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Anyone play around with stage 1a on a Prius. This is where you start the car and leave it in park for about a minute till the engine cuts out. This burns about 1.3 oz of gas but does 3 things:


Heats the Engine
Charges the battery
Enables EV


What struck me when I tried it is that the RPMs are at about 1200 but the load is over 70%. That is definitely not an idle... that is a lot of charge going directly to the battery. Normally while driving in S1 the LOD is 30% (idle load) so I doubt anything is really getting to the battery. Plus in S1 the battery is usually getting drained by driving. My standard NICE-on S1 transition consumes the bar 4 leave me with SoC of 3.

So by my math, just driving through S1 with NICE-on has your RPMs at 1200 the whole time, and consumes on bar of SoC. By parking through S1, our at 1200 RPM but gain you a bar of SoC.

I'll be trying it and reporting numbers to daily grind.

Any thoughts?

11011011

Hi Dan:

___I cannot directly correlate your thoughts with what I am driving currently but the warm up hit can be taken out of the equation in the NHW11 to some degree with a few for real FAS’ all the way to a stop. She has a key ;) I have to shut her down completely and restart after the stop but I am stopped anyway … With this method of warm-up I used this morning, the SoC kept climbing to full (only half and full in the NHW11) while the ICE was running and by the time she touched 159 or so, her SoC appeared to peak and I was > 60 mpg’s. It was nice to see > 45 after her first pulse out of the lot vs. mid 30’s the previous few days which was really pissing me off :angry: Letting her run in that forced charge mode would not allow me to see but the low to mid 40’s on the same 2 mile segment I saw 60 + this morning on. This was while that hard idle charge was occurring between 1200 - 1300 RPM while stopped or in a simulated glide.

___I do not know if this helps you or not wrt the Prius-II? This Prius-I is starting to show me her secrets and I am not only excited but trying to take advantage of them at every opportunity given the limited time I have left with her.

___On a similar note, I believe the Japanese Prius hypermilers let them idle to S2 or S3 before taking off IIRC but I cannot stand watching an ICE rev away doing nothing but somewhat inefficiently charging a pack or doing nothing at all :(

___Good Luck

___Wayne

Dan,

I'll be interested to hear about any testing you do comparing the "parking S1" vs. "driving S1".

My commute in now involves 1.5 miles downhill of ICE-off to start the day. The downhill ends with a stop sign. When I light the ICE at the stop, her temps have fallen and she really wants to assist for 15-20 seconds. I don't really like it, as the assist really consumes SOC.

I've tried other techniques to avoid that assist:

(1) lighting the ICE on the last 15-20 seconds of the downhill
(2) Maintaining 5-10mph after the stop to avoid assist
(3) Doing rather quick accel + backing off regen to avoid assist loss

All of these methods get me worse numbers. My best numbers over the first 5-7 minutes are when I get up to speed with the battery assisting. As a result, that's what I do. I just make sure I have 6 bars to start, so that I can be left with a tolerable 4 once I've warmed up.

I'd rather this not be the best, cause I hate the assist. Did I mention I hate the assist? :)

Holy cow!

Took my son to the pool and on the return trip I did stage 1 through park on the way home.

1.2 mi @ 61.5 mpg @ 85 ºF = :eek:

WT at ignition was 120 ºF (50 ºC). And here's the amazing part. I started a 4 bars SoC and ended at 4 bars SoC. First test is pretty darn convincing.

11011011

___On a similar note, I believe the Japanese Prius hypermilers let them idle to S2 or S3 before taking off IIRC but I cannot stand watching an ICE rev away doing nothing but somewhat inefficiently charging a pack or doing nothing at all :(
My thoughts too, but when I saw 70% LOD at 1200 RPM while in Park it made me really think twice. That's (if I'm right) smack dab in it's low RPM power curve. I agree that round-trip energy cycle from engine (mechanical) to battery (chemical) back to the wheels (mechanical) has a very high loss rate.

Problem is SKS equiped PII can't FAS (power button is disabled at speed). So you either completely waist the S1 ice cycles through NICE-on while cannibalizing SoC, or you harness it (if only a fraction of it) through S1a progression where you can P&G without using any SoC for assist like S1 is so horrid at.

Since PI allows FAS, this really turns into a PII only question. Possibly Camry and other HSDs, but I can't speak to that.

11011011

Anyone play around with stage 1a on a Prius. This is where you start the car and leave it in park for about a minute till the engine cuts out. This burns about 1.3 oz of gas but does 3 things:


Heats the Engine
Charges the battery
Enables EV

And a fourth: heats the catalytic converter. That, as I understand it, is its S1 priority.

As you've seen and as the 5 stages paper (http://techno-fandom.org/~hobbit/cars/five-stages.txt) describes, the car is reluctant to use the ICE for propulsion during S1. When it sits, of course, it will charge the battery, but most propulsion will come from MG1 & MG2 until S2.

Sorta like Wayne, I hate to just sit and let it run. From my fiancee's house it's not a problem. Her 500' driveway starts level and gradually turns slightly downhill, and with a pre-warmed ICE it will generally be at S2 when I turn onto the main road, with minimal battery drain along the way. In fact, when I get a little momentum I put her in neutral until I get to the end. (After the EV button install, S1 is about the only time I use NICE-on anymore.) I could EV it down the driveway, but the main road is 45 MPH, moderately busy during rush hour, and is uphill for the first quarter mile or so. I've tried that and I really drain the battery trying to get it up to speed going up that hill. That costs me a short distance later when I can make better use of EV mode during S3 glides.

Then there's my landlady's house. There I let it sit until it reaches S2. Her 1/4 mile driveway is mostly uphill, and the first segment is particularly steep. If I try to move right away, that too puts substantial drain on the battery and I once again would pay the price a short time later. These days with the warm ambient temps and the block heater, it runs only for about 30 seconds or so.