[dshanz]

Whenever I'm at a standstill and apply gas, however lightly, the gas engine kicks in immediately. I've only got 600 miles on it but my average in-city mileage is only 35 mpg. (I'll be taking it back to the dealer on Monday, but I thought there might be a quick-fix or perhaps I'm doing something wrong. Or maybe the "idle" is set too low? Or maybe there's a break-in period? Beats me...

One last thing: On the display that indicates the power source, the battery never tops off, nor does the indicator turn green (a pal told me that the battery icon turns green when it's "full")

Anyone have any thoughts or suggestions?

Thanks,
Dan S.

 

[ehurtley]

Whenever I'm at a standstill and apply gas, however lightly, the gas engine kicks in immediately. I've only got 600 miles on it but my average in-city mileage is only 35 mpg. (I'll be taking it back to the dealer on Monday, but I thought there might be a quick-fix or perhaps I'm doing something wrong. Or maybe the "idle" is set too low? Or maybe there's a break-in period? Beats me...

One last thing: On the display that indicates the power source, the battery never tops off, nor does the indicator turn green (a pal told me that the battery icon turns green when it's "full")

Anyone have any thoughts or suggestions?

Thanks,
Dan S.

It takes a *LOT* to completely fill up the battery. In my case, it took going downhill for about twenty minutes, riding the 'brake' the whole way, to get it full for the first time.

And from what I can tell, when you first turn it on, it prefers to use the gas engine so it warms up. Once you have been driving for a while, and the ICE is warmed up, you will be able to drive on electric alone for more extended periods. (For example, leaving my house, I can't even make it 1/4 mile without the ICE kicking in, but coming home, when I've been driving for almost half an hour already, I can make the final 2 miles on electric power only. Over mostly level terrain, with only one hill, that I have to go both up and down no matter which direction I'm going.)

 

[hudel]

Dahanz,

Like you I also have only a few hundred miles. And I also had the same concerns.

Currently I am getting about 43 mph city, and 51 mph highway (47 mph average). But as pointed out by ehurley the need of the gas engine seems to vary based on how recently the car was run.
:?

 

[BIF]

If your AC is on max, I think it's possible that your engine will only "auto stop" at traffic lights.

Check this, and experiment with turning the AC to "low" or dialing up a warmer temperature if you're using "auto."

Try it also with the AC off, and see if the behavior is different. At least you'll have more to tell your dealer.

 

[Kev1000000]

yea, until the car reaches stage 3 or even 4, you wont be going in stealth mode too much, if not at all.

The car likes to warm up the ICE for awhile, usually the first 5 minutes of driving. Then after that, the car likes to use the electric engine a lot, and you can provoke the car to go into electric mode by letting go of the gas and then feathering it.

I usually cruise up to about 5mph over the speed limit in the city then try to provoke electric mode which will slowly make my way to the speed limit on most roads here in the city (40mph)

 

[hyperion]

I too believe you will find less use of the gas engine when the weather turns cooler and you get your AC out of auto. The ac pulls the battery down quite fast and the engine makes an effort to keep up with it. My milage was much better this past winter.

 

[dshanz]

Thanks everyone. It's hot in North Carolina so the AC may be the problem. I'll run it this weekend without AC and see if it makes a difference...

 

[Daniel]

It also depends how hard you step on the pedal. Assuming the car is fully warmed up, if you touch the pedal gently enough you can move in electric mode. But you'll have the drivers behind you very angry that you are accelerating so slowly, and your mileage will not be as good. If you step on the pedal hard enough to go with the flow of traffic, the ICE will come on almost immediately. Later, when you are cruising at speed and the power demand is lower, the car will sometimes switch to electric mode. You can encourage that to happen by "feathering" the pedal, but the car will do it even if you just drive normally.

Contrary to popular hype, the car is not intended to accelerate from a stop in electric mode.

NiMH batteries last a LOT longer if they are operated within a very narrow range of charge. Under normal operation on flat terrain you will seldom see more than 6 or less than 3 bars; and the full 8 bars is still only about 80% of the battery's capacity; and zero bars is around 25%. That's how Toyota keeps these batteries lasting for the life of the car.

