Do Hybrids Really Make Sense?

[Xist]

Whatever I write about this on here, people argue with me, but you can have an ICE-only Gen1 Insight, still have "adequate" acceleration, and get better fuel economy than most cars. The Gen2 Prius traction battery weighs 117.5 pounds and the Gen1 Insight one weighs 65 pounds. If you disable or remove the battery, the electric motor and other components become useless. The Gen1 Insight weighs 1,847 pounds and the Gen2 Prius weighs 2,903; if ten percent of their weight was the hybrid part, it would only cost around five percent more fuel to move it.

The other point that people have not mentioned yet is battery replacement. According to Toyota Hybrid Battery Replacement Cost Guide, the average cost to replace a First- or Second-generation Prius battery is $2,299. You can get a Civic HX for that price and I have had 50-MPG tanks, but the traction battery would last a couple of times as long as my timing belt.

Wouldn't it, Old Mech?

That same page says that people almost never need to replace hybrid batteries, but I see Prii with worn-out batteries on Craigslist all of the time.

Then there is the "Out of my way! I am saving the world!" phenomenon.

[Baltothewolf]

Originally Posted by Xist

Whatever I write about this on here, people argue with me, but you can have an ICE-only Gen1 Insight, still have "adequate" acceleration, and get better fuel economy than most cars. The Gen2 Prius traction battery weighs 117.5 pounds and the Gen1 Insight one weighs 65 pounds. If you disable or remove the battery, the electric motor and other components become useless. The Gen1 Insight weighs 1,847 pounds and the Gen2 Prius weighs 2,903; if ten percent of their weight was the hybrid part, it would only cost around five percent more fuel to move it.

The other point that people have not mentioned yet is battery replacement. According to Toyota Hybrid Battery Replacement Cost Guide, the average cost to replace a First- or Second-generation Prius battery is $2,299. You can get a Civic HX for that price and I have had 50-MPG tanks, but the traction battery would last a couple of times as long as my timing belt.

Wouldn't it, Old Mech?

That same page says that people almost never need to replace hybrid batteries, but I see Prii with worn-out batteries on Craigslist all of the time.

Then there is the "Out of my way! I am saving the world!" phenomenon.

It's more of the age of the battery, if you grid charge and what temperature climate that you live in that determines the life. The insight doesn't require a timing belt, and still gets the same mileage as the HX without the IMA, and 10+ better with it. So idk, to me, hybrids make sense if you grid charge/garage your car to keep it out of the searing heat.

[redpoint5]

Originally Posted by EVmetro

...how many of them actually understand the principles of physics and thermal dynamics? Are hybrids really any more fuel efficient than a regular full time gasoline burning car?

1. Add me to the list of hybrid owners that understand the principles of thermal dynamics.

2. Yes, hybrids really are more fuel efficient than their ICE-only counterparts.

Originally Posted by EVmetro

I am very interested in finding out if there is some scientific explanation that shows how hybrids really do use less fuel than a comparable ICE. So far, all I can see that is unique about hybrids, is that they are able to harvest a portion of braking energy and distribute it at the appropriate time.

The scientific explanation is that an electric motor can allow the gas engine to be sized smaller and tuned less powerfully while maintaining the consumers expectation for acceleration. Comparing hybrids with their non-hybrid counterparts bears this out.

Regen is a small part of the efficiency equation. A smaller, more efficient engine is a larger factor.

My Prius is the plug-in version, so most of the trips it makes consumes zero gasoline. Coming back down from the mountain today, I regained about 5 EV miles due to extensive regen. I can run the ICE when there is a high demand for power, which is the most efficient use of the ICE, and run the electric motor when the demand for power is low. I'm probably averaging 75 MPG compared to my TSX, which with great effort, achieves 30 MPG. The 2 cars are comparable in weight and size, with the Prius having more utility.

[planetaire]

Originally Posted by EVmetro

...Sometimes I stew about the idea of getting my hands on a Prius and converting it to strictly ICE, with the intent of finding out the difference would be in fuel economy. This is not a very realistic thing to do since so much of it is integrated, but it is a neat thought. I would put my money on an all ICE Prius for driving a long distance on flat ground, but I don't know enough to predict an around town winner.

Hi, Evmetro

I have a gen2 prius (diy plug-in) and use it in 100% ev mode since more then 6 months. It is possible from 0 to 85 km/h with a factory prius with just more battery. No need to "convert" the car in this speed range.
If you compare the mecanical energy needed at the wheel level, with or without the engine, you will find the same value. Except that if you use the engine, you will lose thermal energy because this engine have to be used up to 90°C and this will be lost during parking after your trip.
If you want to reduce you "primary" energy consumption, use low rolling tires and aerodynamic improvements (wheel cover ...)

In this graph you have energy consumption (blue curb)

Higher each winter of course, but it have been decreased not since I add battery (First 4.5kWh, since 2012 9kWh and now 20kWh) but since improving tires and aero.
Before mecanical energy was between 100 and 120 Wh/km (160 to 190 Wh/mile) and can now goes under 90 Wh/km.

(Orange curb is gasoline consumption in Liter/100km)

[EVmetro]

Originally Posted by redpoint5

1. Add me to the list of hybrid owners that understand the principles of thermal dynamics.

2. Yes, hybrids really are more fuel efficient than their ICE-only counterparts.




The scientific explanation is that an electric motor can allow the gas engine to be sized smaller and tuned less powerfully while maintaining the consumers expectation for acceleration. Comparing hybrids with their non-hybrid counterparts bears this out.

Regen is a small part of the efficiency equation. A smaller, more efficient engine is a larger factor.

