HSD behaviour during S1a & S1b warming stages

Discussion in 'Gen 3 Prius Technical Discussion' started by FrankTiger, Jan 21, 2012.

  1. FrankTiger

    FrankTiger Member

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    Hi Everyone

    My car is 2010 european specs Prius. I am recording about 100 different PIDS with my own ELM327 datalogger since the summer of 2011. Earlier I used the freeware OBDGauge to record more than a year of Prius operation.

    In this thread I will show you the HSD behaviour during S1a and S1b warming stages recorded in 27 different trips. In all the warmings, the ICE does not work for the car movement because the car is stationary or manouvering to leave a parking space in a deep basement parking lot in which temperatures do not follow outdoors temperatures. That is the reason because lowest coolant initial temperature is 9ºC (48ºF) In all the warmings but one, the initial SoC is below 50%. As many of you know EV cannot be selected below 50% SoC. I always try to use EV in this indoors parking lot.

    The first graphic is the plot of the ICE running time and the gasoline burnt volume versus the initial coolant temperature.

    [​IMG]

    Click here for zoom in

    In the dark curve, which is read on the left vertical axis, you may see the ICE running seconds until the warming cycle (S1a&S1b) is done. On the pink curve (read on the right vertical axis) you may see the gasoline volume burnt by the ICE during those seconds. The linear equations tell us that every centigrade degree below 28ºC of initial coolant temperature costs about 4.5 ICE running seconds and 2.8 ml of gasoline.

    Using the above equations; the cold effect on tires of this post http://priuschat.com/forums/gen-iii...6-cold-weather-effects-tires.html#post1454758 ; the cold effect on transmission friction (in a future post); and the difference in ICE efficiency due to ambient temperature (in a future post) we can make a theoretical table of the effect on fuel economy by the combined effect of warming, ICE efficiency and increased resistance for lower tempeatures:

    Sorry. This table is unfinished yet. Please wait for future posts about variations in transmission resistance and ICE efficiency with ambient temperature


    You are going to see a lot of charts for the warming process during S1a and S1b stages. Please notice that the horizontal axis is time and spans for 3 minutes. The parameter readings are taken every 0.8 seconds, so I believe that the curves are accurate enough. All the charts use metrical units (ºC and mililiters). If you are interested, please let me know and I will post some of them in US units.

    First chart represents ICE RPM versus time for every warming-up. The initial coolant temperature is marked on the relevant curve.

    [​IMG]

    Click here for zoom in

    The comment of the chart printed on the big arrow refers to the first chart where time and burnt gasoline is plotted versus initial coolant temperature. You may notice that the 39ºC curve is very close to the 27ºC curve and is because after 55 seconds of engine running (end of S1a) the coolant temperatures reach 40ºC when initial temperature is 28ºC or above, so the curves for all these temperatures are almost the same.

    You may notice that ICE RPMs have some oscillations around 1280 a few seconds before ICE stops.

    The following chart is the coolant temperature chart. You will see that all curves, but the one of 39ºC, stop climbing when they reach 40ºC which is the triggering event for the end of S1b warming stage and ICE stops.

    [​IMG]

    Click here for zoom in

    Next chart is the fuel flow (measured in mililiters/second) during these 3 first minutes:

    [​IMG]

    Click here for zoom in

    Most of the fuel flow curves are very close during the first 50 seconds, except the one for coolant initial temperature of 39ºC which is lower than the bulk of them. The pattern for the curve of cold temperatures warming seems to be a soft descent from values of 0.80ml/sec (at 10 seconds) to 0.63ml/second when the ICE stops at the end of S1b. As in the case of RPM curves, there are some oscillations (lower fuel flow only) of the curves before ICE stops. Notice that there is no any change at all in the curves for the transition from S1a to S1b warming stages.

    Next chart tells us precisely the moment of warming stages change and is the ignition timing chart. At 55 seconds there is change of all the curves from a delayed timing to a normal (advanced) timing. This transition announces the change from S1a to S1b warming stages.