 

[jshore]

I've had my Prius for 2 months and am getting about 50-52 mpg in the city. Most of my commutes are about 15-20 minutes. In the first 5 minutes, the MPG is only about 25-30 because the gas engine wants to be on a lot. (You have to remember that the Prius is not only a high mileage car but also a very "clean" car with very low tailpipe emissions of NOx and SO2 and such...and in order for this to be so, the engine has to run to warm itself and the catalytic converter up.) Usually, it is only after at least 5 or even 10 minutes that I am able to run significantly in electric. I was originally trying to accelerate from a stop using only electric but gave up on this...unless I am only accelerating to a very low speed...and focus instead on trying to switch to electric once I get up to speed (assuming that speed is still low enough to allow for the electric to run it).

I haven't noticed a dramatic difference in being able to go into all-electric mode with the A/C on. But, since Rochester is pretty cool...especially this summer, I've been able to run a lot without A/C and rarely have had to turn it on very high. (E.g., typically the outside temp will be 80-86 and I'll set the climate control to 78 degrees.)

 

[BIF]

...and zero bars is around 25%....

I thought "zero bars" could be anywhere from zero to 40% SOC. Have you learned something that the rest of us don't know yet? Thanks.

 

[BIF]

I have found that with a very gentle "push" on the pedal, I can get started in electric mode, and even get a good 20 feet or so before the ICE starts up.

I don't get the "middle finger of friendship" from people behind me at traffic lights, so I know I'm not starting off too slowly.

I think this does help with gas mileage, because I've saved the ICE from being responsible for that zero-to-eight-ish MPH accelleration, which is second to idling in fuel wastefulness.

But please note that this only works when the battery display shows more than 50%, and if my AC is either off or on low.

Even on hot days here in Florida, I can often get away with running the AC on "auto" and at 79 or 80 degrees. That usually works out to "low" on my car's climate display.

 

[Daniel]

BIF:

I'm just going by what I've read on this and other Prius boards. What I've read is that zero bars is 25% of battery capacity, and that, with the possible exception of very extreme circumstances (?), the computer will not let the battery go below that. (For considerations of battery life: you are deprived of about half the battery's physical capacity, and in return your battery will last the life of the car.)

I do not have the link at hand, but I read a fascinating description of what happens when you accelerate from a stop. (Possibly from Graham's site.) Basically it's like this:

As you start out, the ICE is spinning but the wheels are not, so the torque the ICE applies to the wheels results in no power transfer. The ICE turns MG1 instead, which gives electricity to MG2, which turns the wheels. Depending on how hard you press the pedal, additional power may be drawn from the battery for MG2. As you begin to move, more power from the ICE goes directly to the wheels, and less goes through MG1 to MG2. Note that the ICE can be turning at a relatively constant rate the whole time, keeping it within an efficient range. The faster you go, the more power is transfered directly from the ICE to the wheels, and the less goes through MG1. Once you reach a constant speed and the power requirement to move the car is minimal, the power going to MG1 can be used to recharge the battery instead of going to MG2 to help drive the car; or the ICE can shut off entirely and the car can be powered by MG2 directly from the battery, until the SOC drops to where the car starts the ICE to re-charge the battery. The torque from the ICE is always split at a constant ratio between the wheels and MG1 (60:40 ?????) but the relative speeds of the different components determine the ratio of the power delivered on the two different paths.

It is true that there are losses due to inefficiency whenever you convert mechanical energy to electric, or back, so the path ICE-MG1-MG2 involves inherent losses. However these losses are dwarfed by the gain in efficiency from allowing the ICE to always run closer to its design rpm.

You are not improving things when you accelerate on electric, because then all your acceleration energy comes from the battery and encounters the conversion loss. If you accelerate normally, allowing the ICE to run, then some of your acceleration energy is direct mechanical transfer from the ICE to the wheels once the car has begun moving.

This explains John's recommendation (supported by others) to accelerate using the ICE, and only try for electric after you are up to speed. In other words, "Just drive it!". Exactly the same techniques for improving mileage work for the Prius as for other cars: moderation: don't abuse it, but don't baby it.