Prototype Volvo Flywheel Tech Uses Car's Wasted Brake Energy 262
cartechboy (2660665) writes "Sometimes we get carried away with sexy moonshot car tech--whereas most everyday gains are about reducing inefficiencies, piece by piece. Volvo's flywheel energy-recovery prototype is a great example of the latter--not to mention similar to one used in Formula 1 racing. The system recaptures energy that would be wasted in braking, like a hybrid does, to reduce fuel consumption by up to 25 percent. When you hit the brakes, kinetic energy that's usually wasted as heat is transferred to a "Kinetic Energy Recovery System" mounted to the undriven axle. It spools up a carbon flywheel that turns at 60,000 rpm to store the energy. When the driver hits the gas, some of the stored energy is transferred back to power the wheels through a specially designed transmission, either boosting total power to the wheels or substituting for engine torque to cut fuel consumption."
Just like in Formula (Score:3, Insightful)
This seems great for high or nearly-sustained speed driving, but what I really want is an electric only option from 0-15 mph, a "parking garage" or "traffic jam" mode that I can put my car into.
energy from BRAKING - best for stop-and-go (Score:5, Informative)
It briefly stores energy from braking and uses it to accelerate a moment later. If you don't hit the brakes, it does nothing. If you hit the brakes and stay at a low speed for five minutes, it does nothing.
When it works is when you stop (which stores energy), then go (which uses the stored energy). In other words "stop and go" traffic is EXACTLY what this is designed for.
Re:energy from BRAKING - best for stop-and-go (Score:5, Funny)
That seems to make sense and seems like an interesting idea. Can you express it using a car analogy?
Re:energy from BRAKING - best for stop-and-go (Score:5, Interesting)
Actually, yes, I think we can, strangely.
Imagine you're coasting your way to the top of a hill and stopping at the top of it, with the brakes doing very little of the work in stopping you. By cresting to the top of the hill, we've effectively converted the kinetic energy you had into potential energy that can later be reclaimed when you go down the hill, and we've lost very little of that energy to heat from the brakes. That is, we can reclaim that stored energy to get a good chunk of the way back up to speed for a fraction of the fuel cost that it would have taken had that energy been lost.
In much the same way, a flywheel is capable of converting forward momentum into a form that can then be used later. You can think of it as an invisible incline under the car every time you hit the brakes, helping to bring you to a stop while storing that energy for later, and an invisible declination under the car every time you follow the braking with the accelerator, helping you get back up to speed without having to consume as much fuel.
(I'm now eagerly awaiting corrections, since I'm sure I misused terms and explained things poorly)
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Kinda, though I prefer my invisible hills analogy better. ;)
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For those who don't like hill analogies,
The flywheel works in the same way as putting your car into a lower gear and breaking against the engine.
You can picture it as the flywheel being separated from the axle (via a clutch) and when you apply the brakes it connects the flywheel up. You now have the inertia of the flywheel being overcome by the turning of the axle transferring the energy to the flywheel.
When you have stopped (when the system senses that the axle is no longer giving the flywheel any energy,
Re:energy from BRAKING - best for stop-and-go (Score:5, Informative)
1) Something like 90%+ efficient at converting physical energy into rotational and back out
2) Decided to use carbon fiber because instead of turning into shrapnel, it disintegrates when it smashes into its cage
3) Added less weight than an extra person
4) Was able to supply 80hp for 10 seconds at max
5) Was able to quickly and efficiently capture energy, so you could slam on the breaks and get your 80hp for 10 seconds very easily
6) Increased fuel efficiency for F1 racers by 10%-20% because of lots of hard breaking followed by hard acceleration.
I'm sure other safety issues will bring down the effectiveness of these devices for regular car users, but there is a lot of margin to make it an overall win.
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Isn't carbon-fiber dust incredibly bad for your lungs?
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They are not a myth.
Perhaps you should read and try to understand what you link.
Quote: Please note that only representative entries are considered
Most cars that use 3l or less fuel are sold in very low numbers, that is all.
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I know spritmonitor.de very well. They are one of very few sources of real fuel consumption data. Not silly test data that no one can achieve in practice.
