Regen Suspension: Double Your Range? A Status Report (w/video)

MAY 11 2015 BY TDILLARD 42

In a recent story on CleanTechnica, author (and fellow Big Dig survivor) Daryl Elliott gives a great summary of the recent history of electromagnetic “regen” suspension, starting with the 2009 work at MIT reported by Green Car Congress. The story started a little earlier than that, actually, in 2001 or so with the work of two Tufts professors, (also reported in Green Car Congress) – Tufts Engineering Professor Emeritus Ronald Goldner and colleague Peter Zerigian within the School of Engineering, who received additional support from Argonne National Laboratory.

Goldner passed away around that time, and the company he helped to found, Electric Truck, LLC, has drifted into the ether, though still has a “live” website.  Our last contact with them was around 2009, and even then it seemed the company was fairly stagnant.  Enter the MIT work, then Levant Power, with a patent filing in 2014, but no appreciable site updates since 2012, and finally Intertronic Gresser and now we’re seeing claims of something like a regen suspension system enabling an EV to recover 100% of it’s battery-powered range.  That is, “…when the battery enables a ride range of,  for example 200 miles [322 km], you can drive round about 400 miles [644 km].” (…quote from Intertronic Gresser, via Elliot’s story.)  Um.  Hold on a second.  Let’s do some basic Physics, shall we?

Here’s their video (complete with snappy kind-of-funk B movie music):

Remember, now, you don’t get more energy out of a system than you put in, right?  This kinetic energy that our shocks are recovering…  where does it come from?  Simple.  From the vehicle’s motion.  Where does the vehicle’s motion come from?  The batteries.

Since the overwhelming bulk of the energy coming out of the batteries gets used in propelling the car, there’s simply no way you can harvest anything but a very small portion of that energy with any system…  kinetic suspension or otherwise.  For a company representative to say that in public?  Preposterous.  (While we’re at it, let’s mount a wind turbine to the roof and use that to charge the batteries.  That should give us almost unlimited range, right?)  Granted, as Elliot puts it, “…it became clear that their claim meant that 50% of the energy used to propel the vehicle would come from the electricity that their suspension system generates”, a little clearer than the 100% claim, still.  Our seat-of-the-pants engineering would guess about 2% of a vehicle’s energy is absorbed by the suspension, and only a fraction of that is recoverable.

Audi magnetic ride

Audi magnetic ride

But, while we’re on the subject, let’s look at where active suspension is these days.  While Audi and others are running various types of passive electromagnetic suspension, they’re (fascinatingly) using magnetic fields to change the damping characteristics of the hydraulic fluid in the shocks. What’s really interesting is that what looks like the first real electromagnetic active suspension was developed by the premier-audio company, Bose, way back in 2004, as we see in this Car and Driver story.  You can read all about it on the Bose site, but here’s a rundown from the Wikipedia:

Electromagnetic Recuperative:

Bose linear electromagnetic motor

Bose linear electromagnetic motor

This type of active suspension uses linear electromagnetic motors attached to each wheel. It provides extremely fast response, and allows regeneration of power consumed, by using the motors as generators. This nearly surmounts the issues of slow response times and high power consumption of hydraulic systems.

Electronically controlled active suspension system (ECASS) technology was patented by the University of Texas Center for Electromechanics in the 1990s and has been developed by L-3 Electronic Systems for use on military vehicles. The ECASS-equipped HMMWV exceeded the performance specifications for all performance evaluations in terms of absorbed power to the vehicle operator, stability and handling.

The Bose Corporation has a proof of concept model. The founder of Bose, Amar Bose has been working on exotic suspensions for many years while he worked as an MIT professor.

Here’s a good video put up by the Technische Universiteit Eindhoven guys showing how they use magnetic fields to anticipate and control ride.

