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Comment by JeffL | Hacker News Reader

I believe that if people drove exactly the samemas before, they wouldn't get full benefit of regen, but I don't believe people will drive the same as before. I know I don't. Driving without ever using the brakes in my Model 3 is smoother and a bit of a fun mini game. One quickly learns not to accelerate quite as much when there's a visible red light ahead and how much the Regen brakes will slow the car down.

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I find my experience to be exactly the same with the couple EVs I've owned. You very quickly adapt to learning exactly when you need to let off the accelerator, and even going from EV-to-EV where the regen curve is different, it only takes a couple tries to adapt to the new vehicle again.

The e-Pedal in the Nissan Leaf is wonderful, if you lift your foot off of the accelerator completely the car will apply optimal regen until the car stops.

Its really freeing not to have to look at the regen gauge at all, I just keep my foot over the brake pedal just in case I need to stop quicker than the regen braking.

What if you’re going down a slight decline where you could normally coast and maintain your speed. Do you have to leave your foot on the pedal and waste battery?

It's not wasting battery if you have your pedal in the position where it's coasting, neither regenerating nor accelerating.

If you want to coast, you have to apply slight pressure to the accelerator. It doesn't use battery. It's a little weird at first, but you get used to it in a couple days, then it's second nature.

Its really intuitive, if you are going a little too fast you just let up the pressure on the pedal. You don't have to think about if it needs to use battery, regen or coast to maintain the speed you want. In that aspect its like using cruise control in other hybrids/ev.

I don't think commercial drivers are going to be paying attention to regen rates as they are trying to make 300 deliveries on their daily run.

For personal vehicles it makes a lot more sense, particularly when you realize using regen braking means less brake and battery wear so it helps lower maintenance. I do similar things with the fuel economy gauge in my car.

Good insight -- the incentives are on maximizing number of deliveries per unit time. I certainly hear (and sometime even see) UPS drivers gunning their giant diesel vans down my street only to hit a stop sign every block.

So the interesting question is can operating costs make their way into the incentive structure (theoretically it should be able to with good vehicle telemetry).

Whether it's worth it or not to adopt that incentive structure is another question: is the cost of fuel and maintenance greater or less than the marginal revenue from each additional package? Because you're right, currently the incentives are infamous for maximizing number of deliveries. However, the famous UPS-minimize-left-turns routing optimization story suggests operating costs do factor in as well.

> So the interesting question is can operating costs make their way into the incentive structure.

It would likely be easier to just increase vehicle efficiency in the form of better braking, lighter vehicles, higher battery density, etc.

a supercapacitor could suck up all that sudden power and send it right back out to get the vehicle moving again.

Say a 0-60 start needs 20KW for 10 seconds. That’s 200,000 joules? How far away are we from a set of capacitors that can store that?

The more interesting use case for supercaps is in the 60-0 case or in the case of delivery trucks, 30 or 15 to 0. The inefficiency is in capturing the braking energy. If you can use supercaps to capture this inrush then you can trickle it back in to the battery pack. You don't need the capacity to capture all the braking energy nor do you need supercaps to replace the battery. You just need enough buffer to improve your overall efficiency. In something like a delivery truck the battery/cap ratio could even be adjusted with modular packs depending on route. I'm imagining something similar to what Gogoro scooters use but with two kinds of pack.

0.5 * 1850 kg * ((60 mph)^2) = 665 483.056 joules

Supercaps are 28800 Joules per liter, so you'd be needing nearly 700 liters of them to store the energy of the car decelerating from 60 mph once.

700 liters is a lot of volume in a car where you already use a lot of the available volume for batteries - it's more than the trunk and frunk combined on a Model3.

That might still be doable for a delivrry van or a bus, even if it is heavier. Natural gas powered already have quite a big "hump" on top for the pressure botzles with gas, I could imagine putting the supercaps there and the regular batteries inside the chasis to keep the center of gravity low.

0-60 certainly is not the important metric for this application, perhaps aside from rural routes. Most residential delivery, you're maxing out at 30mph.

Correct, and given that the velocity is squared in the energy equation, this is an enormous difference.

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