Feel free to provide examples of in-production econoboxes with a 3l/100km fuel consumption under real-life driving conditions.
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My car is not a 3l car, but in city use, in summer, my Peugeot 307 uses below 3l. In the city, gear 5, rolling with 50km/h.
There are true 3l cars from Fiat and the Lupo from VW, should be easy to google for.
However the market share is irrelevant, hence they are not 'significant' and hence not listed on spritmonitor.de
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I my point invalid if I write 4l (essentially 60mpg) or 5l (~50mpg)?
I point at the moon-sized battlestations driving by, don't stare at my finger
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5l is doable in a petrol hybrid, and you can get quite close with certain non-hybrid petrol econoboxes.
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According to the article, it holds the energy for ~20 minutes.
Re:energy from BRAKING - best for stop-and-go (Score:4, Informative)
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If you are a careful driver and plan ahead to avoid quick braking, and also accelerate at a very modest rate your benefits would be small with this kind of system. It helps compensate for aggressive driving but it seems like it won't benefit drivers that already are trying to get good gas mileage.
Very true of highway driving, less so for stop and go city traffic.
Fuck Hypermilers (Score:5, Insightful)
Re: Fuck Hypermilers (Score:2)
Shouldn't you just leave a few moments earlier to catch the green wave then?
Fuck boy racers (Score:5, Insightful)
People who don't leave adequate braking distance and accelerate as hard as possible are the reason most of the traffic jams on my morning route occur. A single light touch on the brakes gets magnified into a ripple of progressively more urgent braking until you have traffic that grinds to a stop - no obstruction required. A few large gaps help to absorb this kind of thing and would keep the traffic flowing, but the few people who seem to think that tailgating people at beyond the speed limit until they give way and let the guy overtake you - so he can do the same thing to the next guy in the fast lane going the same speed - is acceptable make everyone else so paranoid that they are missing out on a particular piece of road that hardly anyone is willing to leave any space.
If everyone drove with a little more room, then the traffic wouldn't jam up so much, and paradoxically, people would get to their destination faster. The tailgaters are just spoiling their own driving party.
Re:Fuck boy racers (Score:4, Insightful)
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We'd still be complaining about the bottom 50%, but we'd be complaining to our domestic robots.
Re: Fuck boy racers (Score:3)
Scientific studies have shown the opposite though. People slowing down unnecessarily below average speeds is what causes traffic jams. Generally those that stand on the brakes the second someone in front taps off their cruise control with the brakes are the causes of the ripple effect.
Look at any section where lanes are reduced or split - people slow down (ok) but then there are those that slow down so much as to either fit in last minute that they slow down the entire side of the split that has less traffi
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Studies show that while aggressive drivers can cause traffic jams with their late braking, and may be your main problem, in general it is the timid drivers that cause the majority of traffic jams.
Leaving too much distance between cars, randomly braking, going excessively slow while merging and not capitalizing on turning lights all contribute to create huge interruptions in traffic flow. My personal favorite is the driver who watches crosswalk lights to try and predict the transitions from green to yellow
Re:Fuck Hypermilers (Score:5, Interesting)
Re:energy from BRAKING - best for stop-and-go (Score:4, Informative)
Not at all - if you hit the brakes at all you're throwing away kinetic energy as heat, no matter how aggressively or gently you do so. This system allows you to capture some of that energy instead and use it to accelerate again later. Unless you are in the habit of coasting to a stop without using the brakes or engine-braking at all this will reduce the associated energy waste.
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Accelerating at a modest rate is not particularly an advantage in a petrol car. Petrol cars are only decently efficient under full load, so you want to accelerate quite swiftly, using as high a gear as possible. If you are driving an automatic, it will spoil that idea by "helpfully" shifting down when it detects that you are pushing the accelerator, so that only works in a manual.
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Yep it won't help all 3 of those people in the world.
It will help everyone else.
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I live in a modest coastal city where the traffic is relatively sedate. My main problem avoiding unnecessary use of the break pedal is that so many traffic lights appear suddenly as you crest a hill or exit a swee
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2020?? (Score:2)
" “some form of KERS” would be inevitable on production cars after 2020."
