Starting the car

You can't change this...the engine needs to warm up for maximum emissions and running efficency. It helps over the long run but kills you on short trips.

 

if you want to get out of the driveway electrically, back out. while the engine may be recharging the propulsion battery, it's not providing motive power to move the car in reverse. reverse it always totally electric.

other than that, if you use EV mode "to save on gas", you probably won't win that battle... the ICE will only have to recharge the battery later, and unless you can get the recharging to be done only during downhill runs, the net will be less efficiency due to conversion losses through the generator and battery themselves, after the efficiencies of the ICE are accounted for.

as someone once recommended to me, after about 600 miles, "drive it like you stole it."

 

I imagine it is best the way it is. Isn't it easier on the ICE to warm up on a city street at 25 mph than screaming down the highway at 70? It's going to do it at some point anyway. Be nice to your ICE

 

Actually, forward or reverse, the electric motor is (primarily) propelling you during the warm up process.

Even though the engine is running, it generally is not providing the propulsion. Unless you really gun it, you will notice the RPM's do not vary by much until the vehicle warms. The engine is running at a speed that minimizes emissions until the engine and catalytic converter warm up.

 

i back out of my driveway and the ICE still comes on within about 10 seconds no matter what im doing. in fact, it seems to run more in reverse than forward.

and i agree that the ICE comes on because its necessary. trying circumvent its operation could be detrimental to your battery pack and it may take months or even years before you realize that.

with no long term data on the longevity of the battery pack, this is all speculation. up until i got my Prius, i had never heard of a battery that thrives on never being full charged. after all, i know that lead acid batteries last much longer if kept at full charge and Ni-Cads are notorious for "charge memory"

but lets face it, the estimated life of the battery pack if maintained in a SOC ranging from 40-80% is astounding imho. of course, this all adds to the uphill climb the Prius has had to make. (still battling the "plug-in" hurdles with some people i encounter)

its too bad that it will be several years before we have any concrete evidence.

as far as the motive force being nearly all EV during warmup, i have to dispute that. according to the display its not and i dont feel that it is either. i have become quite good (as im sure others have) at knowing what mode my Prius is in without looking at anything. I can feel it when the ICE comes on because the transition is obvious to me even under the mildest acceleration.

i am on the city streets at 4:30 every morning. there is no traffic to speak of ( i average seeing about 2-4 other cars A WEEK) so i purposely take it slow and easy since its just over a mile to the freeway and i want to minimize "freeway shock" on my baby. even at speeds of 15-25 mph, i cant stay out of ICE operation for motive force.

if i think of it, i can get a screen shot showing nothing but regen from the wheels to the battery and the screen still showing mpg of 35 mpg or less. that tells me that the car warming up in the morning is providing a vital service to the car. remember that the Prius uses an electric heater to warm up the water for the engine instead of hot exhaust.

keep in mind that this is all happening when the morning temps are only 50-60º F. im sure that this pattern will intensify when winter rolls around. i have been comtemplating taking surface streets to the next exit (about 3 miles) down before getting on the freeway as opposed to warming up the car by idling on real cold days. but we will cross that bridge if and when the time comes. the air conditioning works very fast at start up. i havent had the opportunity or desire to see how fast the heat works although i have read several posts that tells me it shouldnt be too much of a concern.

 

Makes sense now!

Thanks! Now I think I understand my car's behavior at startup. I FEEL the ICE come on within 10-20 seconds of starting the car but it frequently DOESN'T show up as charging the battery or accelerating the car on the energy display. I just see the awful MPG readout. Then, after a short time, the ICE shuts off and from that point on it shows up normally on the energy display when it runs and shuts off. There must be some short term independent control of the ICE that activates at the time of a cold start based on its temperature. This function is apparently not visualized on the energy display. Does this make sense?

