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Any vehicle is a hybrid when it combines two or more sources of power. Hybrid cars run off a rechargeable battery and gasoline.
Hybrid engines are built smaller to accommodate the 99% of time when not going up hill or
accelerating quickly. It uses the battery to provide extra acceleration power when needed.
When the car is stopped, hybrid gasoline motors can shut off and run off their electric motor and battery.
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Hybrid cars are often lighter and more aerodynamic; tires are often stiffer and inflated higher to
reduce drag.
Hybrid cars often recover braking energy and use it to charge the battery; no plug-in or long extension
cords necessary.
How Hybrids Work: Animation (fueleconomy.gov)
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Full Hybrid is often used when the vehicle can move forward at low speeds without consuming any gasoline. The Toyota Prius and the Ford Escape hybrid can do this. The Honda hybrids and the GM trucks can't.
Mild hybrid cars move from a standstill only if the internal combustion engine is engaged, and use the electic motor primarily to assist the gas engine when extra power is needed.Both full and mild hybrids require use of the gas engine when reaching higher speeds (of about 20 – 25 mph or more.)
Mild hybrid systems can broken down into subcategories:
The Stop/Start hybrid system, used on GM trucks for example, shuts the engine off when it would otherwise idle and restarts it instantly on demand.
The Integrated Starter Alternator with Damping (ISAD) hybrid system allows the electric motors to help move the vehicle in addition to providing stop/start capability.
The Integrated Motor Assist (IMA) hybrid system is similar to the ISAD but has a larger electric motor and more electricity can be used to help move the vehicle.
Some technical consultants , includes the Honda system in the list of full hybrids, based on its voltage level, electrical energy storage on board, and regen braking capacity. Dave feels that that the Chevy truck is the only real mild hybrid system presently on the market. Dave says, “Most mild hybrids are start/stop units,” referring to capability for hybrids to slip into electric mode when coming to a stop, rather than idling.
In other words, the fullness or mildness of a hybrid is a contiuum, not an absolute. The goal is to use every means possible to increase the efficiency and performance of the car, while relying on the gasoline internal combustion engine as little as possible. The degree to which the vehicle uses its electric power sources, or reduces resistance or weight for that matter, is the degree of its “fullness” as a hybrid.
Parallel versus Series Hybrid.
If the fullness and mildness dichotomy is confusing to you, then the parallel versus series definitions will be impossible and/or contentious. Let’s keep it simple, and allow the debate over terms to take place in our discussion forum.
In a parallel hybrid, the fuel tank supplies gasoline to the engine, while at the same time, a set of batteries supplies power to an electric motor. Both the electric motor and the gas engine can provide propulsion power. By contrast, in a series hybrid, the gasoline engine turns a generator, and the generator can either charge the batteries or power an electric motor that drives the transmission. Thus, the gasoline engine never directly powers the vehicle. Today’s hybrids are all parallel hybrids, although some would argue that the Prius has characteristics of a parallel and a series hybrid.
Plug-in Hybrids: Pushing the Envelop:
Just when the American public is finally starting to understand that you don’t have to plug hybrid cars in, here comes the plug-in hybrid. With the plug-in hybrid, you still will not be required to plug the car in, but you’ll have the option. As a result, drivers will get all the benefits of an electric car, without the biggest drawback: limited range. You'll be able to go all-electric for the ninety percent of your driving which takes place close to home. When the electric charge runs out, a downsized gas engine kicks in.
Most hybrid car drivers (including me) do everything we can to keep the car in all-electric “stealth” mode. Prius and Escape drivers can keep this going when the car is in slow stop-and-go traffic. Plug-in’s would extend the stealth mode for the lion’s share of our local driving.
A hybrid gets about twice the fuel economy of a conventional car
A plug-in hybrid will get about twice the fuel economy of a hybrid
What are the naysayers saying about plug-in hybrids? And how do plug-in advocates respond?
