Environment & Energy

(and the last paragraph is about plug in ones)

What Is a Hybrid Car and How Do They Work?
https://www.caranddriver.com/features/a26390899/what-is-hybrid-car/
What Is a Hybrid?
How Does Regenerative Braking Work?
Parallel Hybrids
Series Hybrids
Blurred Lines
How Hybrids Benefit You
Other Types of Hybrid

Everything in the below is my own words, unless its shown in quotes or by a gray excerpt box.

It's important to understand regenerative braking, since that's the main way a hybrid is fuel-efficient. When you press the brake pedal (not real hard, rather, like one normally does to slow down or slow to a stop), the cars wheels becomes attached to an electrical generator and start turning that generator. Turning that generator is hard as heck to turn because, well generating electricity is hard work (think of an ordinary bicycle's electric generator that you engage to connect to the bike's wheel that feed's the bike's light -- its a lot of work to light that light! (I suppose most bikes these days, as in the past, use a couple of D battery cells instead to power the lights).

Or in the mini-museum that was in the Mpls Central Library years ago, there was something like an exercise bike that one pedalled to light an ordinary 60 watt bulb, and it really took a lot of pedalling effort to make that light glow strongly and stay lit.

Well, back to our hybrid, that effort coming from the car's wheels that is generating the electricity to feed the battery is a lot of effort and that slows the cars' wheels down (and the car slows down of course). And the battery is charged some. Its a small battery in a hybrid (the article says about 1 kwh), but nevertheless its a useful amount of energy that is being captured and stored by the battery. And that battery energy is then used to get the car going again.

And that gives the hybrid a big efficiency advantage over an ICE car (traditional Internal Combustion Engine car), where all braking is done by squeezing brakepads against the wheel's rotor and all that energy is lost by heating up the brake pads and the surrounding air. Whereas the hybrid utilizes that energy by charging up the little battery, rather than totally wasting it like an ICE car does.

Next, lets skip to the Series Hybrids topic which is conceptually the simplest. The generator and battery and electric motor move the wheels at all speeds. The internal combustion engine never engages directly with the cars wheels, rather, it always engages with the generator to turn it to generate electricity which in turn powers the electric motor to turn the wheels. IOW, all the force (torque) to turn the wheels comes from the electric motor supplied by the electric generator and battery.

the article says, "Series Hybrids - This type is less common, but popularity is increasing."

Now scrolling up to "Parallel Hybrids" which is the most common but is more complicated. When the car starts moving, the battery-generator powers the electric motor to turn the wheels, just like described above. As it speeds up, or the little battery becomes exhausted, the internal combustion engine engages directly with the wheels (well to the transmission system that then turns the axle really, but I'll just shorthand it to say the engine is turning the wheels) to turn them. So now we're in plain ordinary ICE car mode - a gasoline engine turning the wheels.

Now excerpting from the first topic, "What is a hybrid?"



So the interesting part is that the regular internal combustion engine is frequently starting and stopping and starting and stopping again and again during city driving.

I don't understand the very last part of the excerpt where it says "This makes a hybrid's city fuel economy much higher than a nonhybrid's, not to mention its own highway economy.

The bold part (I did the bolding), befuddles me. As I understand it, on the highway, one is almost always in internal combustion engine mode. In the parallel hybrid, the ICE engine is directly turning the wheels, just like in a conventional ICE car, so I don't know how it can be more efficient than a conventional ICE car (particularly with the added weight of a dual motor system plus the 1 Kwh battery in the hybrid's case).

Well, I suppose, in highway driving, we're often doing a little very gentle braking now and then to adjust our speed downward a bit at times, so the hybrid's regen system captures that and uses it (rather than wasting it like an ICE car).

In the series hybrid, in highway driving, the ICE engine is constantly turning the generator that feeds the battery and electric motor to turn the wheels. It would seem to me that this is not particularly efficient -- some of the energy from the ICE engine is lost in converting to electricity and then from electricity to the electric motor to the wheel -- whereas in an ICE car it's direct from the ICE engine to the wheel (by way of the transmission system etc. as always).

And, ta-dah, plug-in hybrids