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Honda Insight MPG-Real World Numbers

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Comments

  • albalmaalbalma Posts: 10
    jburnelle, how about the Volt? It is expensive, but if you can afford it, it has great range and is mostly an EV with a fuel recharger.
  • I have a 60 mile commute one way. I live in the Catskill Mountains. I go down the moutain for about 10 miles, then it flattens out for 20 miles and I go 64 MPH on cruise control. Then I get on the Thruway for another 30 miles. Flat and I go 73 MPH, on cruise control. The winter's are long here. And then I have to go up the 10 miles on the way home. Parts of the climb are fairly steep. In my Camry, it jumps to 2200 at about 45 - 50 MPH (it's an older car). I've been reading this terrific forum because I really want an Insight...I like the looks and it's a Honda...but I'm wondering if my commute is wrong for this car? If I go any slower, I would never get to work. I will say, in the winter I go slower because it's dark and I don't want to hit a deer. Any insights (pun intended) would be very helpful. Thanks.
  • albalmaalbalma Posts: 10
    You will get anywhere from 46 to 50 mpg, even running the air conditioning at that speed, that is supposing that you get a lot of efficiency on the way down and then it goes down on the way back, when you are climbing. You should get 100+mpg on the way down, even at 70, when flat you will get anywhere from 45-50 at that speed and then on the way up it can go anywhere between 30 and 45, depending on how steep the climb is. I have even done 80 (on a 70 road, somewhat flat), with no less than 40-45 mpg. Road conditions are important, but how many mpg's do you get in your Camry?
  • stevedebistevedebi LAPosts: 3,786
    'A while back you suggested that to optimize mileage, you should try to drive on the electric motor only for a long as possible. You described this as "free mileage". I would have to disagree with that recommendation and here's why... "

    The Honda hybrid system does not have a pure electric mode. When it is moving, the engine is running.
  • kidsidkidsid Posts: 10
    Not true. I'm an electrical engineer who put himself thru college as an automechanic. 20+ years of working on cars and designing computer chips. I also own the vehicle,... 2010 Insight EX with Nav, Atomic Blue. I assure you it does.
    You can get the electric motor to power the car by itself. If you own one, toggle over to the information display page that shows the battery level. As you are driving you can see how the energy flows to and from the car, battery and gas tank. When you see an arrow pointing from the battery to the car by itself, that means that the electric motor is keeping the car moving. See this youtube link of someone doing it:

    http://www.youtube.com/watch?v=1vMAb5DOl5Q

    When this happens, the gas engine is still turning but it is not running because the hybrid control computer has shutoff the fuel to the fuel injectors.
  • kidsidkidsid Posts: 10
    Here is a graphical depiction of the various modes of operation on the Insight powertrain:

    http://www.youtube.com/watch?v=xmDkc8SEvwc&feature=related
  • stevedebistevedebi LAPosts: 3,786
    edited August 2011
    "If you own one, toggle over to the information display page that shows the battery level. As you are driving you can see how the energy flows to and from the car, battery and gas tank. When you see an arrow pointing from the battery to the car by itself, that means that the electric motor is keeping the car moving. See this youtube link of someone doing it: "

    Possibly I should have said that the engine is turning over whenever the car is moving. Strange in a way, because that means the electric motor is having to push the cylinders, which takes more energy. But I suppose that is because the IMA has the electric motors around the driveshaft, making it impossible to completely disconnect the electric from the mechanical (unlike the Toyota and Ford hybrid systems).
  • albalmaalbalma Posts: 10
    The electrical motor is not having to push the cylinders because the valves are closed, which makes it a push-compress cycle, which does not add to the energy spending. You do have the friction of the cylinders moving though, so it probably is a less efficient system, however, the lower weight should make up for it, at least some.
  • kidsidkidsid Posts: 10
    Not quite. As you mentioned, there are energy losses do to friction. However, the push-compress cycle you mention is not an adiabatic process. When air is compressed, it heats up. Some of this heat is loss thru the cylinder walls via the cooling system. This heat loss is energy loss that adds to energy spending. Obviously not an ideal situation. A lower cost solution compared to Prius, but still quite effective.
  • spunjornospunjorno Posts: 45
    edited August 2011
    Sorry, I didn't mean to be misleading with the phrase "free mileage". Of course it's energy that you've already paid for - you burned gas to get that energy stored in the battery. But using it in the way I've mentioned is a little like finding a five dollar bill in the pocket of pants you haven't worn in a while. It FEELS like free money even though it was yours to begin with. You see, also being an electrical engineer like yourself, I find when writing on these boards if I write like an engineer then no one but engineers will understand me. I'm guessing the audience here has wide varying levels of technical understanding and I'd like everyone to be able to follow the discussion regardless of background. So at the risk of occasionally being slightly technically imprecise, I will sometimes bend science to a small degree to try to better get the point across. Which leads to phrases like "free mileage".