I'm hoping that by then, electric cars (with regenerative braking) are starting to become the norm.
Really, 2020? With the pace technology develops, this might as well be Star Trek.
Gyroscopic precession (Score:4, Interesting)
Re: Gyroscopic precession (Score:4, Informative)
This was discussed when flywheel KERS was added to formula one. The forces involved are not significant, and on a heavy vehicle (as opposed to an F1 car) would have even less effects.
Ultimately it is just a stop gap. Electric is so much more flexible than the complex CVT and fundamentally limited flywheel used in this. Which is why F1 all went to battery based systems.
Re: Gyroscopic precession (Score:4, Informative)
The model demonstrated by Volvo has a horizontal axis, so the gyro forces will be greater and must be dealt with. Thankfully, it's pretty easy to quantify. If you get the flywheel spinning in the correct direction, you can even make the forces work in your favor to reduce roll during a turn.
Re:Gyroscopic precession (Score:5, Interesting)
The Chrysler Patriot prototype in the early 90's had this problem. This was a vehicle that was being designed for the 24 Hours of Lemans. It had a gas turbine that ran a alternator, which powered an electric motor driving the wheels. Instead of a battery pack it used a composite flywheel to store energy. Initially the flywheel caused too much of a gyroscopic effect and it was found that you couldn't turn the car. The solution was to make the flywheel gimbaled so it could rotate as needed while the car maneuvered.
http://www.allpar.com/model/patriot.html
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I would guess the effect would be very much smaller if it is mounted so it's rotating in the horizontal plane (vertical axis), than if it's mounted with a horizontal axis.
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going up or down a hill when you brake hard will be entertaining.... Mommy, why is that car standing on it's nose?
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Um.
You're going to get this effect (under braking or acceleration) no matter what orientation the flywheel is using. In one case it will be precession, in the other it will be a straightforward angular acceleration. The vertical axis might work better when your speed is constant.
When you apply the brakes with a vertical axis flywheel, you are accelerating that flywheel which means an application of torque. The frame of the car will experience the opposing torque, providing a twisting force in one directi
Brake Pedal (Score:4, Interesting)
I love this idea (and why has it taken so long to come to consumer cars), but please don't screw up the basic UI of a car the way some hybrids do! The brake pedal is for braking, dammit; simply lifting off the gas pedal should result in nearly coasting, unless I've deliberately put the car into a low gear for engine braking.
The hybrid I test drove (and I understand this is normal) would do regenerative braking up to the limits of that system on a simple lift-throttle, where the brake pedal was just the brakes. Talk about leaking the implementation details through to the UI! Don't do that!
For all I complain about UI designers, engineer-designed UIs are worse still.
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Engineer-designed UIs are damned near perfect. As long as you're the engineer that designed them. And it hasn't been too long since you used them.
Yes - I am an engineer. And yes, I have outsmarted myself more than once. Go back to a 3-year-old project and think, "What was this person thinking??? Oh wait, that person was me..."
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Engineer-designed UIs are damned near perfect. As long as you're the engineer that designed them. And it hasn't been too long since you used them.
Ain't it the truth! It's hard to tell from modern software, but you really can make a UI that's easy to learn without being expert-proof! But now the sad trend is to simply remove every seldom-used control entirely - I'm sure "UI designers" will eventually achieve the same degree of uselessness as an unfamiliar engineer-designed UI.
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I haven't seen this. My hybrid (Ford Fusion) bleeds a little off the speed when I lift the throttle, but somewhat less than a regular ICE drivetrain would. The brakes, on the other hand, extract speed energy into the battery as fast as the battery can take it -- if I'm braking harder than that, it simultaneously applies the friction brakes. From a "user interface" perspective, I can't tell which part of the brake system is being used until I've come to a stop, when it gives me a "braking score" that show
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That's a great design on Ford's part. They really have gotten their act together on most things (if only they'd stop with the deliberately-cheap interiors, a holdover from Mercury and Lincoln still being different brands instead of different trim levels).
