Build Your Own Hybrid-Electric Car?

BlueJay465 writes "On almost every news outlet, everyone is talking about the price of oil, both foreign and domestic. This sent me to do some research on what it would take to keep the investment in my current vehicle, while getting the added benefits of hybrid-electric technology at the lowest price. One company, Sigma Automotive, has already jumped on that bandwagon, and will soon be offering a kit for your car engine that will boost performance and increase fuel-economy by adding all the extra electronics, hardware and capacity (avail. Q3-Q4 2004). My question is, how much would it cost to really 'Do It Yourself' using off-the-shelf parts?"

Comments

Seems legit to me

[YankeeInExile]

I read through their site, and while I am vaguely skeptical of things like the lifespan of the Super Capacitor Battery Pack and I2R losses system wide the basic theory is sound.

It seems like the product right now is targetted at people who want an extra 35 b.h.p. "off the line". And if you do a lot of stop-and-go driving, that could help a lot.

In my gut, I think a fully electrical transmission would provide better systemic efficiency, but that would be nowhere near a bolt-on system. (I base that on: the specific consumption of any I.C. engine is lowest when it is near it's peak output. Any system that is predicated on running the engine at variable speed (i.e. using a traditional mechanical transmission) is going to, by necessity, run the engine most of the time away from it's peak efficiency. I would be willing to hear the argument that the gain of running the engine at peak efficiency would be offset by the losses in the motor-generator pair. (If so, why has it been the standard technology in railway traction for over fifty years?)

Re:Seems legit to me

[Waffle Iron]

I would be willing to hear the argument that the gain of running the engine at peak efficiency would be offset by the losses in the motor-generator pair. (If so, why has it been the standard technology in railway traction for over fifty years?)

I could hazard some guesses about why we don't currently see electrical transmissions in cars:

Weight: It seems to me that a motor/generator pair would probably weigh more than a mechanical transmission, which is just a few gears and/or hollow turbines. This isn't an issue on a locomotive, where heavier is better for creating traction (IIRC, some of the biggest steam locomotives weighed as much as a 747).

Power: A lot of people are used to having 300hp on tap. That's almost 1/4 of a megawatt. You'd need to have some serious power control circuits to handle that much juice. A locomotive is powerful, but pulling a train is really more about torque than raw horsepower. Electric drives do have excellent torque capabilities (and it's just about the only technology besides steam pistons with enough torque to start a freight train), but people in cars want neck-snapping acceleration. That would require a lot of copper and power controls.

CVT: Continuously variable mechanical transmissions have already been on the market for a few years. I would imagine that they can keep the engine running at a fairly constant rate. I think that they are somewhat more efficient than standard transmissions, but not by a huge factor. What makes hybrids special is that the engine produces almost constant power, not just speed, because it uses the batteries for power storage when it is generating a surplus. This allows for much more efficient operation than just a CVT. It's interesting that some of the hybrids use a mechanical transmission in addition to the electrical boost. I gather that that's because the mechanical drive was more cost-effective for transmitting that portion of the total power.

Re:Just a guess

[YankeeInExile]

Not bad ... in their own site they suggest MSRP should be +/- 2800.

Q. How much does the Electrocharger(TM) cost?

A. Estimated retail is $2800.00 USD.

Devil in the system

[Billy the Mountain]

It may not be too prevalent in electric motors, but there's a demon that lives in power transmissions, especially where shafts are involved. It's called tortional vibration. It's a close relative to harmonic vibration of the type that tears poorly designed bridges down in heavy winds. Automotive companies are able to tweak a design until all or most of the tortional vibration is ironed out, then they mass produce. Building a one-off unit, you'll have to resolve these issues, as they may crop up, on your own.

BTM

Re:Devil in the system

[deacon]

The vibrations come from using a toothed rubber belt (gimler belt, which is springy or elastic) to join two inertias or masses (the crankshaft and the new alternator/generator thingy.

Since the engine output is pulsed (a pulse happens with every power stroke) there is a ready supply of driving or excitation vibration which is just waiting to find the resonant frequency of the whole system.

And since the pulse frequency varies with the engine speed, you have a full range of driving frequencies to work with.

If the resonant frequency of the engine/gimler-belt/alternator system is outside the driving frequencies caused by the engine, everything is fine.

If not, the forces in the belt can become "Large"

:)

Re:BUILD?

[DaChesserCat]

Remove the main pulley on the engine, and replace it with a special toothed one for this rig. Remove the alternator. Hell, remove the starter while you're at it. Put the special bracket on the engine. Mount the Integrated Starter Generator (the term has been around long before this product was announced) on the bracket. Use the toothed belt to connect the ISG to the main pulley. Mount the electronics box and connect it to the whole thing. Congratulations: you now have what's known as a light hybrid vehicle. The ISG can provide regenerative braking and off-the-line torque. Technically, you can kill the engine while you're sitting at the light, and the ISG has enough horsepower to spin the engine to operating speed (roll-starting it, essentially) and get you started off the line.

Ford has been playing with a prototype system similar to this. They got about 15% improvement in fuel economy. Considering the increased costs involved, they decided it wasn't worth it. Not for a measly 3-4 MPG on an Escape. For an Excursion, you're talking 1-2 more MPG.

Don't get me wrong; this helps. Just not as much as you might hope. It's a good step in the right direction, in an attempt to help reduce the fuel consumption of existing vehicles. And, as they mention, since there are NO internal modifications to the engine, it's a bolt-on accessory which your typical shade-tree mechanic could probably install on a Saturday.

Transmission woes.