    I read your post and agree technically with everything you said. Although, I'd still like to defend my previous recommendation. But first, it was correct of you to point out that when using the energy stored in the battery, some energy is lost in the conversion process. I call this "The Conversion Tax" and had planned to do a couple of posts on this subject with some specific recommendations at a later date. And of course, the conversion tax must be paid when storing the energy in the battery too - so you have to pay the tax BOTH ways. So you are correct that if you use the battery power to maintain speed you are going to pay the tax twice, as opposed to maintaining speed using gas only.

    You also pointed out that the battery energy is supposed to be used for acceleration. But remember, some of my other posts were geared towards reducing the amount of overall energy used during acceleration. That will also use less stored battery energy. The end result is that more energy is left in the battery. And since normal driving with the Insight also further charges the battery, you often can reach a point where the battery is almost at full charge. And now it is time to brake. PROBLEM... If your battery is full before you start to brake, you won't have any battery capacity left to store the energy of braking. An now your hybrid momentarily becomes a normal car and uses only the wasteful friction brakes to stop the car. That wastes a LOT of energy. Way more than paying the conversion tax. This wouldn't happen if you tried to use up some of the battery energy while driving. So it's a matter of sacrificing a little efficiency in order to not waste a big gulp of energy. Besides, remember that the amount of conversion tax you pay increases with the amount of current in/out of the IMA. Well when using battery to maintain speed the current remains very low. And battery charging during driving is similar. So the "tax" (loses) are low too.

    One more supporting point. When driving on battery only, you sometimes don't have to try and make it happen. The car will do it on its own. Honda seemingly has provided this as a benefit. The same can be said for the Prius. If it was a wasteful thing to do, Honda and Toyota probably would have not included it in the software algorithm. ...And I seem to notice better mileage when I've been able to do it more.

    New topic: The time my headlights ran down the hybrid battery...
    What you say sounds correct. What puzzles me is that while stopped in traffic in AUTOSTOP (engine not running) and no other accessories on except headlights, I watched my IMA battery display slowly deplete down to zero over the course of about an hour. At that point the car came out of AUTOSTOP and stayed that way until I was able to drive and charge up the battery again. So now I'm confused as to what discharged my 100V battery down to zero. Is there a converter to charge the 12V battery from the 100V battery? What else would stop the 12V battery from running down during AUTOSTOP?
  • spunjornospunjorno Posts: 45
    edited August 2011
    "When this happens [running on battery only], the gas engine is still turning but it is not running because the hybrid control computer has shutoff the fuel to the fuel injectors."

    Listening to the engine when driving on battery only would suggest that the fuel injectors are not entirely shutoff. You can still hear combustion. The car sounds the same as when idling. Compare the sound when driving on battery to the sound when the car is in AUTOSTOP but still moving - it's very different. In AUTOSTOP you can hear the gas engine has turned off.

    Another experiment: While driving down a long hill in battery mode only, I listened to the engine (and still heard and felt it idling). I was going about 40MPH. And then I turned off the ignition with the key while still movng and with the car still in the drive gear. Then the sound was VERY different. You could no longer hear and feel the gas engine idling and could tell it was really off.
  • stevedebistevedebi LAPosts: 3,786
    "Listening to the engine when driving on battery only would suggest that the fuel injectors are not entirely shutoff. You can still hear combustion. The car sounds the same as when idling. Compare the sound when driving on battery to the sound when the car is in AUTOSTOP but still moving - it's very different. In AUTOSTOP you can hear the gas engine has turned off.

    Another experiment: While driving down a long hill in battery mode only, I listened to the engine (and still heard and felt it idling). I was going about 40MPH. And then I turned off the ignition with the key while still movng and with the car still in the drive gear. Then the sound was VERY different. You could no longer hear and feel the gas engine idling and could tell it was really off. "

    I suspect that if someone hooked up a scanguage II and programmed it correctly, the fuel cut-off (or lack thereof) would be obvious. I know that my FEH cuts off fuel when above a certain state of charge and going downhill, for example.
  • kidsidkidsid Posts: 10
    I see your point.
    However, I think that at some point, you just have to let the car's electronics manage things. Trying to make sure that when you brake, you always have someplace for the energy to go? Wow! Good point but that's further than even I want to take things! Good catch though.

    Running on the battery alone is not a "feature" I would think Honda provided as a benefit. I think it is more likely a loophole in their hybrid control algorithm. If it were a "feature" I think they would advertise it as such.

    Ideally, you want the electric motor to run where it adds the most value, and that is when there is a need for high torque, i.e. acceleration. Any other use is less efficient, except for maybe the case that you pointed out. I would love to see some equations to prove that but agree, you might be right. The most efficient condition would be when the car is traveling at a constant velocity, and the battery is fully charged.

    I think I'll try something. Find a nice flat stretch of highway. When I start, the electric motor is used to aid acceleration. Once I reach cruise velocity, the battery starts to recharge. Now, based on your theory, the battery will charge fully, leaving no place to put the energy gathered by regenerative braking when I stop. If the algorithm is smart, it would always leave a some battery capacity for this energy recovery. Or would that be the smartest thing to do?

    I wouldn't be suprised either way because, it seems to me that it depends on how you want to hedge you bet. If the car's computer knew that you where approaching a long downhill run, it would not bother recharging the battery with the ICE at all but simply wait until you start to go downhill. Now if the car's computer knew that you where approaching a long climb through the mountains, it would go ahead and charge the battery to peak capacity while it could. Since the car cannot possibly know what's ahead, I think the safest thing to do is to top off the battery. So I think you are right.

    "New topic: The time my headlights ran down the hybrid battery..."

    I know that the traction motor is used to charge both batteries. There is no seperate alternator on this car. Now with your headlights on, you would be depleting the 12V accessory battery under the hood. Perphaps the computer sensed this drain, and directed the ICE to start, charging the 12V battery. But that doesn't explain the graphics showing you a depleting traction battery. Hmm... I'll have to look into this question a bit more throughly and get back to you...
  • kidsidkidsid Posts: 10
    Hmm,... Well, It seems I have two choices here.
    I can agree with you based on what your senses tell you is going on under the hood, or I can agree with the manufacturer.

    I think I'll go with the manufacturer on this one spunjurno! With all due respect, I think the engineers who built the thing can give us a more accurate description of what is going on.

    If you are correct, that would mean that Honda is, well, just plain lying about the product. What would be the point of that?

    Fact is, when you turn the key to the OFF position, you are doing alot. You are shutting off power to the electrical motor used for steering assist, you are shutting down the electric fuel pump, inverters, panel electronics, etc., all of which contribute to the sound you hear in the car. The difference is more than you think.

    If you want to prove your theory, come up with some way to measure the pressure of the exhaust at the tailpipe. Maybe a small trapped door that will open with the pressure of combustion while the engine is running, and stay closed when it is not. Perhaps a small remote camera strategically located can record the events. The valves stay closed when the engine is shutoff so there should be no exhaust pressure,... well..., according to the manufacturer! :-)
  • "...I think that at some point, you just have to let the car's electronics manage things..."