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I don't know what model you drove, but my Fusion Hybrid does not behave that way. The only time it'll do regenerative braking without the brake pedal down is if its coasting downhill and would otherwise be gaining quite a bit of speed, and frankly in that situation I don't mind it applying a tiny bit of brake for me since I'd end up having to do it myself anyway.
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This is less likely to be due to mechanic performance limits but rather due hybrid drivers trying to optimize gas mileage via slow, smooth acceleration.
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This is specific to Priussies*. I drive a Camry Hybrid and have no problem at all getting up to 65 lickety split.
Before I got my car I considered buying a Prius but couldn't figure out if the car was gutless or the drivers were gutless. Either way, the Camry was a much better choice for me. And cheaper than a Prius.
*A Priussy being the driver of a Prius.
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What is annoying is the pulse and glide hypermiling thing... accelerating to 70, dropping to 55, repeating... supposedly is good for gas, but hoses traffic because of the speed changes.
The irony is -- it seems to be only Priuses. Camry hybrid drivers don't have that issue. Neither do the people driving the Lexus models that are hybrids. Neither do Ford hybrid drivers, nor the Insight/Civic drivers... it is just that one model of vehicle that seems to attract the people who tailgate the semis, pulse and g
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If you're in a cruising gear you don't get much engine braking, thus "nearly" coasting (and the bit further down my post about deliberately choosing a lower gear? yeah that bit). But you were only posting to call someone with a UID 10 years older than yours a "kid", weren't you? :p
None of which is really relevant for a hybrid. And of course the Tesla is a fixie.
mass in motion (Score:5, Interesting)
The big factor is mass. To store energy you need to spin up and down the mass. However to drive in general you want to carry less mass on the vehicle.
Factor #1: A more massive flywheel can store more energy at slower spin rates.
Factor #2: A more massive flywheel is going to be more of a load in general driving.
The optimium point of flywheel mass is going to depend on driving conditions. Really you should have at least 2 interchangeable fly wheels that you physically replace in the vehicle. One flywheel for city driving one for highway driving.
Factor #3: A spinning flywheel is one hell of an energy store. Having a stopped vehichle with a fully spun up flywheel hit could release the spinning flywheel to the detriment of pedestrians in the neighborhood.
Factor #4: Starting from a stop and attempting to corner, left or right, having a spinning flywheel is going to do gyroscopic things to the vehicle.
There are all sorts of tradeoffs and safety considerations here.
1) & 2) solved by 60,000 RPM (Score:4, Interesting)
It would seem to me that at 60,000 RPM, the rotational momentum is so much higher than the linear momentum that 1) and 2) aren't really a problem.
3 and 4, on the other hand, could be a problem.
ps consider toy car "friction motors" (Score:5, Insightful)
It occurs to that this is basically a larger copy of the "friction motor" that was used in toy cars. The ones you'd spin up by rolling them on the floor , then you let go and they speed away. If you ever played with those, you know that the spinning flywheel has WAY more than enough rotational energy than required to accelerate its own mass. Those aren't going nearly 60,000 RPM either. (I think, I've never measured their flywheel speed.)
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If the flywheel spins parallel to the road I don't think it would affect turning left or right - except it would resist the car leaning to the side on a sharp turn, which might be a good thing.
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... having a spinning flywheel is going to do gyroscopic things to the vehicle.
Isn't this usually addressed using counter-rotating flywheels? Or does that not apply to the issue here?
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Yeah, I'm not liking number 4 there.
If you you try to turn the flywheel around its vertical axis, it will try and twist around the horizontal axis, effectively trying to make the car roll over while it turns a corner.
The harder you brake coming in to a corner, the faster the flywheel spins, the slower you can take the corner.
It's also going to slow down the flywheel. That energy required to slow it down is going to come from the engine.
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We have formular one cars that run with 400km/h ... using fly wheels.
I assume the engineering challange to scale that down to 200km/h is done.
Hint, the company we right now talk about is Volvo, that should ring a bell.
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Not much sense having a separate flywheel for highway driving - highway driving involves minimal braking, and so offers minimal opportunity to recover energy while doing so. Energy recovery systems are targetted specifically at stop-and-go driving at reasonable speeds, even "mobile parking lots" rarely involve high enough speeds to offer much kinetic energy for recovery - the vast majority of wasted energy is in idling the engine without using it.
Re:mass in motion (Score:4, Insightful)
Counter-rotate the flywheels and #4 isn't an issue, no matter what the orientation is.
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Already been done: http://uploads.neatorama.com/wp-content/uploads/2010/09/Fred-Flintstone-Barney-Rubble-Car.jpg [neatorama.com]
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Adipose.
Already have the answer.
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We've been running them on french fry oil for years, so all you need to do is cook the average American car-driver down in a large stock pot and skim off the oil as it separates from the carcass.
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The mass of the flywheel is 13 pounds (~6 kg), while the whole device weighs 130 pounds (~60 kg). A lot of that is going to be shielding in case the rotor grenades.
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You do know that cars already have a flywheel in them...
at 1/20th the speed, squared (Score:2)
This flywheel is spinning at 60,000 RPM.
Energy = mass * velocity^2 if I remember correctly, so this flywheel has a like million times as much energy and therefore potential danger.
Engineers please feel free to correct me, or actually do the math.
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The problem is the "engineers" are trying to break laws of physics. the extra mass of the flywheel will soak up all the power gained from spinning it up.
A flywheel is Power Output = Power input - losses, You will not have any gains from the flywheel only losses. it will conserve some energy, but not as much as an electrical regeneration system does.
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"There are all sorts of tradeoffs and safety considerations here." /. is such a valuable resource for engineers the world over.
Thank you for your insightful comments. I am sure that the Volvo engineers haven't considered any of this and will be very grateful for your valuable input.
This is why
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It doesn't have to be at all heavy, the article mentions 6 kg. Remember that kinetic energy is proportional to the square of the velocity, so doubling rotational speed lets you cut weight by three quarters. Also, gyroscopic forces won't be a problem, you just mount the wheel horizontally.
Containing the stored energy in case of an accident likely requires some engineering thought, however. I suppose you would design the system so that it brakes the flywheel if it gets busted, converting the energy into heat
Safety issues? (Score:2)
So what happens when the flywheel shatters at high speed?
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No shatter. It's spun carbon fiber. You end up with a big bowl of carbon spaghetti.
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Same thing that happens when you spin a CD at 60,000rpm in a CDROM drive. It shatters into a million pieces and destroys anything delicate inside the drive.
You'll be fine if you're not in the car when it happens.
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Two thoughts:
1) How fast do your wheels spin now?
2) How often do they shatter?
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1) How fast do your wheels spin now?
Not very fast at all. Most engines turn less than 7,000 RPM and the wheels turn notably slower. The overdrive gear ratio will be just over 1, and the highest rear end ratios in common use are around 2.7:1. There's nothing whatsoever in most production cars which spins as fast as KERS.
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Turbo impeller.
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At 70 miles per hour a tire with a rim 15 inches wide will spin about 129 times per minute.
Call me when you invent a car that the wheels spin at 60,000 rpm, I want to watch you drive it.
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Call me when you invent a car that the wheels spin at 60,000 rpm, I want to watch you drive it.
I just invented one. It needs very smooth road though, for its tiny wheels.
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thousands of babies across the globe suddenly die in their sleep...
Waiting since the '90's (Score:2)
. . .for this to be in a production car. Back then, I read an article in Discover (?) Magazine about Mercedes working on this technology. Then nothing until today. Sounds great, to me.
Also a really interesting tech I read about at that time was smaller motors at the wheels. No need for transmissions and shafts and gears.
Pie in the sky tech I heard about then, too, was instead of brush and coil motors, having charged plate motors.
Still nothing on those last two.
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My father's been involved in alternative energy research since the 70's, I'm pretty sure I heard about regenerative braking with flywheels in the early 80s. (This is what happens when you're related to mad scientists whose idea of fun involves steam engines, solar panels and ocean thermal energy, preferably at the same time...)
Here's a patent filed in 81 and granted in 85 [google.ca].
