Arduino Automatic Coolant Temp Hack for Better MPG's

Discussion in 'Gen 2 Prius Accessories & Modifications' started by TheForce, Feb 23, 2011.

Page 5 of 5
  1. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    11,356
    3,604
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I have not tried this project, but lately I have been downsizing my Arduino projects, putting the Arduino code into a smaller LilyTiny (ATTiny) chip for smallness. Not everything can be done this way of course.
     
    #81 wjtracy, May 29, 2015
    Meg&Bear likes this.
  2. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    As small as the code is and as simple as the circuit is I would think the ATTiny would work well as a finished device. I have not looked into it though. I have plenty of Arduino micro's laying around so I dont really need anything else.
     
    #82 TheForce, May 29, 2015
  3. mindogas

    mindogas Junior Member

    Joined:
    Nov 7, 2014
    12
    8
    0
    Location:
    Kaunas
    Vehicle:
    2007 Prius
    Model:
    Two
    Could you detail this problem more? Did arduino read bad temperature from analog input or digital pot didn't holded desired temperature throw transistor? This happen then ambient temperature was hot? I'm asking because eventually i will face same situation sooner or later becouse setup is the same.

    Already finished prototype of my standalone arduino:
    DSC_0784.JPG
    Done simulation and seams all things are OK:
    DSC_0780.JPG
    Tomorrow I'm going to try it in car. For longer term testing this form of device will be safer and more reliable solution. We all know whats happens with losing jump wires and accidents during hard breaking.
     
    #83 mindogas, May 29, 2015
    Meg&Bear likes this.
  4. mrbigh

    mrbigh Prius Absolutum Dominium

    Joined:
    Sep 6, 2005
    3,686
    699
    2
    Location:
    Long Island, NY
    Vehicle:
    Other Electric Vehicle
    It is nice having this thread resurrected and with positive results
     
    #84 mrbigh, May 29, 2015
    Meg&Bear likes this.
  5. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    The transistor is temperature sensitive and you will most likely see a difference in readings during the summer with a 100F+ degree car and in the winter when its below freezing. This may result in the fake temperature being below the 157F point needed or close to or above 190F and I think if the temp gets above 200F the fans kick on. I never got around to see what the exact range is. Just let your car set out in the sun for a few hours and see what the result is. I don't remember if the fake temp gets hotter or colder during the summer/winter. Use canned air up side down to spray the transistor to get a good idea on how temperature changes the results.
     
    #85 TheForce, May 29, 2015
    Meg&Bear likes this.
  6. mindogas

    mindogas Junior Member

    Joined:
    Nov 7, 2014
    12
    8
    0
    Location:
    Kaunas
    Vehicle:
    2007 Prius
    Model:
    Two
    Attiny or smaller package Atmega's could be used. But if I look more to Automotive family of AVR's. Thous have better temperature range, stable performance and the most of all buil-in voltage protection for short-circuit monitoring.
     
    #86 mindogas, May 29, 2015
    Meg&Bear likes this.
  7. mindogas

    mindogas Junior Member

    Joined:
    Nov 7, 2014
    12
    8
    0
    Location:
    Kaunas
    Vehicle:
    2007 Prius
    Model:
    Two
    After two days and about 10 trips i must say things are stable. The only question for me is calibration quality. In original design The Force uses +12 power line and internal arduino VREG. In this case voltage reference on car vas a little bit different then arduino's +5V, so calibrations should be different if i'm using +5V for Atmega power from ECU. The force, could you explane what temperatures there you targeted as setpoint? I will check if i'm getting same results or not.
     
    #87 mindogas, May 31, 2015
    Meg&Bear likes this.
  8. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    I really dont remember. I think my target was between 160-175F. As long as your not above 190F and not below 160F you should be fine because below 157F you wont get into full hybrid mode and above 200F you kick on fans and throw codes. What I was doing was forcing the engine to run to heat it up and turning on and off the ACTH to see what values it got vs the actual temp from the car. As long as you stop faking the temp when the actual temp gets to around 180F you should be Ok and not damage the car. You kind of have to play with it and see what values works best.
     