So, we’re at an interesting place.  Electromagnetic suspension – both passive and active – is at a real-world state, and incorporated into existing cars because, well, it works swell.  Electric cars are becoming more widely used, and every available option to increase efficiency is being explored.  It seems only a matter of time before what’s available in suspension, in terms of kinetic losses, gets harvested…  but it’s a very small leak in a very big boat.  EVs generate (ouch) the demand, and the auto industry already has the tech foundation.  But keep in mind – “active” suspension, arguably the better-performing of the two, is just that, active.  It requires power, though it can recoup some of that power.  From Bose:

“The regenerative power amplifiers allow power to flow into the linear electromagnetic motor, and allow power to be returned from the motor. For example, when the Bose suspension encounters a pothole, power is used to extend the motor and isolate the vehicle’s occupants from the disturbance. On the far side of the pothole, the motor operates as a generator and returns power back through the amplifier.”

As far as the implications postulated in the CleanTechnica story?  User “Timo” on the Tesla forum may explain it best (ca 2011):

“Range is ratio of energy available – losses over time at given speed. Without losses you have infinite range. Major losses include ancillary, aerodynamic, drivetrain and rolling. This suspension energy gain is small part of the rolling resistance. Entire rolling resistance is about 1/5 of the losses car has at 60mph, so that alone already tells that that article is using imaginary numbers to make big news from nowhere.”

Categories: General


Leave a Reply

42 Comments on "Regen Suspension: Double Your Range? A Status Report (w/video)"

newest oldest most voted

Ted, thanks for your detailed science-plus-common-sense analysis here. Would that there was more of that on the Internet!

I could believe a 2% energy recovery, or just perhaps very slightly more. A claim for 50% is… an indication that somebody is either completely lacking in even a very basic understanding of physics, or else trying to promote a hoax. Both scenarios, unfortunately, seem to be pretty prevalent on the Internet.


It should be done like here on InsideEVs, good job guys.
What is kind of scary is how one of the largest clean tech blog/news site like CleanTechnica just published the article with little to none critical aspects.
It makes you wonder how large percentage of the rest of the articles are just crap and nonsense over there.


I am also rather amazed that CleanTechnia would publish these claims with only a mild caveat, and then proceed to spend much of the article speculating on the massive changes this would cause if it were true!

Sadly, it seems that we need to read future CleanTechnia articles with more than just a pinch of salt.

I see the author over there tried to backpedal when someone pointed out the reality in a comment: “Please note that I used heavy disclaimers in the article.” On the contrary, Mr. CleanTechnia author, you most definitely did not. Your disclaimer was entirely neutral: “Please note that CleanTechnica is not in any way validating or authenticating such a claim, we are only reporting information that is being communicated.” You also appeared to validate it in your opening paragraph: “This technology is expected to get to market…”

For a heavy disclaimer… well, no need to repeat what Ted Dillard wrote in the article above. He said it quite well.


When I see statements like those of Intertronic Gresser I know that marketeers and stock pumpers are in control,


I am going to touch my shocks and srings ater my commute home today. I hop I dont get third degree burns from all that heat energy they are soaking up. LOL

Alonso Perez

Exactly. I thought about this a few years ago and did exactly that. The shocks were warm, on a temperate but not warm day. However how much of that warmth was from the shocks themselves I don’t know, since the brakes are right next to them. And no, I did not touch the brake disk to find out.

Shocks don’t have heat sinks of any kind, or ventilation for heat dissipation. That’s all you need to know really. The ICE engine reveals its inefficiency because it needs a large, hot radiator at all times.

2% recovery sounds about right, on a bumpy road. On a smooth highway it’s probably more like 0.2%.


Worst thing is, a bumpy road costs you more in terms of efficiency/range than the regen makes up for.


And the extra mass of this fancy suspension system works against you at all times… especially on smooth roads where there is little to no recovery available. The weight alone would *reduce* your range in that use case scenario.


Sorry for all the typing errors. To used to spell check


“While we’re at it, let’s mount a wind turbine to the roof and use that to charge the batteries. That should give us almost unlimited range, right?”