 

yes it does. how else could regen only mode result in something less than 99.9 mpg when supposedly i am generating power? the answer is simple, when warming up, the ICE is not running in its normal mode. things like the heater warming up the engine (amongst other unknown processes) takes a considerable amount of the resources available.

this goes a long way towards explaining why the first bar or two is always much lower than the rest of the bars. currently for me, its usually just the first bar that is in the 20-35 mpg range. every once in a while its the first two bars. i expect this to change to 2-3 bars in the winter simply from the colder outside air.

keep in mind that a regular ICE generates more heat than is necessary to keep the engine warm after it has reached its warm up point. the Prius because the ICE can run as little as 50% of the time, might on colder days, not be able to remain in the optimum operating temperature resulting in more hig demand conditions as described above.

another thing to check out... when the car is warm, even if i floor it, the lowest mpg reading i can manage is usually about 11.2 mpg...according to the car and driver tests in another post, the Prius was run at full speed around a closed circuit race track and averaged 18-19 mpg.

BUT in the morning under nearly non existent acceleration i can get as low as 5-6 mpg.

 

ok i im referring to the water heater or the manifold heater or what ever it is that is using all the power during warm up because is sure aint what the car says it is.

also do you know what "speculation" means?

 

the first 5 minute block is always lower as the ICE tries to get the cat's up to temp and this is not a fast process as the ceramic substrate used in them is slow to warm thru. As such the two O2 sensors keep the computer informed of the internal temp and when they are sufficently warmed then the computer tells the ICE to shut down, assuming stage 4 is reached, if not it will keep running. The engine will reach 70C in about 4 minutes from cold according to the miniscanner in my 2k3, which dosen't have the benifit of the thermos. One day I'll program into it the O2 outputs and see what the readings/time readings from them.

 

ok so you are saying that the warm up period would be the same even in cold weather?

that would be good to know. as it is, the mpg will take a hit because of the watered down winter gas mix.

 

no it will take longer in cold weather than in the summer time, how much longer I don't know but it will. You have to bring the mass of the entire engine up to 70C, so if you start at 2C it's got to take longer than if you start at 15C. You can't refute the laws of physics.

 

I think you will find MRT has plenty of data. They have had hybrid and elevtric busses (for example) in Japan for many years. I think I read on www.toyota.co.pj that they have been producing hybrid busses sicne 1986.

 

Dave: Two points:

The reason you can see regen AND low mileage during warm-up is simple: The ICE continues to run until it reaches a set temperature, therefore you are burning gas. Any time you slow down you are regenerating. But since you are burning gas while you move, you see the low mpg figures. Ergo, regen and low mileage at the same time.

Second point: in Washington State it NEVER gets all that cold. By the time you've driven a mile on city streets your car is plenty warm to handle freeway speeds. Even at 30 degrees below zero, the system is in S3 operation after about 2 miles, and would be able to safely put out maximum power long before that. How often does it get that cold where you live?

The great thing about this car (pardon, one of the many great things) is that if the ICE is not warm enough to produce full power safely, it will draw more power from the battery.

The advice around here for conventional cars (which don't have that safety margin) is to drive slowly for 2 or 3 minutes before hitting highway speeds in winter. In WA your car is ready to drag race after one minute.

 

how can you see the RPM's ? My instrumentpanel does not show it, one of the few minus points on this car...... :roll:

 

actually on the battery packs it could make sense if the battery packs were in a 2004 Prius.

the battery pack reliability in a bus, i wouldn't take with a grain of salt.

who cares how the batteries stand up in another application? i sure dont. i want to know how it stands up in a car like mine. Even the 2003 is different than the 2004 and as i have said before it aint the battery, its the computer controlling the battery.

i have every confidence in toyota's engineering... but i also have their warantee...

 

You'd have to install a tachometer yourself. I'm pretty sure Toyota didn't include one because it wouldn't mean much to anything over than the most information-needing driver. Since the Prius can be propelled by just the engine, by just the motor, or by both, a tachometer would never really show the full picture. And since the pedal is electronic, you have no manual control over the engine, so the RPMs could be all over the place, depending on when the computer decides the engine needs to rev...and it wouldn't necessarily even be going all to the wheels.

So yeah, Toyota wouldn't put in a tachometer when the readings on it were going to be so different from another car. It could easily scare people! :mrgreen: