Odd Green Battery/Low MPG Behavior

[jjs357]

I have a 04 Prius with about 41000 miles.

Recently mileage has dropped, measured on the MFD on a per tank basis, 10 to 20%. It seems like the car's ride is rougher than I would expect, especially with new tires.

I am in Philly area and the mileage was lower than normal even with the warm temperatures we have been having. The temperature has changed over the last 2 days -- back to old man winter.

At first I was willing to blame the new tires I installed -- Goodyear Comfortreads. I have the pressures at 42 front and 40 rear.

Over the last two days I made a drive to Washington DC and back to Philly. For the first leg, to DC, I was seeing highway miles at around 45 to 48 mpg. I normally get 51 to 53 on the highway. I kept switching the info display from the bar graph to the instantaneous (moving arrows) display and noticed that the battery was almost always shown as fully green, even when I was accelerating up an incline.

On the way back to Philly, the first leg until I stopped for a rest stop, I was seeing over 52 mpg, even with outside temperatures in the low 30's Fahrenheit. I had filled the tank before I started back. I kept checking the MFD and the battery was almost always in the comfortable blue range as I would expect it to be.

But after the rest stop, I was getting noticibly worse mileage again -- upper 40's mpg at best. And the battery was almost 100% of the time showing green. The only way I could get the battery to blue was to floor the accelerator for a few seconds. Then the battery would drop a bar to the blue range but in a few minutes it was back to green. Mileage stayed depressed almost the entire way home.

BUT, at a stop light, I engaged the parking break and released it -- note that the parking break appeared to be off -- there was no red brake light on the instrument panel, but I was trying to think why the computer was always trying to charge the battery and had a hunch that maybe there was some brake activity being sensed.

After this, until I got home, the battery's charging and color behavior seemed near normal. As I went up a little hill, the battery turned blue again -- the mileage began to creep up.

I am going to see if NOT using the parking brake allows the car's mileage to track more normally. I plan on a trip to the dealer to have them check the braking system.

Anyone experiencing something like this? Does the idea of a partially applied parking brake -- even when the brake indicator light is off -- make sense? Could one of the engine computers be malfunctioning so that the hybrid system is not supporting the gas engine the way it should?

Or is all of this normal behavior?

Thanks for any advice.

[hdrygas]

<div class='quotetop'>QUOTE(jjs357 @ Jan 17 2007, 03:41 AM) [snapback]377089[/snapback]</div>

I have a 04 Prius with about 41000 miles.

Recently mileage has dropped, measured on the MFD on a per tank basis, 10 to 20%. It seems like the car's ride is rougher than I would expect, especially with new tires.

I am in Philly area and the mileage was lower than normal even with the warm temperatures we have been having. The temperature has changed over the last 2 days -- back to old man winter.

At first I was willing to blame the new tires I installed -- Goodyear Comfortreads. I have the pressures at 42 front and 40 rear.

Over the last two days I made a drive to Washington DC and back to Philly. For the first leg, to DC, I was seeing highway miles at around 45 to 48 mpg. I normally get 51 to 53 on the highway. I kept switching the info display from the bar graph to the instantaneous (moving arrows) display and noticed that the battery was almost always shown as fully green, even when I was accelerating up an incline.

On the way back to Philly, the first leg until I stopped for a rest stop, I was seeing over 52 mpg, even with outside temperatures in the low 30's Fahrenheit. I had filled the tank before I started back. I kept checking the MFD and the battery was almost always in the comfortable blue range as I would expect it to be.

But after the rest stop, I was getting noticibly worse mileage again -- upper 40's mpg at best. And the battery was almost 100% of the time showing green. The only way I could get the battery to blue was to floor the accelerator for a few seconds. Then the battery would drop a bar to the blue range but in a few minutes it was back to green. Mileage stayed depressed almost the entire way home.

BUT, at a stop light, I engaged the parking break and released it -- note that the parking break appeared to be off -- there was no red brake light on the instrument panel, but I was trying to think why the computer was always trying to charge the battery and had a hunch that maybe there was some brake activity being sensed.

After this, until I got home, the battery's charging and color behavior seemed near normal. As I went up a little hill, the battery turned blue again -- the mileage began to creep up.

I am going to see if NOT using the parking brake allows the car's mileage to track more normally. I plan on a trip to the dealer to have them check the braking system.

Anyone experiencing something like this? Does the idea of a partially applied parking brake -- even when the brake indicator light is off -- make sense? Could one of the engine computers be malfunctioning so that the hybrid system is not supporting the gas engine the way it should?

Or is all of this normal behavior?

Thanks for any advice.
[/b]

Let us see PA it can get cold there as I recall, but you have had a warm winter at least that is what family in Columbus Ohio and Wash DC tell me and that brackets you. Recently it has gotten shall we say more seasonable. You will defiantly see more green bars when it is cold out. The ICE is trying to first keep warm so it can run efficiently. If you had a temperature gage to look at engine and coolant temperatures you could see a loss of 10-15 degrees F at a stop light! The ICE is also trying to keep you warm as well and if you use the defrost on the front it almost never cuts out in very cold weather. Despite all of that there is some extra energy created by the ICE and it is stored. You will notice that you are almost always sending some energy from the battery to MG2 to drive the car when the battery is full like that. We had a cold snap and on the coldest day I got all green on the MFD going down a long hill that has a 25 mph limit. Your systems are all normal and the car is doing what it was programed to do. I would encouraged you to get a CAN View so you can see better how all this is happening, but that is a sickness and there is no 12 step program! Drive and be happy! Summer will come.

