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How do Hybrids work? Newbie questions encouraged!

SylviaSylvia Member Posts: 1,636
Have you ever wondered how hybrids work? What is the technology behind them? What is the difference between Toyota's Prius and Honda's Insight? Here is the place to ask your questions.
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Comments

  • rfruthrfruth Member Posts: 630
    Whats the deal with iPod and BMW ? Are they (Apple) getting into the car business http://www.apple.com/ipod/bmw/ or am I reading too much into this ?
  • SylviaSylvia Member Posts: 1,636
    Hi Rob - probably a question better suited to the News & Views board. This discussion is geared towards how hybrids work. Thanks!
  • SylviaSylvia Member Posts: 1,636
    How a Hybrid Works (rewrite of an existing article)
    http://www.edmunds.com/ownership/techcenter/articles/45188/articl- e.html
  • SylviaSylvia Member Posts: 1,636
    What are the different types of hybrid cars and who is using what technology? Short list would do fine.
  • rfruthrfruth Member Posts: 630
    Prius & Escape = full hybrid = parallel hybrid


    Insight Civic and Accord = IMA = serial hybrid

    Silverado/Sierra = ? = starter/generator control module

  • stevedebistevedebi Member Posts: 4,098
    Insight Civic and Accord = IMA = serial hybrid

    A serial hybrid uses the engine to run the batteries, and has only electric propulsion. At least that is my understanding.

    I think the Honda IMA is a parallel system, because both the ICE and electric motors are engaged at the same time.
  • rfruthrfruth Member Posts: 630
    I stand by my original statement that the Insight Civic and Accord = IMA = serial hybrid
    however howstuffworks.com and Insightcentral.net http://www.insightcentral.net/encyclopedia/enhybrid.html say what you are saying and that is IMA is a parallel system, if you ask me (and others) IMA is just that integrated motor assist, it (the IMA electric motor) is in series with the gas motor, the vehicle can't move without the gas motor thus its a serial hybrid. Prius / Escape can use either or both thus a parallel hybrid.
  • stevedebistevedebi Member Posts: 4,098
    I'm not asking anyone's opinion, I'm stating facts. The words parallel and series have special meanings when it comes to hybrids. Here is the link for those who haven't seen it:

    http://auto.howstuffworks.com/hybrid-car2.htm

    "You can combine the two power sources found in a hybrid car in different ways. One way, known as a parallel hybrid, has a fuel tank, which supplies gasoline to the engine. But it also has a set of batteries that supplies power to an electric motor. Both the engine and the electric motor can turn the transmission at the same time, and the transmission then turns the wheels."

    Note that both Honda and Toyota hybrids fit this definition, though many Prius enthusiasts insist that the planetary gearset does not meet the qualification of a transmission. But it powers the wheels, so cut some slack here... the two terms refer to how the electric motors are used.

    "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."

    Emphasis is mine...

    Many Prius enthusiasts make their own definitions, based on the difference in the HSD, but that doesn't change the scientific literature. In implementation, the HSD does have the electric and ICE operating at the same time (different parts of the planetary gearset), and in the IMA the electric is in line with the transmission. This causes some confusion. I suppose that is why we have this forum...
  • stevedebistevedebi Member Posts: 4,098
    "IMA is just that integrated motor assist, it (the IMA electric motor) is in series with the gas motor, the vehicle can't move without the gas motor thus its a serial hybrid. Prius / Escape can use either or both thus a parallel hybrid. "

    Just to claify for the newbies:

    The IMA (Honda Hybrid) can move with or without the electric motor, at any speed, since the ICE is used at all times. It won't perform so well or get very good MPG though.

    The HSD (Toyota Hybrid) cannot move without the electric motor - battery power is all it uses up to about 15 MPH. At least, I've never seen any Prius enthusiasts claim it will move from a standing start with ICE only.
  • rfruthrfruth Member Posts: 630
    FYI do you consider howstuffworks.com scientific literature ? It doesn't really matter but I do know know the difference between a parallel and series hybrid - do note that the Prius can move without its electric motors and to say thats all it uses up to 15 MPH is just plain wrong, I don't know where you heard that but ask that source if the ICE ever runs when they are in reverse or at slow speeds (yes it does thus the parallel label, it can ((and does)) use either or both motors as needed)))
  • stevedebistevedebi Member Posts: 4,098
    "FYI do you consider howstuffworks.com scientific literature ?"

    I figured you'd probably catch that. No, not really, though I haven't ever caught them in a factual mistake (I've only checked the automotive stuff). I suppose I should have said "reliable" or "known factual" source.