My Prius is the plug-in version, so most of the trips it makes consumes zero gasoline. Coming back down from the mountain today, I regained about 5 EV miles due to extensive regen. I can run the ICE when there is a high demand for power, which is the most efficient use of the ICE, and run the electric motor when the demand for power is low. I'm probably averaging 75 MPG compared to my TSX, which with great effort, achieves 30 MPG. The 2 cars are comparable in weight and size, with the Prius having more utility.

This is a good summary of this thread so far. When you introduce a plug in hybrid, all bets are off, since you are introducing energy from an outside source. At this point you are gaining many of the advantages of an EV, and are no longer relying only on what you pump into the gas tank.

The smaller ICE that works as a system with an electric motor is a concept that is a bit of a breakthrough for my understanding of hybrids, but I still have questions about this. It still takes a certain amount of energy to drive a car of a certain weight and cd, and I don't fully understand how the Atkinson engine coupled to an electric motor benefits this. The concept of the system makes sense, but it also sounds like the battery pack will need quite a bit more than just waste braking energy. This means that the ICE will need to produce energy to store in the batteries. An ICE powering a generator that charges batteries that run a motor adds up to a loss of energy. What I am unclear on is how much of this loss is offset by the advantage of the Atkinson drive system and the harvested braking energy.

[vibrating_cake]

I will have to butt in here.
No, the ICE in a Hybrid is no more or no less efficient than the ICE in a non-hybrid.
I have a honda CRZ (yes i am one of the few!) basically a manual transmission IMA system, that never runs on full electric.

Now, the hybrid system on this car is not a high percentage of the cars weight (5% from what i worked out when i first got it) so that in its-self is rather negligible to mpg over the lifetime of the vehicle.

Here is where i bite.
I can drive more efficiently in NORMAL mode rather than ECO mode.
ECO mode basically runs minimal ICE and a high percentage electric power (all of which is recovered from braking/during steady state driving at approx the 50mpg(uk) mark.
NORMAL mode runs the ICE on a "normal" ICE setting, i.e. normal pedal map, normal timing, normal usage. But when you use more than a certain percentage throttle input the electric (which has previousley been harvested from going down a hill) gives it a good shove, but it does it only on say 30% plus throttle input

This does not make the ICE more efficient in its self, but it allows the ice to say run 80% of the throttle seen for the same total output ICE+IMA
Same scenario without IMA you are running say 90% throttle application for the same output.

(guesstimating numbers)

so, we know under acceleration the IMA helps output per amount of fuel ratio.

Now steady state on the motorway (highway)
Same thing, steady state driving 30% throttle application @ 70mph
BOTH cars with and without IMA run exactly the same MPG, same throttle position etc.
but you loose nothing for your weight (if you are on level ground)

Steady state driving uphill motorway (highway)
you are now running 30% throttle with 10% IMA
40% throttle on the non IMA equipped car, therefore, the engine is no more efficient, but your mpg doesn't drop as low as it would without the help of the few bhp output from the electric motor.

and again, downhill motorway (highway)
DFCO + REGEN IMA (harvesting)
DFCO + no IMA regen (rolling)

equal mpg for the both.
BUT you can DFCO longer with no IMA REGEN, (rolling/coasting) so you get a +1 on the non hybrid.

At lights, lets say we have auto stop on both cars, equal

so...
hybrid vs non hybrid

acceleration advantage hybrid (say 5%)

steady state advantage non hybrid (weight, say 2.5%)

Uphill steady state adv hybrid (say 5% again)

Downhill steady state, tricky one, i'd say equal advantages between the two.

Now, stopped, IMA equipped cars have a larger capacity battery, so it can be stopped without the engine on (with ancillaries on) for longer, so +1 for the hybrid, but no percentage gain unless you are really stopped for long periods.

If you end up adding all of these up, for a specific number input (petrol/gas in litres/gallons) Hybrid has the advantage, but it's pretty marginal depending on the situation.
Say high use of motorway/highway, i see them being equal.
High use in a city, stop start, i see hybrid on top, nearly every time!
High use mixed... hybrid probably takes the biscuit, but not by much.
High use in a mountainous area (where you fully deplete the battery on the hybrid) the non hybrid has the advantage.

We can see this in the estimated MPG numbers, highway are pretty much even the hybrid eeks it out on the mixed and city cycle.

So in real terms, they are marginally more efficient, all things being equal, as long as you don't live in the mountainous parts of the world or do mega highway miles.

It all depends, can you regenerate the percentage of ENERGY lost for the weight of the hybrid system in your situation. Most of the time yes, a few situations, no.
But the few situations equal a small percentage of the total hybrid use, so yes they make sense.
unless you are commuting over the alps, or you do a majority of motorway(highway) miles, then a diesel is your best bet.

A couple of numbers,
43mpg UK 1.5 petrol IMA Honda crz. Petrol is £1.06 average
43mpg UK 2.2 diesel Honda civic. Diesel is £1.13 average

My last commuter (12.5miles motorway/highway)
50mpg UK 1.5 petrol IMA Honda crz
63mpg UK 2.2 diesel honda civic....

Thats my two cars, on exactly the same commute, averaged over 6 months of summer-winter driving, 18miles each way.
I had to eek everything out of the diesel to get that MPG, the CRZ does that even if i do drive like i just passed my test on a country road!

Go figure!

[MetroMPG]

Originally Posted by vibrating_cake

No, the ICE in a Hybrid is no more or no less efficient than the ICE in a non-hybrid.

Research Atkinson Cycle vs. Otto Cycle and get back to us on that.

Welcome to the forum!

[vibrating_cake]

is this thread not about hybrids making sense, and actually making a difference via their identicle other? i.e. the earlier Jazz/Fit comment, all being equal, would the hybrid be better/make sense?

[pgfpro]

Oh boy, oh boy this thread is about to get interesting?

[Fat Charlie]

And that's all I have to say about that.