    #88 TheForce, May 31, 2015
    Meg&Bear likes this.
  9. mindogas

    mindogas Junior Member

    Joined:
    Nov 7, 2014
    12
    8
    0
    Location:
    Kaunas
    Vehicle:
    2007 Prius
    Model:
    Two
    So now my temperatures are facing 175F (or 79-80C) so it's OK. Also faking starts from about 112F (44-45C) and i'm OK with that too.

    I'm interested about other thing. If i look to arduino serial out during faking temperature near cold point i see high digital pot value:
    RTA;=;294;ADC;=;102;Average;=;101;DP;value;=;233

    If transistor are not so good on passing voltage on hot environment it will be problem because to compensate pot will go to the max 255 value. I will test this thing then i'll have laptop in may car during hot day.
     
    #89 mindogas, May 31, 2015
  10. ccdisce

    ccdisce Active Member

    Joined:
    Oct 10, 2010
    259
    187
    0
    Location:
    Stone Mtn GA USA
    Vehicle:
    2008 Prius
    Model:
    N/A
    Vbe will vary with temperature to the tune of 26mV/C.
    You may want to consider using a LV Rail-to-Rail OPAmp in a voltage follower mode as a buffer and remember to match the + and - input impedances for optimum thermal stability.
     
    #90 ccdisce, Jun 8, 2015
    SFO likes this.
  11. Radu Stauceanu

    Radu Stauceanu Junior Member

    Joined:
    Sep 19, 2016
    10
    4
    0
    Location:
    Romania
    Vehicle:
    2006 Prius
    Model:
    II
    anybody have a good working version of this, i would like to build it. can I use MCP40D18T-502ET Dig. Potentiometer 7bit 5k ?
     
    #91 Radu Stauceanu, Sep 8, 2017
  12. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    Is there a reason you need to use the 7bit over an 8bit? More steps gives you more control over the target temp. You could put a few of them together to get a higher resolution though.

    I never finished this project. I ended up getting one of ccdisce's versions. It has worked great but I have had issues with it not working all the time the past few years. I never tried to diagnose the issue with it either. I've had too many things break over the years ( some car related ) and not enough time to work on any projects.
     
    #92 TheForce, Sep 8, 2017
    Meg&Bear likes this.
  13. Radu Stauceanu

    Radu Stauceanu Junior Member

    Joined:
    Sep 19, 2016
    10
    4
    0
    Location:
    Romania
    Vehicle:
    2006 Prius
    Model:
    II
    Ok, I found some 8 bit ones.
    Did you have a problem with the car because of the mod?
     
    #93 Radu Stauceanu, Sep 11, 2017
  14. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    No issues with the mod. I just have bad luck.

    Car related issues I've had...
    1. My Hymotion battery will only give about half a charge sometimes. Dont know why and live too far away to have it looked at.
    2. My in car PC bit the dust. Sucks having to listen to the same thing on radio every day.
    3. My MFD stopped working about 5 months ago but I can still drive the car.
    I think there is a few minor things I'm forgetting but those are the major 3. Dont have the money to fix those because of other things breaking around the house.

    Good luck getting this working and let me know how it goes.
     
    #94 TheForce, Sep 11, 2017
    Meg&Bear and SFO like this.
  15. ericbecky

    ericbecky Hybrid Battery Hero

    Joined:
    Mar 12, 2004
    4,379
    3,238
    1
    Location:
    Madison, Wisconsin
    Vehicle:
    2005 Prius
    Model:
    Two
    Thanks for the update The Force.

    Sidenote.. I'll likely be removing (another) dead Hymotion system next week.
    Very few of these remain working anymore.

    If you are ever up this way, give me a ring.
     
    #95 ericbecky, Sep 11, 2017
    SFO likes this.
  16. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    I doubt I will ever travel that far by car again but if I do I will let you know. Thanks.
     
    #96 TheForce, Sep 11, 2017
    Meg&Bear and SFO like this.
(You must log in or sign up to post here.)
Page 5 of 5