    "do note that the Prius can move without its electric motors and to say thats all it uses up to 15 MPH is just plain wrong, I don't know where you heard that but ask that source if the ICE ever runs when they are in reverse or at slow speeds (yes it does thus the parallel label, it can ((and does)) use either or both motors as needed)))"

    Can you please quote me a "reliable" and "factual" source that says the Prius can start up from a standstill on ICE only? The ICE engine will engage at low speeds - to charge the batteries and power the electric motors. At least that is my understanding of the system from the Toyota web sites, which include some very nice animated graphics of the HSD system.

    It's only a side note anyway, since both IMA and HSD are not designed to work ICE only.
  • rfruthrfruth Member Posts: 630
    Glad you've seen the toyota.com FAQs for the Prius cause the very last one (# 25) reads Does Toyota support the modification of my Prius to be a plug-in Hybrid and run on electric only mode and the answer is NO (the ICE is sometimes used at slow speeds) but hey I'm no expert (although everything I've said I believe to be true) but you hybrid owners need to jump in here and tell us your experianes.
  • robertsmxrobertsmx Member Posts: 5,525
    Honda recently showcased a hybrid scooter prototype. It utilizes dual mode hybrid system (Series and Parallel, depending on situation). Here is how Honda differentiates between the two…

    “The hybrid scooter's internal combustion engine and direct rear-wheel-drive electric motor function in two distinct modes. In series mode, when riding on flat ground and when high output is not required, the engine alone powers the electric motor. In parallel mode, used during acceleration and when high output is required, the electric motor assists the engine. ”

    Based on this description, Insight and Civic Hybrid would qualify as Parallel Hybrid since IMA is an assist system. HowStuffWorks seems to describe it in a similar way.

    BTW, Honda FCX utilizes Fuel Cell Stack to help keep the ultra capacitor pack charged (no batteries in this case). This charge in the ultra capacitors is used by the electric motor to drive the vehicle.

    Technically…
    Series: One source transforms energy into a form that is utilized by another source to drive the vehicle (a “series flow”).
    Parallel: Multiple sources are used to drive the vehicle at the same time (in parallel). IMA or any assist mode hybrid would be a parallel hybrid.

    IMA also operates in series mode when necessary. Rolling down a hill, or when batteries need to be recharged, the electric motor doesn’t assist the ICE, but sends energy to recharge the battery pack.
  • john1701ajohn1701a Member Posts: 1,897
    > The HSD (Toyota Hybrid) cannot move without the electric motor - battery power is all it uses up to about 15 MPH.

    No offense, but that is totally incorrect.

    The limit for electric drive is 10kW.

    If you exceed 10kW, which usually happens when accelerating, the engine starts up.

    Cruising doesn't require that much electricity. So you actually can sustain speeds up to 42 MPH. And there is typically enough battery power available to do that for a mile or 2. Under ideal conditions, you can drive up to 3 miles using the battery.

    Then, it only takes about 10 minutes of driving at speeds above 42 MPH to replenish the charge-level to cruise on electricity for awhile again.

    > At least, I've never seen any Prius enthusiasts claim it will move from a standing start with ICE only.

    That's true... since HSD wasn't designed to do that. 100 percent of the time thrust is being sent to the wheels by the engine, electricity is also being generated. Remember, the A/C, steering, 2 small heaters, and many of the accessories (like the lights) require that electricity to run anyway.

    JOHN
  • stevedebistevedebi Member Posts: 4,098
    John, the quiestion was would the Prius work without a battery pack (pack totally depeleted, or whatever). That was what I was speaking of. Do you know if it will work, i.e., if the pack is totally depeleted, will the car drive without it?

    I realize, as I said before, that it is a moot point for the HSD, since it wasn't designed for that mode.
  • john1701ajohn1701a Member Posts: 1,897
    How exactly would you completely drain the battery-pack?

    The system has quite a few protective mechanisms preventing that from ever happening.

    JOHN
  • robertsmxrobertsmx Member Posts: 5,525
    Let us say a malfunction.
  • john1701ajohn1701a Member Posts: 1,897
    Any component in a vehicle can malfunction.

    Unless there is more than just a remote possibility of it actually ever happening, discussing it doesn't have a point.

    In other words, there is a higher statistical chance of being in an accident. So why focus on someless even less probable?

    JOHN
  • robertsmxrobertsmx Member Posts: 5,525
    Most people are wary of electrical systems in a hybrid, and how it interfaces with the rest of the drive train, than they are of any other system. So, it is logical to bring up that probability.

