Ok, but it’s a good demonstration of how the simple act of closing a circuit increases braking power greatly.
It is actually closely related to how regenerative braking works. When a conductor moves through a magnetic field, a current is produced in the conductor and its motion is slowed. This is the basis for both a generator (including an alternator), such as is used in regenerative braking, and for the effect in the video (which incidentally is not actually the Hall effect; that’s something different).
BMW is actually looking at running a tiny steam turbine off the heat in the exhaust stream.
you will find that eddy current braking used on quiet exercise bikes and other places like roller coasters. the electricity doesn’t go anywhere it provides the braking.
Some technical info on the Prius MG1 and MG2
Brian
Another way that a hybrid can generate significant savings, at least in town, is by completely shutting down when stopped, for example at stop lights. My Insight does this. When the car is decelerating and the speed drops below a certain speed (I think it’s 7 mph) the engine shuts off. After stopping, the moment I start to let up on the brake the electric motor spins up the gas engine so that I can immediately pull out.
My Camry Hybrid does that and I always wondered why conventional cars don’t do that to save fuel. Does the ICE in a hybrid somehow take less gas to start up, so it’s worth it to shut it off for 60 seconds?
Start-stop systems are entering the mainstream. the difference is, with a Toyota/Ford style hybrid, the motors in the transaxle can start the ICE almost seamlessly, whereas with a non-hybrid start-stop car, the “start” portion is just like turning the key to crank the engine. I’ve driven a start-stop equipped Fusion and found it disconcerting, even though I knew the car had start-stop.
As I understand it, this can be done with hybrids because they have a powerful electric motor in the drive train that can be used to spin the gas engine to start it quickly enough that there’s no meaningful lag when starting back up. A conventional car would have to go through the normal process of using the starter.
There may be a way to design a conventional car to do this, but it seems like you would need the hybrid components to do it.
The diesel powered, manual, Minis do it.
When I drove my mother’s Prius, I observed that the gas engine shut off well before the car came to a stop (I tend to start decelerating much sooner than most people). This would be kind of impractical with a conventional ICE-only car, these days anyway, because shutting off the engine would affect the power brakes and steering.
Interesting. How much of a lag is there when it restarts? It better have a very reliable starter. You don’t want to be sitting at a stoplight in cold weather, cranking and trying to start. Although I guess modern cars do start pretty reliably.
I’m curious if you’ve encountered an issue I’ve encountered with my Insight. It seems to be a design issue rather than a problem with my particular car, since I’ve seen other people complaining about the same thing on an Insight forum.
What I’ve noticed is that, even though the restart is pretty much seamless and unnoticeable, there is sometimes a problem when I’m stopped on a grade facing uphill. When I take my foot off of the brake, there’s enough of a lag that the car will sometimes drift backwards a frightening amount before it catches and starts forward. There’s supposedly an anti-rollback mechanism but I suspect this is happening right at the edge of where the car makes the decision as to whether or not there’s enough of a grade to be concerned.
I’ve developed a habit for these situations where I first let up on the brake just enough for it to start the engine then immediately push back down and then, before it shutoffs again, I move over to the accelerator. This may sound like I’m slamming my foot up and down but it’s a subtle move that prevents the problem with no meaningful lag in starting. You learn where the sweet spot is that will just start the engine without totally disengaging the brakes.
short enough that by the time my foot moved from the brake to the gas pedal the engine was running and ready to go.
Aren’t you supposed to pull the handbrake on an incline? My friend didn’t know that, and he was driving a manual car. And he didn’t know how to drive a manual car. He managed to step on the gas and brake with 1 foot to move off.
not less complicated. More efficient at low RPM’s.
I always thought they should make a turbo-generator for hybrids to recover lost energy. Never heard of the BMW project. Sounds really cool and we’re just a year away from it.
It’s not a manual. I’ve never seen nor heard anything about using the handbrake on an incline with a hybrid.
The best electrical energy recovery systems work at about 30%. In fact, with a car like the Prius, the regen system doesn’t brake the car when the brakes are applied gently, and the mechanical brakes are used when a lot of braking energy is dissipated. Link
So like so much to do with EVs, the reality is nothing like as good as most are lead to believe. After all, the EV was tried a hundred years ago and with batteries for the energy store they failed to sell because of low range and the length of time take to ‘refuel’. The EV with an on-board ICE was unecessarily complex and heavy.
But politicians are encouraging EVs with financial carrots on the basis that they are somehow more environmentally friendly! Which they can plainly not be, unless you have a massive wind genny and a huge array of PV panels in your field. Batteries are the weak link - they cannot be recharged too quickly (hence regen braking limitations) and are so heavy that a lot of energy they store is used to accelerate them/the vehicle. The charger alone wastes 25% of the energy coming through the grid (which in itself wastes around 10% of generated power).
If you are interested in regen braking which is anywhere near efficient, then hydraulic hybrids are up to 85% efficient. UPS delivery vans are using a simple system to reduce fuel consumption hugely. link. A European car maker has a system on test with the idea of launch in a couple of years or so. Link
Umm you might want to go back and proof read your first paragraph.