Are you sure brakes go on the list? Regenerative braking uses the motor, not brake pads. The track record of this approach is already proven in cars.
According to the article, most commonly these are not used for regenerative braking, the energy is wasted as heat instead.
Eddy current brakes can be used for regenerative braking if there's an electric drive train (and high power electronics to handle it) but more typically the energy is just wasted as heat in a cooled resistor grid.
Mechanical/hydraulic braking can be used to spool up a flywheel and this was used in Formula 1 in late 2000's (now they use electrical regenerative braking instead).
Which of these techniques is commonly used in trucks?
https://en.wikipedia.org/wiki/Retarder_(mechanical_engineeri...
Originally, it is right that retarders were introduced to just having a non-destructive brake by just wasting the energy. That was around the 1980s. This was just to save maintenance cost as brakes were a big part of that costs.
The trucking industry is about costs and every little penny you can safe. So, years ago it started: Why do we waste that energy and do not re-charge the battery with that, because that reduces load from the generator and that will reduces fuel consumption?
Retarders have a huge impact in costs when your are counting miles. Retarders are having the disadvantage you can't brake to full stop with them. That's why they never worked in cars, because they are always additional to conventional brakes. So they add complexity and weight, both of which you want to reduce in cars.
Is the energy from braking really so small that it can't even fully charge the starter battery?
Honest questions. I figured that since regenerative braking in cars seems to double fuel efficiency, that order of half the power used to accelerate was recovered and I would have thought that was a very large amount of power to store.
Or is it because of the nature of long-haul trips? I know hybrids have much less advantage on the highway, maybe for long-haul trips the ratio of energy lost as air friction to energy lost in braking is vastly different.
It is always the question of what type of truck you are running. Do you just have storage goods, or do you have goods that need refrigeration? In the later you need energy to power that. As your truck does not know in advance what kind of trailer will be towed (connected, what is the right word?) the truck needs to be prepared.
Yes, extra power is dumped. But that is true for any kind of vehicle.
> Or is it because of the nature of long-haul trips? I know hybrids have much less advantage on the highway, maybe for long-haul trips the ratio of energy lost as air friction to energy lost in braking is vastly different.
Actually, Hybrid is very good concept for long-haul. Because on highways you can do coasting (sailing as we say in German) very efficient when you are in cruise control. Because with all the little hills up and down at the same speed, hybrid takes its full advantage.
I believe the normal way to handle this scenario is to just fall back to mechanical braking.
Potential energy lost by a truck going 10 m (vertically) downhill: 40 000 kg * g * 10 m = 4e6 J.
Capacity of car starter battery: 40 Ah * 12V = 400 Wh = 1e6 J. Let's guess a truck battery has 4 times the capacity of a car battery, so 4e6 J to full charge.
That's just down one small hill and all subsequent braking energy for the entire trip is wasted.
https://arstechnica.com/cars/2017/09/this-cement-quarry-dump...
(I don't think you would call a vehicle with mechanical KERS system a "hybrid", although it technically is as there are multiple propulsion systems in the vehicle.)
(Just being pedantic)
Design and maintenance procedure remains the same, maintenance interval drastically increased.