    [​IMG]

    Click here for zoom in

    The transition from S1a to S1b is clearly shown at 55 seconds. For temperatures lower than 17ºC there is a linear shortcut during the first 55 seconds which is clearly identified in the 9ºC curve (dark line) that is linearly descendant from +5º (before DTC) at 0 seconds to -3.5º (after DTC) at 53.3 seconds.

    Ignition timing has a big importance in ICE efficiency. The instantaneous ICE efficiency chart is the following:

    [​IMG]

    Click here for zoom in

    During S1a stage the ICE efficiency starts at 10% and raises to 15%. The big step happens at 55 seconds when S1b starts and ICE efficiency jumps to around 27%. It is important to note that all curves are packed together so there is no visible influence of initial coolant temperature in ICE efficiency during warming-up.

    The energy generated by the ICE during warming stages when the car is stationary or moving very, very slowly (as are in all the cases recorded) goes to MG1 and there it generates electrical power. The hybrid battery current chart [positive=discharging ; negative=charging] is the following:

    [​IMG]

    Click here for zoom in

    During the first 55 seconds, the dark line (9ºC) is at the bottom of the set or curves. It marks the maximum of available current for charging the battery because the car was stationary in this particular warming-up. The oscillations (going up even to positive amps) are due to the steering (+0.5A when moving the steering wheel), "changing gears" which puts a short peek of +1.5A when selecting P, D or R; and releasing the brake pedal while in D or R which puts some 3A of discharging current. The idle discharging current is from 1.5A to 2.0A as it is shown on the flat right part of all the curves. The configuration at that time were always with lights on (LED headlights) NAVI & Radio ON but not heater nor AC/Defogging.

    The battery voltage depends on several parameters. One of them is the charging (or discharging) current. The currents drawn on previous chart have its impact on the battery voltage shown in following chart:

    [​IMG]

    Click here for zoom in

    The charging current step that happens at the transition from S1a to S1b which is from about 10A to 20A makes a 6 Volt (aprox) step in hybrid battery voltage.

    If we look at the ICE exhaust and catalyser temperatures, there are two probes; #1 probe is located before the catalyser and its temperature chart is the following:

    [​IMG]

    Click here for zoom in

    From my point of view there is nothing remarkable about #1 probe temperature.

    Let's see #2 probe which is located behind the catalyser. Its chart is:

    [​IMG]

    Click here for zoom in

    In the #2 probe temperature chart there is a common inflection point of all curves at 55 seconds, which indicates that the amount of heat coming from the exhaust is much less after 55 seconds (S1b) than before (S1a) This is the effect of the ignition timing change designed by Toyota.

    Let's see the charts of the electrical components temperatures. The hybrid battery temperature chart is not very exciting:

    [​IMG]

    Click here for zoom in

    Battery temperature seems to be about 2ºC warmer than initial coolant temperature.

    MG1 temperature chart has one step of 1ºC temperature raise in some curves:

    [​IMG]

    Click here for zoom in

    MG2 temperature chart is as exciting as the MG1 temperature chart:

    [​IMG]

    Click here for zoom in

    You may notice that MG1 is about one to three degrees centigrade warmer than MG2 in all curves. MG1 is close to battery temperature and MG2 is close to ambient temperature.

    Inverters temperature charts have some activity of heating and cooling. MG1 Inverter chart is:

    [​IMG]

    Click here for zoom in

    The behaviour of curves 9ºC and 12ºC is interesting because they are flat until S1b. Those are the only warmings in which the car was stationary with no steering nor changing gears. Probably it means that battery charging current pattern is defined for S1a; but if more current is needed from MG1 for steering, changing gears or slightly pushing the car with MG2, then the MG1 inverter comes into action and its temperature raises.

    MG2 inverter temperature chart is the following:

    [​IMG]

    Click here for zoom in

    This inverter has less activity than MG1 inverter, at least it is what its temperature tells us.

    The DCDC Inverter temperature chart is the following:

    [​IMG]

    Click here for zoom in

    This DCDC Inverter temperature chart looks like a mix of MG1 Inverter temperature and MG2 Inverter temperature charts. It has the same flat line during S1a for 9ºC and 12ºC curves that MG1 inverter chart has.

    The hybrid battery SoC chart looks like this:

    [​IMG]

    Click here for zoom in

    Well, not very much to say in this case. Initial SoC is not related with coolant temperature, and the only visible effect is that SoC stops climbing when ICE and charging current stops.


    Comparison with a conventional gasoline engine

    The ICE of our Prius uses the same strategy (retarded timing) as other conventional gasoline engines during the warm up. With this timing, the gasoline has no time enough to burn completely inside the cylinders and continues burning along the exhaust manifold, quickly warming the catalyser.

    In the following chart, you can see the timing of a conventional gasoline engine during the first two and a half minutes from cold (14ºC-29ºC) starts. This particular engine has two steps of retarded timing, while our Prius ICE has only one.

    [​IMG]

    Click here for zoom in

    The coolant temperature chart for this engine during these cold starts is:

    [​IMG]

    Click here for zoom in

    Yes! Difference with our Prius ICE is evident, coolant temperature climbs and climbs because the engine does not stop by itself.

    The RPM chart of this particular engine is not as clear as it was in our Prius. Some of the warmings were made with AC turned on, so these curves tend to go to 820RPM; the curves with no AC tend to go to 720RPM. Steering and changing gears (P-R-D) produce a lot of oscillations in RPM during these 2 minutes and a half. The RPM chart is:

    [​IMG]

    Click here for zoom in

    And now the gasoline flow chart for the first two and a half minutes of warming for this particular engine:

    [​IMG]

    Click here for zoom in

    Fuel consumption of this engine in the intermediate warming step is about the same as our Prius ICE, but after 68 seconds this engine has a gasoline flow between 0.35 and 0.60 militers/second while the ICE is running, which is a different picture compared with our Prius ICE that after S1b, the fuel consumption for warming or idling is zero.

    Big hugs from Frank


    PS: If you want to see a previous version of this post in Spanish, please go to here By the way, the link is correct. It seems the web page had some troubles when and1111 checked it. However the page was in Google cache here.
     
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  2. andi1111

    andi1111 Member

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    Hi!

    The link to the Spanish forum doesn't work.

    Thank you for the analysis and for sharing this very useful info.

    I vote for a sticky!
     
  3. Dark_matter_doesn't

    Dark_matter_doesn't Prius Tinkerer

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    Impressive data, thanks and keep posting.

    Are you planning to get a block heater? My experience is that it can get ICE temperature up to about 30 deg C at start-up after four hours of heater operation. It would be interesting to see the difference in your data, and whether there's significant savings in using a block heater year 'round.
     
  4. FrankTiger

    FrankTiger Member

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    Just to say that initial post of the thread is already finished.

    Ooopppsss. No totally finished. There are still to come a couple of future posts that will show the increase of transmission resistance with temperature and the influence of temperature in ICE efficiency. When those post arrive, I will complete the table of theoretical influence of lower ambient temperature in fuel economy.

    Big hugs from Frank
     
  5. FrankTiger

    FrankTiger Member

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    Thank you D_m_d

    It will be nice to get the data with a block heater, but I do not have an electrical plug near my car, so the only way is to estimate it. If ambient temperature (and initial coolant temperature with no heater) is 9ºC, you save 45ml of gasoline during warming-up in every start. For a 10mile trip is like going from 47.2mpg with no heater to 50mpg with the block heater.

    Big hugs from Frank
     
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  6. qbee42

    qbee42 My other car is a boat

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    Bob is back.

    Tom
     
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  7. andi1111

    andi1111 Member

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    How much is a few hours? 2 hours? 3 hours? The ambient temperature in our underground garage is 8°C right now. How long would it take to reach 30°C?
    How much wattage does the heater consume? Is there a 220V EU Schuko plug EBH available?

    Thank your for your reply!
     
  8. Dark_matter_doesn't

    Dark_matter_doesn't Prius Tinkerer

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    Last week, it was -3 C here, and the EBH got the engine temp to about 30 C after four hours (at night). I believe the Toyota EBH runs at 400 W. you should be able to get a 220 VAC version.
     
  9. FrankTiger

    FrankTiger Member

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    Hi Everyone

    First, thanks to all of you that gave this thread a 5 star rating.

    During this first week of February there is a Siberian cold wave across Europe that give me the opportunity to perform a warm-up in my Prius from 1ºC (34ºF) initial coolant temperature, which is much lower than the minimum temperature I had before in the charts (9ºC). So I post an update of the charts that have important data.

    The first graphic is the plot of the ICE running time and the gasoline burnt volume versus the initial coolant temperature.

    [​IMG]

    Click here for zoom in

    In the dark curve, which is read on the left vertical axis, you may see the ICE running seconds until the warming cycle (S1a&S1b) is done. On the pink curve (read on the right vertical axis) you may see the gasoline volume burnt by the ICE during those seconds. Now it seems that is better to have two linear parts for each curve and the equations are written near to the curves. The ICE running seconds for each ºC lower than 28ºC are from 4.6 to 5.3 and from 2.8 ml to 3.7ml of gasoline burnt.

    Following is the chart that represents ICE RPM versus time for every warming-up. The initial coolant temperature is marked on the relevant curve. Now the time axis goes up to three and a half minutes.

    [​IMG]

    Click here for zoom in

    The comment of the chart printed on the big arrow refers to the first chart where time and burnt gasoline is plotted versus initial coolant temperature.

    Next chart is the ignition timing chart. For initial coolant temperatures of 9ºC or higher, at 55 seconds there is change of all the curves from a delayed timing to a normal (advanced) timing, but for the 1ºC curve the transition happens at 63seconds. This transition announces the change from S1a to S1b warming stages.

    [​IMG]

    Click here for zoom in

    We already noticed the linear shortcut during the first 55 seconds which is clearly identified in the 9ºC curve (dark line) that is linearly descendant from +5º (before DTC) at 0 seconds to -3.5º (after DTC) at 53.3 seconds; and the new curve for 1ºC initial coolant temperature is much higher than the others.

    It seems that the ignition timing during S1a (and S1b too) is dependant of the actual coolant temperature. If we represent this new chart for all the warming, we get:

    [​IMG]

    Click here for zoom in

    Looking at the common path for all the curves, we can make the ignition timing map chart for S1a and S1b at 1300RPM, that depends of actual coolant temperature. The map chart is:

    [​IMG]

    Click here for zoom in

    The remaining charts show coherent results for the 1ºC initial coolant temperature warm-up. Anyway, if someone is interested, let me know and I will post the updated charts.

    Big hugs from Frank

    PS. I am still working on the promised posts: variation of transmission and tires friction with ambient temperature; and ICE efficiency with temperature. When those are finished, I will update the table of the initial post of this thread
     
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  10. Sergio-PL

    Sergio-PL Member

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    You did great job updating those charts. As for siberian cold in Europe - lowest temperature I was driving Prius was -18 by night and -15 deg C during start-up. (parking on the road so battery and coolant in the same temp after 15 hours of parktime).

    As I had to drive it right from the start, not waiting for heatup I have few observations on driving with frozen car and frozen battery that others may be able to verify during normal use.

    - engine starts immediately after READY
    - car refuses to use battery power during S1a (more on that below)
    - changing from P to D / R changes sound of the engine (like in transition from S1a to S1b)
    - even slightest touch of accelerator immediately increases engine RPM (also during reverse)
    - engine RPM rises while accelerating on the left half of HSD zone
    - 60 - 70 seconds after ICE startup slight touch of accelerator changes engine sound but RPM stays more or less on the same level (sounds like change from delayed to advanced timing and back to delayed). This effect disappears as soon as car interior (and probably HV battery) heats up a bit
    - while in P engine load varies and car moves forward / backward within a locked wheels range - strange feeling
    - during driving for first 4 - 5 minutes engine RPM are much higher in ICE/Hybrid range than during normal (heated) driving even with 7 bars on battery during start up.
    - regen sound and feeling while braking from 30 kmh (CHG bar ~ 90% full) seems to be the same as within higher temperatures

    I don't have SG but it looks like Prius don't like to use frozen battery - let it heat up before use. Another interesting thing is that battery is not charged to high when cold. Normally, starting it at 0 degrees C SoC goes up from 4 to 7 bars within first 3 minutes. When frozen - SoC level stays within 1 bar range from start-up level, even with engine running higher RPM,

    I almost don't use rear/mirrors defrosters - no need for that so it's not consuming additional power.

    Fuel consumption read from car on 7.5 km trip and winter tyres is:
    - 5.3 l/100km Tamb >= 5 deg C
    - 5.9 l/100km Tamb >= -3 deg C
    - 8.5 l/100km Tamb <= -12 deg C
     
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  11. Braddles.au

    Braddles.au DEFAnitely using an EBH

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    DEFA in Norway make a modular Engine Block Heater, Cabin Heater and Battery Charger system that is 230 volts and with a Schuko plug.
    DEFA / Find your engine heater
    I just bought one.

    UPDATE 14/07/2012: Mine just arrived from Germany from CARandCAMP.de . Strictly speaking the plug is a CEE 7/7 plug so it should work in a Schuko socket.
    The part numbers were:
    413840 DEFA SafeStart 3840 for Prius 1.8 2ZR-FXE (NVW30)
    460787 (460915 + 460921) DEFA SafeStart Connection Set 5 metres
     
  12. Maxwell61

    Maxwell61 Active Member

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    So folk, a simple spoofing with a resistor (ON/OFF) on the wire of the HV temp sensor should give us the opportunity to skip the 2 major inefficiencies of S1a?

    That is, avoid to drive on HV during S1a and to make ICE to jump at the least at the 27% efficiency typical of an S1b, pushing from the very first moment?

    And, in a word, have the possibility to exclude any ICE-induced recharge of the battery if we like?

    Moreover, using a mode already optimized by Toyota?

    WOW
     
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  13. edwardob

    edwardob Member

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    i like mods.......how would this be done?
    i would'nt know where to start......but i'm not afraid to try!
     
  14. Maxwell61

    Maxwell61 Active Member

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    I hope the Priuschat modders will step in :)

    In the meantime, in our italian forum, we are working hard already about it: wires identified and the resistor of one of the wires is already in a fridge to measure the variation of the resistance to calculate the resistor to apply to the wire itself.

    The 3 sensor's wires for the Prius III and the unit were a CAN signal to the ECU starts, are clearly visible in the 2 pics, bearing in mind that just one temp sensor hack should trigger the "Freeze mode":

    [​IMG]

    [​IMG]

    As a side note, an our finnish member just confirmed us the behaviour reported at -15°C few msgs above.
    I'm waiting the confirmation that, if the battery can be recharged by regen in this mode, it's likely can give the usual very light assistance in acceleration, and then, that we can consider the "Freeze mode" as an S1b.

    I'm wild guessing that a similar simple condition is triggered in Ford Fusion Hybrid to go directly in S1b shifting in "L", bypassing S1a.
     
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  15. edwardob

    edwardob Member

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    anyone any idea what resistor could be used......I willing to try....
     
  16. Maxwell61

    Maxwell61 Active Member

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    Hi Edwardob, just to avoid any further OT i'll reply in a new thread!
     
  17. edwardob

    edwardob Member

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    Thanks.....but. .not familiar expression OT?
     
  18. Maxwell61

    Maxwell61 Active Member

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