I have seen people seriously suggesting that very thing, and at least one person who actually did mount propellers on a car and claimed it increased his range.

But anybody who thinks that’s actually possible is someone who, again, lacks an understanding of basic physics, including why perpetual motion doesn’t work in the real world.


They probably used a different universe for their calculations and forgot to mention it. 🙂


There will always be some perpetual motion scheme, although essentially, from our temporal perspective, the earth is a perpetual motion machine.

Even the Earth’s rotation is slowing every year.


Not that you’d notice. Besides nothing is perpetual, because nothing ever lasts for ever, though I suppose you could say that nothing is only thing that lasts forever.


Well, if it’s windy enough it’s possible. You don’t even need an engine – in fact it works much better without one.

Not very practical, though.


Well, at the risk of opening a can of worms…

Yes, you can harvest useful energy from the wind to propel a vehicle, so long as the vehicle is traveling at a fairly low speed, the wind is coming from the right direction, and the engineering of the windfoil (propeller or sail) and drivetrain are workable. The problem comes when you put propellers on a vehicle intended to run at highway speed, which is far faster than the wind speed. The propellers in that configuration cause a lot more wind resistance (wasted energy) than the relatively small amount of energy harvested. That’s why I compared it to perpetual motion; outside of extreme conditions (such as hurricane force winds), it would be getting more energy out than you put in if you could harvest net positive energy from wind on a car moving at highway speed.

OFF-OFF-TOPIC WARNING: If you’re really interested in prototype wind-powered “cars”, this is a very interesting site, altho it has nothing to do with electric vehicles or practical passenger cars. Caveat: this link goes to an archive at the Internet Wayback Machine, as apparently the website has been taken down:

good explanation on how it really works


Double your range? No way, that sound ridiculous. But even if it only boosts by 5 to 10 percent, it might be worth doing if it doesn’t cost too much.


For a tiny fraction of the cost, they could put full moon wheel covers, and rear fender skirts on, like 1950s hot rodders and current ecomodders, for as much gain.


For an offroad vehicle this might make sense.


I just like the idea of having shock absorbers which don’t wear out. 🙂

David Murray

It’s sad how many people don’t understand basic science. I still have people swear that they could attach a generator to an electric car so it could charge itself. After going round and round with them, I usually end the conversation by saying the following: “Great, go buy an EV and put your generator on there. You’ll be an overnight millionaire and solve all of the world’s energy problems that thousands of scientists and engineers have never been able to do. What’s stopping you?”


Next time, just point out that if that could work it would be perpetual motion, and that people have been trying to get that to work for centuries without success; then wish them good luck with another try. If they don’t understand why perpetual motion doesn’t work in our universe, then it’s probably impossible to explain to them why that won’t work.

(And don’t bring up the subject of regenerative braking; that will only give them more reason to think they’re right.)

Blind Guy

Hmm, I wonder if the Bose active suspension system would work well enough to tame unsprung weight of in-wheel motors? I don’t see the Bose system ever payig for itself with regen but I am surprised I haven’t read about it being used in some luxury or specialty vehicles.
In concept, the Bose system could raise a vehicle if a driver had a button to press when there might be debris in your lane suddenly and the best option might be to rise above it. Even better, add it to a safety system.

Jay Donnaway

fuggedabout the miniscule energy recovery- I want these puppies to be reversible. No longer will my homies need fancy hydraulics to get the front end jumping, just buy an EV with regenerative shocks and wire ’em up for manual launch!
It amazes me when companies chase a cost/benefit equation uphill when there are niche markets that’ll pay a pretty penny to be beta testers for you.


Strange enough, I know one very articulated people who are fan of those.
Truth is, he also fantasized about everything being big oil plot and perpetual motion.
Seriously, 2% recovery?
I bet for 2% loss at best and a substantial upcost that most would’t want to pay.
But the upside is that you have active suspension and this alone might worth it.