[poodlemaster]

<div class='quotetop'>QUOTE(hdrygas @ Jan 18 2007, 01:18 PM) [snapback]377312[/snapback]</div>

Let us see PA it can get cold there as I recall, but you have had a warm winter at least that is what family in Columbus Ohio and Wash DC tell me and that brackets you. Recently it has gotten shall we say more seasonable. You will defiantly see more green bars when it is cold out. The ICE is trying to first keep warm so it can run efficiently. If you had a temperature gage to look at engine and coolant temperatures you could see a loss of 10-15 degrees F at a stop light! The ICE is also trying to keep you warm as well and if you use the defrost on the front it almost never cuts out in very cold weather. Despite all of that there is some extra energy created by the ICE and it is stored. You will notice that you are almost always sending some energy from the battery to MG2 to drive the car when the battery is full like that. We had a cold snap and on the coldest day I got all green on the MFD going down a long hill that has a 25 mph limit. Your systems are all normal and the car is doing what it was programed to do. I would encouraged you to get a CAN View so you can see better how all this is happening, but that is a sickness and there is no 12 step program! Drive and be happy! Summer will come.
[/b]

sorry, but i disagree. i live in harrisburg, pa, and i drive every kind of road available to flat highways to hilly highways to city traffic to country roads, and i never have green battery for more than 20 seconds while driving and that is when i go down a long hill while i am not using the gas pedal. there must be some sort of problem. definitely have toyota check that out.

[hdrygas]

I bet they tell you it is normal. Check it out anyway can't hurt. Part of it is your driving style and the speeds involved, but I stand by what I wrote you see more green when it is cold out.

[JimN]

jjs357,

I agree with the others that some mpg drop is normal. On my 30+ mile open highway commute I have much more green bar time than most posters and I only drop a couple of blue bars.

Look for the thread "My first day with a blocked grill" (or something close). If you don't see it in "view all recent posts" look for my post today. Blocking the upper grill with the pipe insulation will return 2 mpg and maybe more. Although I completely trust the guys I'm not comfortable blocking the bottom until it gets cold and stays cold. A fan will come on if the engine gets hot. Even at 50 F the engine doesn't get hot with the top grill blocked.

I had very little time in the car when I took a road trip to Indiana at the end of July. After seeing 50+ mpg on the MFD while commuting I was disappointed to get 45mpg on the trip which was all open highway. Keep in mind that even at 45mpg that meant that I didn't NEED to stop for gas until Dayton.

Haven't been to DC in the Prius yet. If you were keeping up with traffic on I-95 your mpg would have dropped. (For those of you outside of the NE Corridor, I-95 is 4 lanes that most drivers use for Indy qualifying trials. The posted limit is 65mph. Realistic speeds are 75+.) When I go you'll find me in the right lane holding up traffic at 65-70mph.

Keep us posted on your progress.

[jendbbay]

<div class='quotetop'>QUOTE(jjs357 @ Jan 17 2007, 06:41 AM) [snapback]377089[/snapback]</div>

Anyone experiencing something like this? Does the idea of a partially applied parking brake -- even when the brake indicator light is off -- make sense? Could one of the engine computers be malfunctioning so that the hybrid system is not supporting the gas engine the way it should?

Or is all of this normal behavior?

Thanks for any advice.
[/b]

I have a new Prius, 2007, Touring, and I recently had the misfortune of it having been run out of gas and then driven on the battery alone to a safe location. Since that time, I have been paying close attention to the way the car drives and to the battery behavior, at least to the extent that I can perceive it from the display.

I have noticed EXACTLY the same behavior, but without the lost MPG. However, we only received 45 MPG before the car ran out of gas, and we now still receive the same, so that part of the story is not comparable.

The part of our story that does relate to your's is that the battery is always fully charged and green and it is really hard to get it to deplete a bit and to look as it did before -- that is blue.

So I am quite interested in how this thread progresses.

[Syclone]

Based on information that I have read, and one instance of a first hand report, Comfort treads will cost you 3 -4 MPG. I couldn't find the LRR list that I had originally seen, but I've attached a report that shows a partial list of tires rated as LRR.

The personal experience that I had on the subject was a friend in the Long Island Prius Owners Group that sold his Integrities and bought Comfort-treads in 195/60/15. He used them for a month and said that he took at least a 4 MPG hit during that time.

I did some research at that time because I didn't like the handling of the the Integrity's, dry or wet. I sold the Integrity's on Ebay and bought a set of Michelin MXV4' plus's in 195/60/15. My fuel mileage improved, even before the surface of the tires "wore in". The car seems more sure-footed, and there is almost no wheel slip when making sharp turns on wet roads (right turns in the U.S.)

http://www.greenseal.org/resources/reports...gresistance.pdf

[toad]

I wonder if it has to do with the terrain. The reason I say this is I drove to Washington DC recently, but from the other direction. I got around 45 MPG driving to DC and around 55 driving back to Richmond VA. I think this is due to the difference in elevation. I think Richmond is lower in elevation than DC. Although I don't know how much of a difference that would make, I think that Philly is even higher in elevation.

In addition, I usually get Green on highway driving and Blue during city driving.

Just a thought.