This stuff is like clothing fashions, just wait long enough and they'll all come back, hopefully with the patents expired.
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When I was in school (mid 70s) there was work being done on "super-flywheels," both for automotive use and for fixed energy storage. Flywheels can deliver (or accept) virtually unlimited power -- not unlimited energy, but if you need a burst of power in a very short time, your limitation is not going to be the flywheel.
One of the applications I read about then was for a university particle accelerator. The local city got upset at having the lights dim all over the city when they fired it up, so they spent
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I also remember a same concept article talking about buses (mass transit) when I went to school (don't remember the magazine though).
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Also a really interesting tech I read about at that time was smaller motors at the wheels. No need for transmissions and shafts and gears.
Motors at the wheels are actually pretty lame, because they increase unsprung mass which negatively impacts handling. A motor for each wheel is a nice way to go, though. Modern CV shafts rarely fail until the boots do. Go inspect your CV shaft boots and have them replaced if they appear to be leaking.
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Brush and coil motors are old tech now. It's transistor and coil now
Probably Williams F1 Tech. (Score:4, Informative)
Williams F1 has been working on this technology for quite awhile now. It's definitely fascinating. This video shows [williamsf1.com] the technology applications.
Done over 50 years ago (Score:3)
This isn't a new idea. It's been tried several times since 1950 for city buses, which are constantly stopping and starting. In 2009, one was developed for use in London. In the 2009 model, the linkage to the flywheel is mechanical, through a continously variable transmission [torotrak.com], not electrical. Although this has been in test for several years now, it's only one bus.
That's the same technology Volvo is using. Putting this in a car seems marginal. It makes more sense for buses and delivery vans.
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http://articles.latimes.com/1997/nov/19/business/fi-55325
LoB
electric machines (Score:2)
I'd prefer air power (Score:2, Interesting)
This air-hybrid system [popsci.com] uses nitrogen, hydraulic fluid, a hydraulic motor, and a couple of high-pressure tanks. I imagine it shouldn't cost much more than this flywheel, and it should store energy much longer.
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Re:I'd prefer air power (Score:4, Interesting)
Compressing gas has a fairly lousy energy return. The air heats up when being compressed, and that heat is wasted unless you insulate the tank.
I love the complexity (Score:3)
This is why tesla, and I think Nissan, will become major players in the car making business.
Not Really - (Score:2, Interesting)
All Tesla proves is that it's easier and quite possibly cheaper to send payloads into space and back than it is to make a reliable, affordable electric car. Recall that Tesla and SpaceX were founded by the same guy.
Flywheels are old, old technology. They're very well understood and very reliable. Practically all of the gyroscopic problems can be resolved just by dividing the system into two wheels rotating in opposite directions - the forces cancel out. Mass producing sophisticated, relatively massive, vacu
Kinda like an old tractor (not) (Score:4, Interesting)
Early tractors had the power take-off geared directly to the final drive. So if you were using a big rotating implement like a mower which was driven by the PTO you needed to be very careful when you got to the end of the field because the mower had so much energy you had no chance of stopping the tractor with the brakes.
To get over that they added a coupler that would let the machine freewheel. I've been on a tractor without that coupler and it's pretty scary. Not stop and go, just go and keep going.
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Offtopic I know.
I'm still looking for something nice to say about Ford sense they sold their tractor division. Anybody?
Funny gyrations... (Score:2)
So what happens if you come to a stop and then want to turn right? You have a flywheel spinning real good and you're trying to change its axis. Either it's going to twist and bust its bearings and do considerable mayhem, or your car is going to go around the turn on two wheels. Fun times!
Prototype? (Score:2)
My 2005 Prius already have this technology as does many other hybrid vehicle.
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Mazda announced they're working on a hybrid system that feeds no energy directly from the engine and has no battery. It uses regenerative breaking purely to charge up capacitors which then power a motor used to add power to the drive train. It forgoes a lot of the weight inherent in the standard hybrid setup. I'm curious to see how well it'll work. It'd be awesome if you could plug it in to charge up your caps before you took off for the morning commute.