Prius Stages of Operation & Operating Mode Availability -A Reference Aid

[ksstathead]

Originally Posted by ronhowell

Hi ksstathead and all,

Excellent piece of work; especially in following Winston Churchill's dictum "Pray may I have, on one sheet of paper" - your summary of the details.

The knowledge base on this site is incredible. I have learned more about my Prius in the 5 months I've had it than any other car I have ever owned.

Just one comment with respect to the Hybrid Paradox. While its true that all the car's energy originates from what's in the gas tank, the regenerative electrical energy does re-capture some of the kinetic energy that the gas provides, although with some inherent inefficiency, it is true. To the extent that it is not lost as heat in the brakes, that at least is a net gain.

Time to start implementing your work, no?!

Thanks, Ron!
I concur with your comment; regen is far better than waste heat & brake wear.
Yes, it is high time I purchased. Getting close.

[douglas001001]

You can remove the ? in the shm line under stage 2, it is available but not as effective (in terms of holding speed) until s4 temps with a few miles of at speed transaxle warmup.

Nice work on the writeup!

[Prius 07]

Very nice write-up ... now buy the car and put it into practice

[donee]

Hi All,

Just found this thread.

Are we sure about 73 C for Stage 3 entry? My car seems to do that at 70C, but it has to have both engine/coolant temp gauges at at-least 70 C.

Also, stage 1a end is easily detectable by shallow throttle manipulation. Push just a little, and one gets battery assist. A few seconds later after 1a is complete and one gets battery charge.

There seems to be a more to Stage 3. Maybe an a and b. Stage 3a starts at 70c. If you can keep the car below 75 C (?) it will stay there. Go above 75 and one looses stealth. Then it comes back around 78 C sometimes, 80 C others. Which I take to mean transistion into Stage 4.

I am no expert on these things, and get confused about it allot. But I though I would put in my comments anyway.

A suggestion as to a more concise way to describe these things is a "State Diagram". This would have been how the engineers at Toyota would have mapped it out, most likely. A state diagram would allow multiple methods of stage entry, and even falling out of a stage, to be mapped.

Ambient temp completely changes how these things work. Above 90 F indicated on the Prius outside temp gauge will require a warmer coolant/engine temp for stage 3 entry. Maybe this is where the 73 C comes from? Or maybe its the cat temps that are having an influence too. Had a very confusing drive over to a restraunt this weekend during a hot late morning. Could not get the car to go into stage 3 forever. Engine/coolant temps were up to 80C plus before it would glide. Like it decided to stay in stage 2 until Stage 4 requirements were met. This knocked me down from 67.5 mpg to 66.2 at mid tank, even after a warp neutral 2 mile glide (up to 45 mph), after finally getting into stage 4.

Here is a comment about SHM (super highway mode). I found I need to be above 50 mph, 53 is ideal, and below 55 to get a good SHM going. At that speed, one can get the car going along almost indefinately at 1248 or 1280 rpm on level terrain (although this experiece is possible with the aerodynamic aid of 65 mph cars going by in the middle lane). Downhill decreases the sensitivty of the peddle manipulation to getting into the SHM. The mileage on the Prius display will be in the high 70's to mid 80's when you got it going good. A matching speed side draft with a 45 degree following wind over the draftee will let the rpm drop to as low as 1180 (not sure on those last two numbers) - about as slow as the engine will turn before droping into warp stealth.

I find that 40 to 49 mph is no-man's land for great mileage. Pulse and Warp Stealth is probably the mode of operation there. When I am doing 45 mph in the construction zones, I usually am recharging batteries after running them down from from long uphill pulse and glides in slow and go traffic.

Recent trips have resulted in 3/4's of the 5 minute bars screen being green. Kinda like a good score on that video game with the falling shapes. Ha!

[douglas001001]

donee: I think it might be battery temp which could be causing your weird over 70C experience.

I've been having the same issue lately and hear what I believe to be the battery fan spinning. Opening the window for a block or two and everything is back to normal and the noise I believe to be the battery fan goes away and glides are available.

[kellgy]

Thank you for your solid work. The PDF will be printed and stored in my lower glovebox, he he. This post has influenced my decision to add the EV mod. Great work!

[donee]

Hi Douglas,

I am not hearing the battery fan going. I keep the inside of the car cool with a sun shade, and cracked windows when parked. Which has worked, except one day that was on-and-off rain and sun recently. The mycanscan says the battery temp is under 40C at the end of the drive home. The battery usually starts the morning less than 23 C. I have only used the AC once so far and that was about 3 weeks ago.


I have seen that too-hot battery problem. But usually later in the year, when its over 90 F, when taking the highway route, and not using the AC and during the glides at the end of my evening commutes. I usually use the AC above 90 F, but when its on the edge, I have tried to do without it. Lately its been so windy into my car on the drive home, I have stayed off the highway. Airspeeds of above 90 mph are not conducive to good mileage. The side road is shaded on my nightime commute, and this also baffles the wind a bit.

Engine temps are not going over 92 C, and usaully right around 90 C at the hotest point of the drive home, just before long glides and traffic lights into my neighborhood. After which, the engine temp is down around 86C.

Recently, the 70 C glide oportunity has been very fleeting. The car gets up and through the 70 C glide temp range within a mile from start up, and I do not have glide oportunities that close to my home and work. Uphill in the morning, and stuck in traffic in the evening.

[nyty-nyt]

I have resisted getting a Scangauge, but I try and get the best mileage I can, applying the idea that if I use the brake, I've burned luxury fuel. So far, so good, as I am using only 3.7 liters per hundred K, and nobody following me has given me the finger, or used their horn. Where can I find out about SHM for those of us without the gauge?

Additionally, I find that my car refuses to quench the ICE even though I have six bars, and I am 15 minutes into my commute, unless I accelerate hard (that luxury fuel again) before gliding. Sometimes even that doesn't result in ICE shut-down, until I come to a complete stop at a light, then I'm OK from then on.

Looks like I need that ScanGuage, right? I would like someone to take a stab at why my nice P&G is interrupted that way.

[JimboK]

Originally Posted by nyty-nyt

I have resisted getting a Scangauge, but I try and get the best mileage I can, applying the idea that if I use the brake, I've burned luxury fuel. So far, so good, as I am using only 3.7 liters per hundred K, and nobody following me has given me the finger, or used their horn. Where can I find out about SHM for those of us without the gauge?

Additionally, I find that my car refuses to quench the ICE even though I have six bars, and I am 15 minutes into my commute, unless I accelerate hard (that luxury fuel again) before gliding. Sometimes even that doesn't result in ICE shut-down, until I come to a complete stop at a light, then I'm OK from then on.

Looks like I need that ScanGuage, right? I would like someone to take a stab at why my nice P&G is interrupted that way.

Unfortunately, to nail SHM consistently requires monitoring ignition timing and/or RPM and keeping them within a very narrow range. Without added instrumentation you could try to maintain just enough go-pedal pressure to keep the ICE on. But I have no sense of whether you'll approach the results of those who have the instruments. Here's the full writeup on SHM if you haven't already seen it.

For your ICE non-shutdown issue, sounds like you're still in S3. To move to S4 the car needs to be at a complete stop with the ICE running and sit long enough (generally about 7 seconds) for the ICE to shut off on its own. For that you don't need a ScanGauge. See this for a full description of the warmup stages.

The ScanGauge still is a useful tool for many purposes beyond these.