The extra batteries will weigh too much.
Response: The extra weight of the batteries will be offset by the reduced weight of the gas engine. Combined gas-electric horsepower will be greater than the gas engine alone.
The extra batteries will cost too much.
Response: New, more powerful and cheaper NiMH batteries will keep additional costs to only 10-15% above today’s hybrids. Recharging could take place during cheaper off-peak hours. Total operational costs would be one-sixth of gas cars.
Producing power from the grid (to charge the cars) will produce additional emissions.
Response:
The power industry is already shifting to cleaner fuels, like natural gas, to power the grid. (For most commuters, the car would generate no local emissions).
Additional Benefit: Vehicle-to-Grid Power
The larger battery packs used in plug-in hybrids could juggle power back and forth from the car to your household current. If adopted on a widespread basis, a fleet of plug-in (a.k.a. "gridable" hybrids) could supply power back to the collective electric power grid. Individual car owners would be compensated as much as two to three thousand dollars per year for the use of their energy storage capacity—offsetting their purchase and operating costs.
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Quiet beginning:
Step into a hybrid car, and turn the ignition. The first thing you notice is how much quieter it is than a conventional car. If you are in a Prius, at this point, the car’s electric generator/starter silently cranks up the internal combustion engine (ICE). As soon as the ICE is warmed up, it automatically shuts off. The Prius electric motor is now online, while the traditional gasoline engine remains dormant until needed.
The Prius will stay in this all-electric mode until about 15 mph. If you stay at low speeds, you are effectively driving an electric car, with no gas being used, and no emissions from the tailpipe. Pretty cool. The more spirited driver will cause the ICE to kick in at lower speeds.
Unlike the Prius, the Honda Insight and Civic internal combustion engines warm up and then shut down after your first stop. This “idle stop” feature goes away when you lift your foot off the brake pedal, shift into gear, or push on the gas pedal. The Honda has more modes because it has two types of transmissions, a standard shift and a CVT. Depending on how hard you step on the gas pedal, the car’s computer will determine how much power to draw from the ICE, and how much extra power to pull from the car’s electric motor. The dashboard shows you exactly when the electric “assist” is working. After moving forward and then coming to a stop, the ICE shuts off completely. Once again, the car becomes eerily silent (unless you are cranking the tunes).
Computer control:
For your entire ride, the computer will be calculating when to let the gasoline engine do all the work and how much of a boost it needs from the electric motor. Because of the intermittent assist from the electric motor, the gasoline engine can achieve basically the same performance as a conventional car despite its smaller, more efficient size. Why put a monster gas-guzzling engine into a car, when most drivers never drag race?
Meanwhile, back in the Prius, you have zoomed over 15 mph. In fact, when you step on the gas pedal, you are really controlling a pedal positioning device which is telling the computer how fast you want to go, and the computer is once again making a lot of decisions about when to use the gas engine, when to go electric, or when to use a combination. The Prius computer is, in fact, sending its signals to a gearbox, known as the power split device, which connects the gas engine and electric motors through a series of gears.
Battery charge and discharge: You probably understand the basics of how the gasoline engine is working, but where is the electric motor getting its juice? It’s actually getting and giving power back and forth from a set of nickel metal hydride batteries. Once again, the computer is performing a lot of magic, by knowing when to reclaim excess energy when braking the wheels with the electric motor (which is now working like a generator). It also knows when to return the favor by passing power from the battery to the electric motor for acceleration. The computer is monitoring the amount of charge in the batteries, making sure that they never charge over 80% and never under 30% of their capacity. In this way, the batteries will last a couple of hundred thousand miles.
Wrap it all up:
Cover this technology with a frame that is built for maximum aerodynamics, and you’ve got yourself a major boost in fuel efficiency, and a big-time reduction in poisonous, global-warming-causing tailpipe emissions. It’s not rocket science off in the future. It’s better technology available today.
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