Confused by the talk about not using the electric motor

I've had mine about two weeks also and I just have fun driving the car. I have played driving in "stealth" mode and its kind of neat when all you hear is the tires on the road. Most of my trips are very short so I'm sure that my millage is suffering a bit (only 46) but its a lot better than what a neighbor gets from his Hummer.

I got mine at Toyota 101 (Redwood City). Where did you get yours?

 

<div class='quotetop'>QUOTE(Tideland Prius\";p=\"99550)</div>

This is a serious question.

If you are neither using the engine or the battery, what is propelling the car?

Also, what do you enter to get the ICE with the line above it?

Well, I just saw the answer to my 2nd question. The software does it.

ICE SKS

 

"Several people say the secret to good mileage is to use the electric engine as little as possible."

Strange! Must not be the same peope who are doing the EV mod.

I drive with the Consumption screen on and let the HSD take care of whether the ICE is needed or not.

 

<div class='quotetop'>QUOTE(popoff\";p=\"99561)</div>

You see, that is the problem with the overly simplified animations. The MFD only shows 1 MG but we know there are actually 2; MG1 & MG2.

When you are coasting or braking, MG2 (50kW) will function as a generator to convert the Kinetic energy to Electrical energy and this will be used to power MG1 (10kW) which now has to act as a motor to reduce the drag caused by ICE and to prevent it from spinning backward. If this regen. is greater than is required, some will go to the battery. If it is less, then battery will need to supply some power. Therefore, the trick is to keep controlling the accelerator to get just the required regen. so that no arrow is flowing to/from the battery. By doing this, you can reduce some efficiency losses from the electircal <-> chemical conversion. Of course when the Kinetic energy is totally converted, you still need to use ICE or battery to propel the car.

Personally, I don't practice this technique as there is too much attention to the MFD and our traffic conditions just make it impossible. I prefer to just drive it and let the computers decide what is best. I find it more relaxing and enjoyable than trying to get high MPG.

Vincent

 

The simple logic is that if you're never charging or draining the battery, you must be driving very smoothly, not braking or accelerating too hard, and relying on momentum. That's good for economy in any car.

The battery exists to help smooth out power demands, provide extra oomph when you need to accelerate, and recapture energy when you brake, for real-life driving.

 

Yep. We want to use the battery sometimes!

When accelerating from a standstill, let the battery do the work. The energy you're using at that point came from times when the ICE was working at relatively high efficiency, and even with the 50% conversion loss, you're doing better with the battery.

There's a long stretch of I-285 I traverse every day on my way home. It's a few miles of very gentle downgrade, and I can generally coast it. When traffic is thick, as it often is on Friday afternoon or if I leave work late, I'm going to be doing a lot of start 'n' stop driving on that piece of my commute. Thanks to the battery, my ICE shuts down for what can be fifteen or even thirty minutes, doing wonders for my gas mileage. On a couple of occasions, that bit of road has tapped my battery completely, and the ICE has to take over, and do double duty moving the car and recharging the battery.

Yeah, the ICE is wonderfully efficient, and the Prius is made even more so by that battery that does things no gasoline engine can possibly achieve. Behind it all are Toyota's marvelous computer algorithms which decide when and how each motor should be employed.

 

The Hybrid Synergy Drive is a wonderful system that allows good performance from a car with a small, weak but thermally efficient atkinson cycle engine. It is designed in such a way that good results can be obtained without any special effort on the part of the driver.

When I bought the car, I regularly saw results in the low to mid 50s with some effort towards driving conservatively. I tried many strategies, including every single strategy that has ever been discussed on this website since it's birth.

With maximum effort, I was able to achieve upper 50s and ranges of 700 miles per tank. These are very good results. I recognize the conversion losses and therefore when trying for maximum mileage, I attempt to minimize these losses when possible. In the other thread, I said, "The better strategy is to use the electric motor as little as possible."

All I mean by this is to recognize the losses and try to avoid them when it is reasonable to do so. I use the electric motor to accelerate at a reasonable rate but I don't ascribe to the strategy of getting to speed very rapidly so that I can start coasting sooner. I don't believe that to be the best use of the system. The losses and substantial use of stored energy that must be replaced will cause a hit down the road and with brisk acceleration the engine will rev faster and will be outside it's most efficient range. Of course these are not absolutes and the faster you accelerate the worse your mileage will be.

Is it necessary to make special considerations when driving this car? Hell no. Just drive it if that is what you are into but if you want to push the envelope, try what I'm saying. There are dozens of strategies to getting the best mileage possible and this only addresses one.

My statement was meant to address those that routinely try to force the car to stay in electric mode. That is actually slower and less efficient that using the engine in it's most efficient range. When done "as often as possible" the battery is run to a low SOC and the subsequent miles will be at a lower MPG than if the system was not charging the battery back up to it's optimum level. With 2 to 4 bars on the battery monitor, your mileage can't be as good as it would be with 6 bars.

My recent tanks have been a testimony to the accuracy of my statements. My last two tanks were 729 miles at 60.7 MPG and 768 at 61.8 MPG. My current tank is at 324 miles and 63 MPG. My commute includes about half the miles at 60-65 mph and I routinely exceed that on the downhills. If I had a commute where the speeds didn't exceed 45 mph and was the same length as my current one the mileage would be around 70 MPG.

Does it matter? Only to me. The amount of gas saved between 50 MPG and 60 MPG is about 20 cents per hour in gas savings. It's just for fun ya'll.

If it really isn't your cup of tea then just drive it and enjoy the best car ever designed for our current needs and future reality.

And as always, Your Mileage May Vary.

 

OK Ray,
I'm sold. Quick questions. What tires and pressure are you using? How many miles on your car?
Thanks...

 

33,000 miles on the car. OEM tires at 42/40. Three quarts of Mobil1 in the crankcase. I'll be replacing the tires soon. They still have even tread wear even though I've only rotated them once and they just passed state inspection but they're getting a little squeely around corners. I'll wait maybe another 2,000 miles. I may replace them with another set of Integritys since I haven't found anyone being thrilled with the alternatives. OK maybe some glowing reports on the Goodyear TTs.

 

I try for max battery use. But I read these comments and what Evan describes doesn't sound all that different to me from what I do.

But I don't exactly see how anyone drives with ICE only? My car goes into battery mode on it's own regularly whenever it feels like it whether I try for it or not! When I try for max battery I am only trying to aid the car in deciding when to do it.

For example, If I am at enough speed and on level road I might feather the pedal to help trigger battery mode, when I know the car will be soon going downhill and be able to stay in that mode for a while. If an uphill section was ahead I would not do this.

I think of my method more as trying to minimize engine start stop cycling, but also avoiding situations like a low battery when stopped at a long traffic light where the engine would run just for battery charging.

 

<div class='quotetop'>QUOTE(\"tomdeimos\";p=\"99809\")</div>

This is really a hard subject to quantify because of all the variables. When we try to state it simply, it is easy to misinterpret the meaning of our statements.

I agree that it is helpful to feather the peddle to avoid Ice start but only to a point. It is even better to coast without engine or electric motor. If the car needs a significant amount of motive force, it is most efficient for this to come from the Ice. What we are really referring to here is the practice of trying to drive as much as possible with the energy from the battery. When you run the battery down trying to nurse the car along without the engine for as long as possible, you will not achieve maximum efficiency.

When you use the electric motor only but are not drawing much energy from the battery then it is similar to no arrows operation. I am only concerned with drawing down the battery significantly.

The best mileage I can get would come from using the engine to get up to around 45 mph and then coast in neutral to around 35 and then repeat the cycle. But again, all the variables like terrain and AC use can alter this a bit. I this was continued for a long distance, the average MPG would be in the 70-80 MPG range. I'm talking near test track conditions. Lots of things can impact these results, such as road surface, wind, temperature, and even dewpoint. Yes, our cars get better mileage in high humid conditions. Pilots are familiar with altitude density that relates to the density of the air. Hot humid air is less dense and offers less wind resistance.

At the level of mileage that I am at, things like a 5 mph headwind or tailwind can change a leg MPG from 72 MPG to 67 MPG. I'm recording individual legs of this tank. I live 600 feet higher than I work. I see morning legs ranging from 66-72 MPG and afternoon legs ranging from 55-58 MPG. This commute is 30 to 31 miles one way depending on the route I choose.

 

Evan- Yeah I hear good comments about the Hydroedge on handling but at a mileage and noise cost. Have you been rotating your tires? Not long ago, you reported even wear didn't you? Has this changed recently?

 

<div class='quotetop'>QUOTE(Ray Moore\";p=\"99830)</div>

I agree about it being hard to state things simply without them sounding misleading even when I read my own words back again. But I'm beginning to get the impression we are approaching some similar techniques, but from opposite directions. And it would be great to be able to test some things out on a fixed track with no other traffic and no wind, and indoors so we could set the temperature too!

The car makes it really easy to measure things. But deciding what change of many caused the major mpg changes can be difficult.

And the car really has a mind of it's own sometimes. I get different amounts of battery mode on different days for reasons I can't figure. And around here temperatures are always fluctuating and mucking up the numbers. When it gets cold here the battery just shuts off! The car does different things below 50 degrees than above 70 degrees.

I am beginning to think the car has some memory about things the driver does. For instance when I use the EV button, it seems to make the engine cycle to battery on it's own more often. Coasting more often seems to also have this more lasting effect. I would not be surprised at all if the cars adjust somewhat to the slow accelerators, and then some other way for the brisk accelerators.

And conditions are very different in different locations. For instance when I talk about running on battery as much as possible, or accelerating using battery at certain times, it never occurred to me this might be read as trying to go 7 green to 2 pink bars in a cycle. Around here I couldn't do this if I wanted to, since there is always a little hill coming up that is enough to make the engine start up. I do use my EV button but I don't use it to push the battery further than the car does on it's own.

I get 2 pink bars only when I park and want to run the AC. In driving with my max battery usage, the bars generally cycle 6 bars to 5, or in cold weather 7 bars to 6. Sometimes I might see it jump up and down by 2 bars.

 

On a very simplistic basis, would it be safe to say, that the best driving strategy would be one that would maximize green or no arrows on the MFD?