New Prius - "Super Highway Mode" Technique (SHM).

[philmcneal]

damn and i wrote bta as battery voltage -_-; can you make sure its the right code since i don't want to challenge your disclaimer :P

[hobbit]

Battery current bobbles an amp or two in either direction when
you're at 60% SOC and not making any specific demands, and doesn't
have a whole lot to do with how efficiently the engine is running.
You'd be much better off watching injector time and keeping it
in the fives.
.
_H*

[Dan]

Confirmed!

Originally Posted by Dan

For the 75mpg segments I'd try to seek TPS of 17 by holding GPS at 16 while gliding down from 56 mph to some lower speed. After the SOC is around 61 percent, if you hold GPS at 16 for 7-10 seconds you will see TPS drop to 17 and MPG hit 90+. You will also feel a little boost in power output when TPS drops like a semi just put you in it's slipstream.

I started watching BTA in SHM and your right.. SHM puts BTA at darn near zero when you've got it cornered.

The "boost" you feel in SHM after holding for 7-10 seconds is the release of forced regen into the battery. Using my bta gauge I see BTA drop from the +7 to +10 amps (regen) range to a -4 to +4 amp range. That 10amp regen is dragging the engine causing extra fuel burn and quicker decel. It releases after 7-10 seconds and the regen seems in equilibrium. It bounces back and forth. If you have the passive XGauge bta gauge, you will see it flicker from regen to assist to regen a dozen times a second. This is the sweet spot.

Hobbit was right earlier though. This mode is simply the efficient low band RPM in the prius. I'm not as convinced that there is some Atkinson magic here.

Originally Posted by Dan

Found a fun new SHM game in the Prius.

Trying to fix the "bta" XGauge, I finally just gave up and decided to live with the scaling being off by a factor of 160. The result was kinda cool...

WARNING: the gauge is in the car, coding from memory....

bta
0x0033
0x0100823B0000
0x1410
0x000100010000

Now the only thing to really watch is the negative sign. When the bta number is negative your in regen, when it's absent your in assist.

So here's the game, bring up the FU'd bta gauge above and get up to around 40-50 mph.

Now ease off the gas (gps XGauge) until the negative sign twinkles. The idea is to get right on the border of the point where the engine can't decide whether to assist or regen. Once you find it the neg sign will start blinking madly. This turns out to also yield a real good FE steady state. The higher your SOC the higher your steady state speed.

I've noticed that bta twinkles when in SHM so I decided to see if twinkling bta was enough to get good FE... it's pretty close. Now full SHM doesn't really happen till your at a good high SOC, but this is a good way to get some of the SHM P&G benefits while your building up your SOC.

Without going into SHM you can find a type of sliding scale here based on the passive-can bta XGauge, and the passive-can gps XGauge. Once you hit your top speed, slowly let off the gas (dropping gps by 1.0 at a time). Eventually, you will see bta drop below 1000 (6.3 amps). Soon after that you will see the "-" sign twinkle on/off a few dozen times per second. When this happens, hold throttle keeping your gps number constant. This is usually good for very long sustainable 70 mpg coasts. This spot seems to show up again at the right speed in the 90 mpg range.

Finally think I figured this thing out!

11011011

[Right Lane Cruiser]

That's pretty awesome, Dan! I'm amazed by what you've been able to discover about the Prius.

[hobbit]

I can just see trying to explain to Joe Toothless how you need
to hold your twinkling beady-A and let the terrain be your
master. He might pick up on the "twinkie" part if he's on the
ball, but that's about it...
.
_H*

[diamondlarry]

I would like to confirm Dan's observations relating to gps/IGN17. I had a long trip to Akron, OH and back several months ago so I had a lot of time for observation. Without having read Dan's previous posts about this series of conditions, I started noticing a pattern after a couple of hours: Get up to ~55mph and slowly let off gas until gps hit 16.5 or below, IGN hits 17, and mpg goes to 90+. The lower speed limit for this condition seems to be about 45mph. I also noticed that you can keep IGN17 if gps goes to 17. If gps goes above 17 for more than ~10 seconds, IGN will jump to 18 and mpg drops to the 70mpg range and you will have to start all over again.

[Dan]

Started a new Super Highway Mode Revisited thread where I think I have the mystery solved...

Originally Posted by Dan

A few years ago Wayne tipped me off to some really nice behavior on the Prius at low RPM. We've been able to replicated fairly regularly with the following recipe and SG gauges (TPS, IGN, SOC, RPM):

1. Do highspeed P&G with Warp Stealth until SOC is 61% or higher.
2. Ensure that block temp is over 165 degF (70 c).
3. Switch to CONSUMPTION on the MFD (castle display) to watch the instant MPG bar.
4. Get up to a speed of about 62-65 mph.
5. Now slowly ease off the gas pedal until you can hold a reading of 14 on IGN and 18 on TPS.
6. You should see your MPG bar at something between 75-85 MPG.
7. Hold this pedal position for 7 seconds and you should see TPS drop from 18 to 17.
8. Once TPS drops you should see the MPG bar jump to 85-95 mpg range.
9. Hold this "SHM" glide for a long as you can, then go back to step 4.

This much we know, and it is well established. The bit of mystery is "What exactly happens in 7 and 8, and why?"

Well the answer revealed itself...

11011011