    Well certainly you can't go too horribly wrong with that strategy since the engineers did a pretty good job designing this car. But until engineers are able to come up with an electronic clairvoyance feature, then there will always be room for the driver to improve performance by intervening. Naturally, the car has no idea whether you're at a stop sign and about to climb a steep hill, or whether you're about to go down a steep hill with a stop sign at the bottom. In the first scenario you would want the battery charged as much as possible. But in the second scenario you want it sufficiently discharged to accept all the energy you're about to put in. (I think I might be echoing what you already said.) Since the car doesn't know, it tries to compromise a little so as to be acceptable for either case, which also makes it less than ideal for both cases. That's where the smart driver comes in, who has the ability to properly anticipate the upcoming situation and better adjust for it. And improve mileage as a result.

    "...Running on the battery alone is not a "feature" I would think Honda provided as a benefit. I think it is more likely a loophole in their hybrid control algorithm. If it were a "feature" I think they would advertise it as such..."

    Well I know Toyota advertises that the Prius does it. It seems they think this helps the overall mileage. If follows that the competitor would have also wanted to design in a similar feature.

    "...Now, based on your theory, the battery will charge fully, leaving no place to put the energy gathered by regenerative braking when I stop..."

    No, not really. I didn't mean to imply that it doesn't leave ANY room left. But it doesn't leave much! Mine often continues to charge off and on until NEAR full charge, according to the display. It leaves very little room left for certain situations, like the case I described in post #56 on this board.

    "...I know that the traction motor is used to charge both batteries. There is no separate alternator on this car..."

    Right. But I wonder if the car maybe has a simple DC to DC converter to help recharge the 12V battery with the hybrid battery under such conditions. That would explain the discharge that I saw.
  • "...If you are correct, that would mean that Honda is, well, just plain lying about the product..."

    Well, not really lying. Perhaps they shutdown MOST of the fuel injectors and only leave on enough to be able to continue to idle. Or maybe they drastically limit the fuel to the injectors so that it burns very little fuel while idling. In order to simplify the point, the manufacturer might just say that they shutoff the fuel and consider the difference to be splitting hairs.

    Maybe what I'll do to prove this to myself is wait for cool weather when you can see condensation in the tailpipe exhaust. I can either try to see the exhaust in my sideview mirror (or add a second strategically placed mirror) or have someone follow behind to see if it stops coming out the tailpipe when I idle.
  • albalmaalbalma Posts: 10
    The engine goes off when cruising by on battery power at low speeds, which is confirmed by the engine starting when you depress the pedal to accelerate.
  • kidsidkidsid Posts: 10
    "Perhaps they shutdown MOST of the fuel injectors and only leave on enough to be able to continue to idle. Or maybe they drastically limit the fuel to the injectors so that it burns very little fuel while idling. In order to simplify the point, the manufacturer might just say that they shutoff the fuel and consider the difference to be splitting hairs."

    I would agree that that might be a possibility if it were not for the context in which this information is presented. In the animation I presented earlier, Honda also says that in this mode, the engine's valves remain closed and it's cylinders sealed, to avoid pumping losses. You can't do that if the combustion process is still active,... even just a little bit. So taken as a whole, I would still bet that Honda's description of their engine operation is accurate.

    Here is the animation again. I can find many other examples stating the same:

    http://www.youtube.com/watch?v=xmDkc8SEvwc&feature=related
  • kidsidkidsid Posts: 10
    "(I think I might be echoing what you already said.) "

    Yes, you did but that's ok!

    "Well I know Toyota advertises that the Prius does it. It seems they think this helps the overall mileage. If follows that the competitor would have also wanted to design in a similar feature. "

    I'm not sure that Toyota thinks that this helps the overall mileage. I think that most people who buy hybrids think that the more it operates like a "real" electric vehicle, the better. So it might help sales. As a "feature", it would allow the driver to implement his or her own "clairvoyance feature" as you suggest, but somehow I doubt if Toyota predicted that people would try and operate the car in this manner. (Only techo-geeks like you and me reverse engineer things like this!)

    I've never owned a Prius but I have rented them while traveling or just for fun on many occasions. The only time that I have seen a Prius operate on battery alone was when starting off or going really slow. I think I got a 2006-2009 Prius up to about 18 or 20mph before the ICE came on if you accelerate real gently. Never seen electric only operation any other time.
  • "...Only techo-geeks like you and me reverse engineer things like this!..."

    Well, I hear that you can't spell "geek" without a double E ! ;-)
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