnonymous

Cool test. They should do this for all EV’s. Some peeps might be interested in the results.

I don’t feel like watching the video. Someone post a spoiler please?

I’m a little disappointed from the announced mass of the car (expected much better with current battery tech). But the regeneration seems really efficient and well calibrated. The fact that a little pressure on the brake pedal generates more regeneration before actually using the brakes is pretty good. And I hope the cameras replacing the rear view mirrors will be legalized in a lot of countries because it’s a really cool and efficient feature (better drag coefficient, smaller blind spot…).

It is efficient. 2600 kg * 1524 * 9.8 / 3600 gives 10.7 kWh

Is the amount of KWH the theoretical gain with no friction? Also the 1524 (meters?) should really be about 2000 (the 1524 is the race course 2000 for total peak to entrance station). Using 2000 the total potential gain is about 14 kwh meaning their friction losses are still only 4 kwh in 30 km. Does the mass figure used include the occupants of the car which are beneficial going downhill.

The mass includes the occupants as far as I know. The regenerative braking max power should be 220kW.

Yeah right. At what state of charge can the battery pack happily accept 220 kW?

Well, we know that it can happily accept 150kW till 80%, so I presume it’ll accept 220kW till 35%? Maybe 50%?

If 2600 kg is the correct mass it is superbly efficient. In fact I’m having trouble believing it. 93.5% efficiency just seems too good to be true, especially considering that his brake discs were at least a bit above ambient temperature (hence true efficiency was even higher than 93.5%).

Maybe it’s 2850 kg? And the start and end points didn’t exactly match the race, perhaps adding another 100 m of altitude delta? IDK, but these assumptions yield a still impressive, and to me more plausible, result of 80% efficiency. So clearly fairly small changes in the assumptions produce significant changes in the calculation.

See my note above; M. Kennel used the wrong elevation change. They gained back 10 kwh out of about 14 theoretical with no friction.

Your note is correct, they even said that the efficiency should be around 70%, which is anyway higher that practically any other EV.

I hope they’ve nailed the software though. A lot of EVs do this, even my first gen LEAF, but do it badly, resulting in inconsistent brake feel depending on SoC. (Obviously at high SoC you don’t get much regen, as it would damage the battery – unless you designed some burn system to waste the energy as heat, the only benefit of which would be to save mechanical brake wear (really just the pads, since the discs should last the life of an EV). Nobody bothers with that. But it means that to get a consistent brake feel software must engage hydraulic brakes earlier at high SoC. Nissan doesn’t, and you must simply push the pedal a little more to get any braking at high SoC. I don’t think this is a security issue, because any serious braking is way beyond the initial “bite point” in any case, but it’s definitely a minus point with the LEAF’s brakes, in my opinion.

I believe some large (non-EV) trucks actually have dedicated brake resistors, to reduce wear on the friction breaks?…

Even more important is this:

Fastned is saying that the e-tron quattro can charge at the max 150kW speed till around 80% on average, and that it charges with at least 50kW till 98%. That is completely unprecedented for any EV, charging at such high speeds to such high energies. And they have obviously seen it happen:

Another Euro point of view

So that would probably be one of the big differences between the eTron and the iPace probably, I mean the max charge rate.

Yes, absolutely. If my math is correct this means that it’ll take more or less 30 minutes to reach 80%, and then another 20 minutes to reach 98% if we consider from 80% to 98% a charge rate of 50kW (which is totally pessimistic, nearly impossible, since I do not expect the charge rate to fall immediately from 150kW to 50kW after 80%). But obviously you never start from actually 0. So if we consider as starting point let’s say 10% we get 26 minutes (for comparison it takes 40 minutes for a Tesla to do the same).

With a WLTP range of more than 400km (but let’s consider exactly 400km), it means you can get more than 320km of range in 30 minutes, and then another 72km in 20 minutes (again, very pessimistic). I can’t compare this to Tesla models unfortunately because none of its models have been tested with the WLTP procedure.

Isn’t 80% in 30 minutes in fact exactly what Audi claimed a while back?…

For the iPace in particular, see here:

The max charge rate should be 85kW, and the taper should start at 50%. The charge rate then goes below 50kW at 80%. With a battery of 90kWh this means that it’ll take around 32 minutes to get to 50% (from 0), or 25 minutes to 50% (from 10%) + another 32 minutes to 80% if we consider 50kW the average charge speed after 50% (again, very pessimistic).

With a WLTP range of 470km, this means you can get 235km of range in 32 minutes, and then another 141km in 32 minutes, and then we don’t know how much exactly for the rest.

This is amazing information, thank you very much! I had no idea this info was out there.

No problem, actually I was very happy when I found this info too. Fastned is really doing a good job at providing us with the info we need 😉

Audi did demonstrate charging at 150kW from 3-81% at the VW meet-up at the Wörthersee before. Sadly people around there are just ICE people so they didn’t even understand what sort of message that was.

Good to know, thanks. This means it is even more confirmed or at least probable that the actual e-tron will charge like that.

Kind of interesting experiment, but the guy is clearly an idiot! Not only does he not know the difference between power and energy, but he thinks a normal automatic doesn’t brake when coasting – most EVs lowest regen setting of course is DESIGNED to IMITATE the engine braking of a coasting ICE…

I do like having a zero-regen “sailing” option. It’s obviously the most efficient as long as only regenerative braking is used whenever you actually need to brake, since it eliminates unnecessary braking and ALL braking is wasteful.