John Hansen

I don’t think that you could get 50% more range from this, but I do wonder what percentage of total energy is lost to absorbing bumps in the road. It’s probably considerable. Consider if you were pushing a heavy wheel barrel across a bumpy lawn compared to pushing it down a paved sidewalk. It probably takes at least double the energy to push it across the lawn. All that extra energy is being absorbed by the bumps. In a car you have braking, wind resistance, tire resistance, parasitic losses (headlights, AC, etc), and bumps in the road. I really wonder how much of the total energy loss (energy not put into forward motion) is absorbed by the bumps compared to those other factors. Again, it’s probably not 50% (on most roads), but it’s probably considerable.


No so much.
The energy absord by the bump is store in the shock an release when the wheel is push back in place, less what is loss in heat in the shock by the differential of power by the bump and the slower pusback.
This energy loss is impairing the motion of the vehicule.
If you were a good cyclist you would know that no one is able to go as fast on bumby road than on a flat mirror like road.
It’s not just a question of comfort, but your effort is transmitted so much better when the tire stay on the road.
Energy= nothin is created, nothing is lost!


I guess a lost a “g”!


The mass of the electrons from the missing “g” has been converted to energy in the form of confusion in the mind of the reader. 😉


Or did you just create a “g”?


I wonder how much gravity contributes to the energy recovered, since a bump that pushes the car up will cause it to fall due to the pull of gravity.


The only way to get gravity to perform useful work is by a net movement of mass downward; for example, as in using falling water to turn a turbine.

A wheel bouncing up and down on a rough road is just an oscillating motion; no net downward movement. Therefore, no net energy gain or useful work performed.


I think the study was done driving in Washington DC, the city streets here can generate zillions of watts of energy like a third world city. :/

Bill Howland

Since so many cars have this ‘magnetic suspension’, including the more upscale GM cars and trucks, I wonder what the average and peak power consumption of these systems is from the vehicle’s 12 volt system.

I also wonder the same thing with electric power steering which most ev’s have. Difficult to find accurate information.

An active suspension applied on the Model S, if it saves 2%, would increase the range with an extra 5 miles. The university of Eindhoven, just near Tesla’s Tilburg factory, electromagnetic suspension system is interesting because it combines a spring and the magnetic system. It appears as being directly adaptable to an existing car and it also has the merit of bringing a new development away from the Bose seemingly stalled situation. It would be very interesting if Tesla could provide the university of Eindhoven a Model S as test car to integrate their suspension system in it and just see how much effect there really is on range and ride comfort. Apart from comfort, it is also the only system that could save a wheel from a pothole and that is worth a lot when you have experience a sudden breakdown from driving in one on a freeway in a late evening. Of course, as with any new technology, the price would be high in the beginning but would decrease quiet fast later on and with standardized mass production. For the Model S, aside from the range increase, better comfort and pothole safety, it would also further enhance the… Read more »

The heavier the vehicle and the more suspension travel and the higher the speeds, the more it will recover. I think 2% recovery may be underestimating it in some applications. The most extreme example would be off-road racing.


And here I was thinking that gravity exists. 😛


Ok, I’m lost. So this means my engine (yes yes, no Ev unfortunately) needs to work double if the road has a few bumps? I mean, if the road was flat like ice my car would be able to reach 300 kmh with no effort? What exactly are they saying? Anyway, I stopped reading cleantechnica because of stuff like this. And then I found you guys and I’m happy.


If you have ever ridden any distance on a bicycle, you understand the effect of bumps intuitively. Riding on chip seal roads is much harder than riding on smooth hot pack asphalt or concrete. A bump is a very small hill. One of the advantages of pneumatic tires is that they act as suspension. Only a fraction of an inch of travel, but the difference between solid rubber tires, and pneumatics is huge. An actual suspension does the same thing for bigger road irregularities. Instead of the entire mass of the car having to climb the bump, only the unsprung parts need to.