    But, my point was to bring out a scenario where electric supply fails for a moment. Would the gasoline engine be able to move Prius by itself?
  • tennisbird86tennisbird86 Member Posts: 5
    Toyota's Hybrid Synergy Drive is the most advanced automobile technology ever created. If I recall, the Prius (and all HSD vehicles) are equipped with at least five computers on-board to make constant calculations and adjustments. For all practical purposes, Toyota's hybrids (and now Ford's, as they're using the 1st generation Toyota technology), are supercomputers on wheels.

    Now, should the "electrical system" fail, what can you expect? Your car is broken. I speculate (though certainly can't confirm) that you can't drive because the car has an eCTV (electronically-controlled continually variable transmission). This isn't something to worry about, though. We're not talking artificial intelligence here, capable of destructing the world if it gets out of control... it's still a car. You should be more worried about a flat tire.
  • robertsmxrobertsmx Member Posts: 5,525
    I speculate (though certainly can't confirm) that you can't drive because the car has an eCTV (electronically-controlled continually variable transmission).

    If valid, this would answer stevedebi’s question.
  • tennisbird86tennisbird86 Member Posts: 5
    Ah, almost forgot.

    Should you decide you're not giving Shell one more cent of your money and run out of gas, the batter and motor are capable of propelling you for a short distance. Of course, this isn't good for the car but I have heard stories of Prius owners gliding into the gas station in purely electric mode.
  • tennisbird86tennisbird86 Member Posts: 5
    >If valid, this would answer stevedebi’s question.

    No, it doesn't really. I still think his question is about the equivalent to "If the gas all of a sudden magically disappears from the tank of my F-150..."
  • stevedebistevedebi Member Posts: 4,098
    "No, it doesn't really. I still think his question is about the equivalent to "If the gas all of a sudden magically disappears from the tank of my F-150...""

    Hmmm, considering the MPG of the F150, doesn't gas always magically disappear from the tank. You look down at the dash and - WHAM - there is the low fuel light...
  • rfruthrfruth Member Posts: 630
    We are making this hybrid 'thing' way more complacated than it needs to be ...

    How a Honda employee bakes a potato:
    Preheat new, high-quality oven to 350 F. Insert Idaho potato. Go do
    something productive for 45 minutes. Check for doneness, and then remove
    perfectly baked potato from oven and serve.

    How a GM employee bakes a potato:
    Instruct an Idaho potato supplier to preheat the oven to 350 F. Demand that
    the supplier show you how he turned the dial to reach 350F, and have him
    come up with documentation from the oven manufacturer proving that it was
    calibrated properly. Review documentation, then have supplier check the
    temperature using sophisticated temperature probe. Direct supplier to
    insert potato and set timer for 45 minutes. Have supplier open oven to prove
    potato has been installed correctly, and request a study proving that
    45 minutes is the ideal time to bake a potato of this size.

    Check potato for doneness after 10 minutes.

    Check potato for doneness after 11 minutes.

    Check potato for doneness after 12 minutes.

    Become impatient with supplier (why is this simple potato taking so long to
    bake?). Demand status reports every five minutes. Check potato for doneness
    after 15 minutes... After 35 minutes, conclude that potato is nearing
    completion. Congratulate supplier, and then update your boss on all the
    great work you've done, despite having to work with such an uncooperative
    supplier. Remove potato from oven after 40 minutes of baking, as a cost
    savings; without loss of function or quality versus the original 45 minute
    baking time. Serve potato.

    Wonder aloud what on earth those Japanese folks are doing over there to make
    such good low-cost baked potatoes that people seem to like better than GM
    potatoes.

    Daimler Chrysler's Baked Potatoes:
    Design great looking potato. Include sour cream, bacon bits, chives, and
    cheese. Bean counters then create MCM system. Engineers spend 2 years
    looking for ways to take out sour cream, bacon bits, chives, and cheese.
    Engineers find cheap imitation chives from Japanese supplier. Management
    commands engineers to use expensive, over-engineered German bacon bits to
    help prop up weak German suppliers. Sell potato with cheap imitation chives,
    no sour cream, cheese or expensive German bacon bits. Potato rots so fast
    customer swears never to buy another DCX potato.

    Ford's Baked Potatoes:
    Engineers create plain looking, "everyman" potato. Sold as "green"
    alternative to French Fries. When micro waved, potato explodes, causing
    death and injury to customers and bringing end to 100-year potato and
    butter-supplier relationship, lawyers flourish.
  • SylviaSylvia Member Posts: 1,636
    that was a humorous interlude...and now back to questions on how hybrids work.
  • xcelxcel Member Posts: 1,025
    Hi Sylvia:

    ___You mean mine doesn’t have a cute little squirrel in one of those round cages chasing its tail going roundy roundy? I guess I had better open the hood and see what is actually underneath it :D

    ___Good Luck

    ___Wayne R. Gerdes
  • robertsmxrobertsmx Member Posts: 5,525
    Your response did not relate to mine. The original point surrounded failure of electric assist in Prius, not running out of gas.
  • stevedebistevedebi Member Posts: 4,098
    "that was a humorous interlude...and now back to questions on how hybrids work. "

    Well, I was assuming it was a gas + electric stove being used to bake the potato...
  • ryantryant Member Posts: 3
    I am looking into buying a hybrid. I would like to use my garage. Is that okay? Thanks in advance!