[Pyro226]

The transmission would be one of the hardest things to deal with. You want the gasoline engine to be at a peak efficiency RPM as much as possible. The best way to do this in a hybrid car is to have the electric motor generate electricity when spinning the engine at an efficient RPM would provide too much acceleration, and use electricity when an efficient engine RPM isn't enough acceleration.

The toyata prius has a very special system that deals with this, as this page shows. Especially with hybrid SUV's coming out soon, building your own hybrid seems like it would be way too much work.

Also keep in mind, that right now making a hybrid car (for a major automanufacturer) costs several thousand dollars more than making an equivalent conventional car mostly because they don't have enough mass production on the hybrid parts, and they are making thousands and thousands of cars. Buying the parts individually, the price would be outragous.

Don't try this on your leased car.

[huchida]

I'm not sure, but something tells me this will void the warranty.

How about brew-your-own alternative fuel?

[Tehrasha]

Local boy here tried that route. Was making all of his own bio-deisel by recycling/converting waste deep-frier oil from the local resturaunt chains. Made the newspaper, was praised up and down for being thinking outside the box, was really cool....

Now the state govt. has stepped in and want him to pay state fuel tax on the fuel what he makes and uses himself....

If he were making it and selling it to others, I could see their point...but jeez!

Re:News outlets

[defishguy]

Yes, and my computer tends to run faster when I'm wearing a blue shirt too. Our "war" didn't do one thing either for or against our allies economies... they were tanking right along with ours because of a certain .com bubble a few years back. Oh and the oil prices? Speculators in the American market bid up the oil when it looked as though the S. Arabian monarchy was in political trouble. It was AMERICAN investors that caused our oil spike by creating an artificial demand for crude, by speculating on further price increases (which didn't happen). There isn't and hasn't been a decrease in world oil supplies, just an increase in those wishing to purchase some of it. If you want to have a political agenda please do so, but do not disguise your feelings about the war in Iraq by complaining about oil prices. They aren't connected.

Pretty foolish

[duffbeer703]

The return seems pretty slim for the amount of hassle and cost that you will put yourself through. Making huge powertrain and weight modifications to your car will likely have unexpected and bad consequences, which you will be on your own to fix.

IMHO, if you are truly economically sensitive to gas prices, I suggest that you buy a '94 or '95 Toyota Tercel/Corolla, Ford Escort or Honda Civic. You'll easily get 35-45mpg with these cars and spend a grand total of $3-5k for the whole vehicle.

If you want to make a statement about "saving" the environment, move closer to work.

Guaranteed easiest way to make your car hybrid

[britneys 9th husband]

1. Remove the gas cap.
2. Move remainder of car off the driveway.
3. Attach a Toyota Prius or Civic Hybrid to the gas cap.

Seriously, it seems like it would be very difficult and expensive to make this work, and even if you did somehow succeed, most states would require you to get the car smogged or otherwise inspected, which could prove difficult after such extensive modifications. If you want an inexpensive hybrid, I suggest a 2001 or 2002 model Prius. They're cheap because everyone wants the 2004 model.

Regenerative breaking...

[the_rajah]

has nothing to do with the mechanical brakes other than that it takes some of the load off them.

Remember that any DC motor can work equally well as a generator. In regenerative braking, the motor becomes a generator providing mechanical resistance to slow the vehicle and the energy produced is fed to the energy storage device, either batteries or super capacitor where it can later be recovered and used over.

Actually this is fairly common practice in certain types of traction (cabled) elevators where the motion of the elevator car, say, up in the case of an empty cab with counter-weights heavier than the cab, actually pushes power back into the 3 phase power lines. There are no big resistors needed to consume the energy produced when the drive motor becomes a generator. This is efficient in terms of energy consumption.

Mechanical brakes on elevators are normally set only after the cab is electrically stopped and held at floor level.

"Do the Right Thing. It will gratify some people and astound the rest." - Mark Twain

Re:Seems legit to me - railroads

[psetzer]

Well, let's take a look at what we're talking about. Suppose we're trying to push an SD70MAC, which produces 6000 hp at around 1800 RPM. First things first, if you want a manual transmission, this involves the mother of all clutches. Otherwise, it involves the mother of all torque converters and a truly massive set of planetary gears. Neither is very pretty. Next up, you have to get the power to what can be at least sixteen drive wheels. Oh, and they're on pivoting bogies in some cases, which makes drive shafts much more fun. Finally, you have to have an engine with a wide powerband, and the engine won't spend most of its time running most efficiently. This is because in a manual transmission, the wheels rotate at a constant multiple of the rotation rate of the engine. If the wheels are stopped, so is the engine, unless you're depressing the clutch.

The reason for having electric drive is simple once you realize the previous facts. First, there's simply a direct shaft from the engine to the alternator or generator (Trains can be both AC and DC). That means no gears at all, and no clutch or torque converter. The wires from our generator can run to the drive motors in any manner that they wish. Finally, they connect to the wheels directly, with no gearing. Note that the speed that the engine is turning is completely independent of the speed of the wheels. This allows improved efficiency, and it lets you have any torque at zero velocity. Furthermore, note that we also have maximum torque starting out, and trains really need it when someone decides to save money by putting fewer engines on a larger consist. Even though it suffers from all the inefficiency of the two conversions, it can always run at the engine's sweet spot. However, the fuel efficiency isn't as big of a problem as it seems. Once a train is rolling, they need very little power to keep it going. The fuel that is used in the engines is also not the kind of stuff that you would put in your car, or your tractor for that matter. It's like high-sulfur 30 weight, and it costs less than any other petroleum product short of road tar.