     

    RyanT
  • Kirstie_HKirstie_H Administrator Posts: 11,145
    Your question isn't clear. You would like to store your hybrid in your garage? Or are you asking about maintenance & repair?

     

    kirstie_h

    Roving Host & Future Vehicles Host

    MODERATOR /ADMINISTRATOR
    Need help navigating? kirstie_h@edmunds.com - or send a private message by clicking on my name.
    Share your vehicle reviews

  • ryantryant Member Posts: 3
    I would like to park it in my garage. Is that safe?
  • SylviaSylvia Member Posts: 1,636
    Yes. Why would you think it would not be safe?
  • electrictroyelectrictroy Member Posts: 564
    He thinks the ~200 volt hybrid car will somehow catch the house on fire...

     

    ...never mind that the house has LIVE 220 VOLT WIRES running through the walls! (shaking head) People are strange.
  • ryantryant Member Posts: 3
  • jpricejprice Member Posts: 58
    I am unclear as to the exact behavior of the regeneration function.

     

    Are there quantitative differences in regeneration between a) coasting; b) braking, and c) coasting in "B"? Also, when the display indicates that the ICE is supplying power to the wheels and also recharging the battery, is this a different level than the three modes mentioned above?

     

    Thanks for any clarification.

     

    jprice
  • stevewastevewa Member Posts: 203
    My $.02...

     

    Since the "electric assist" of the Prius drive system is in fact an integral part of the drivetrain (unlike Honda IMA which is only supplemental) were the electric drive to fail, the car is basically out of operation. However, because the designers realized the critical nature of the electronic componentry of the THS/HSD system they took a lot of pains to make it as robust as possible.

     

    With the power split device, if you don't have control over the rotation of the motor/generators you don't have the ability to modulate the effective gear ratio of the drivetrain. So a better comparative question to ask is would your F-150 run if the transmission were to suddenly seize up or lose its fluid?
  • typesixtypesix Member Posts: 321
    Do the friction brakes on the axle supplying regenerative braking stay off till regenerative braking fades or is it a blended system where both are active?
  • robertsmxrobertsmx Member Posts: 5,525
    No, they are still on but to a lesser extent than they would be without regenerative braking.

     

    In "motor" mode, the electric motor is providing torque to the wheels to turn. Now when you have to stop in a vehicle without regenerative braking, you must apply brakes sufficient to counter the torque (and energy is lost in the form of heat).

     

    With regenerative braking, the electric motor now becomes a generator (role reversal), converting mechanical energy to electrical energy. Some of the torque from the turning wheels now drives the generator which manages to capture some of the overall energy into useful form (electric charge). For the rest, you would still need to use conventional brakes.

     

    Regenerative braking simply reduces energy lost by minimizing the need for conventional braking (as much as possible).
  • typesixtypesix Member Posts: 321
    Thanks for the answer. I was curious as to how the braking was setup, as many mass transit vehicles such as subways/streetcars are set up to hold off the friction brake till the dynamic/regenerative braking fades, usually 15 mph or down to 1 mph with electronic controls.
  • xcelxcel Member Posts: 1,025
    Hi Typesix:

     

    ___Except under a given higher then normal brake pedal pressure in which all Regenerative braking is overridden to allow ABS (Anti-lock Brakes) in the case of the HCH (Honda Civic Hybrid) and Insight, ABS, EBD (Electronic Brake Force Distribution), and TC (Traction Control) in the case of the AH (Accord Hybrid), and ABS, EBD, TC, VSC (Vehicle Stability Control), and BA (Brake Assist) in the case of the Prius II if so equipped.

     

    ___Good Luck

     

    ___Wayne R. Gerdes
  • robertsmxrobertsmx Member Posts: 5,525
    Except under a given higher then normal brake pedal pressure in which all Regenerative braking is overridden to allow ABS

     

    This brings up an interesting perspective. Why would regenerative braking be overridden for ABS? ABS should be independent of the transformation of electric motor into an electric generator and monitor/impact wheel lockup during braking.
  • xcelxcel Member Posts: 1,025
    Hi Robertsmx:

     

    Why would regenerative braking be overridden for ABS? ABS should be independent of the transformation of electric motor into an electric generator and monitor/impact wheel lockup during braking.

     

    ___The lowest rotational speed of any/all wheels during an impending ABS or other safety function is probably to slow or switching so fast from impending lockup to release and back again for regen to recover anything anyways so it’s best to remove the Regenerative braking functions for safety purposes. I am sure the engineers that designed the various regen and assist systems were given a design basis that under any emergency, all regen and assist functions are not to interfere with the safety engineered functions in any way shape or form. This is the case with the Insight and I have not read of anything different with the HCH, AH, or Prius II yet.

     

    ___I have read of future hybrid electric drives that will control all safety functions vs. locked out as is the case today. If the electric drives were designed to switch this fast, they probably could but I don’t think we are ready for brake by wire and electrics just yet ;-) In the case of the Insight, the transition from regen to release or assist or assist to regen isn’t nearly fast enough for any emergency braking condition in my experience. The HCH, AH, and Prius should have improved upon this but the electrics are asked to perform a huge task to switch from regen to release and back so many times a second for such little M/G sets that it makes sense to me to leave them out of the equation.

     

    ___Good Luck

     

    ___Wayne R. Gerdes
  • robertsmxrobertsmx Member Posts: 5,525
    As I understand, the forward momentum of the vehicle forms the premise for regenerative braking. The vehicle does not stop rolling when ABS engages. And that kinetic energy (moving vehicle) is transformed into potential energy (electric charge) via regenerative braking. ABS is supposed to provide for a non-slip braking at the rubber, which under ideal conditions would be accomplished without.

     

    Unless this has anything to do with reliability issues of the overall system (not so smooth deceleration), I don't see a point in ABS overriding regenerative braking.
  • xcelxcel Member Posts: 1,025
    Hi Robertsmx:

     

    Unless this has anything to do with reliability issues of the overall system (not so smooth deceleration), I don't see a point in ABS overriding regenerative braking.

     

    ___I guess you had better take that up w/ the 1000’s of engineers that work on the hybrid programs at Ford, Honda, and Toyota then.

     

    ___Good Luck

     

    ___Wayne R. Gerdes
  • robertsmxrobertsmx Member Posts: 5,525
    Well, mine is a valid question, too bad we don’t have those engineers work on this thread. So, the answer remains to be seen.

     

    In fact, I firmly believe that it would be possible to integrate ABS and regenerative braking by completely eliminating the involved hydraulics. It is not the electrical systems that are slow, quite the opposite from what you suggested earlier. “Speed”, which should translate to smoothness and effectiveness, would be an advantage with electrical/integrated system.

     

    The way I see it, potential of slow reaction/action time from hydraulics may be to blame if there is an exclusion involved in all regenerative systems from ABS. If true at the moment, this may be a non-issue in the future where electric motors may control ABS. And not just ABS, but AWD system itself could see mechanical systems giving way to electro-mechanical systems (for the very same reasons). In case of AWD, we already see a few systems around.
  • xcelxcel Member Posts: 1,025
    Hi Robertsmx:

     

    ___It is possible and I have already stated that many of today’s safety functions will be integrated into the Hybrid drivetrain but they are not today in the case of the Honda’s and probably not the Toyota.

     

    ___Good Luck

     

    ___Wayne R. Gerdes
  • robertsmxrobertsmx Member Posts: 5,525
    And likely because of poorer performance of hydraulic systems (current ABS designs). Thats where evolution of hybrid systems come into play. Too early to have everything in place. It will happen eventually. Something I say frequently... one step at a time.

     

    The question however is, besides (relatively) slow response of hydraulic systems (which translates to non-linear deceleration), I don't see a reason why ABS/regenerative systems couldn't exist. But then, I don't know everything. Perhaps someone here does.
  • xcelxcel Member Posts: 1,025
    Hi Robertsmx:

     

    The question however is, besides (relatively) slow response of hydraulic systems (which translates to non-linear deceleration), I don't see a reason why ABS/regenerative systems couldn't exist.

     

    ___Have you ever driven a hybrid? If you have, you must have missed the non-linearity of regen braking. If you haven’t, they why bother making suppositions?

     

    ___Good Luck

     

    ___Wayne R. Gerdes
  • robertsmxrobertsmx Member Posts: 5,525
    We couldn’t take this any further if you firmly believe electrical systems are slower than hydraulic based systems.

     

    We're talking about tiny fractions of a second. You're not going "to feel it" simply by driving a vehicle. System is much faster than we humans can perceive/experience things.
This discussion has been closed.