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OVMS Module and Cooldown

Discussion in 'Roadster' started by simonog, Apr 6, 2015.

  1. simonog

    simonog Member

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    Can user of the OVMS module help me with some context please? I have read the notes on how the module performs a cooldown.

    If the car does a perfectly normal charge without using the module in any way, does it trigger a cooldown whenever it determines the battery is too warm?

    If so, will an OVMS triggered charge without any mention of cooldown simply do a cooldown when it needs to?

    If so, why would one use OVMS to force a cooldown as part of a charge operation at a location and not just let the car make its own mind up when to cooldown?
     
  2. Curt

    Curt Roadster Signature #55

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    Yes, cooling will kick in as needed during regular charging.

    Cooldown is something specific to Tesla Tattler and OVMS. The idea is to force cooling of the battery with minimal charging. Many of us use this heavily in the Summer (I haven't had a cool down cycle so far this year).

    The most common use is to initiate Cooldown, if needed, to bring the battery temperature down immediately on plugging in, then the Roadster can sleep until the scheduled charging time. This ensures that the battery is not left sitting around hot, and the cooling pump can shut down, rather than running for hours on end.
     
  3. simonog

    simonog Member

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    Doesn't it require the cooling pump to run to cool the battery? In which case how does a cooldown differ from what would be going on naturally? (I am assuming that in your scenario on a really hot day you have driven the car quite hard thus heating the battery more.)
     
  4. supersnoop

    supersnoop Tesla Roadster #334

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    It's a little more complicated than that. A standard charge will keep the battery cool, but not as cool as a cooldown cycle. The difference between Range and Standard charging is that, during Range charging, the car cools down the battery first so is can fill to capacity. Any time the battery gets too hot from charging, the car cools it down again. This is the technique exploited to perform a cooldown. In a Standard charge, the battery may be cooled, but not as aggressively as during a Range charge.

    As noted by Curt, it's not a good idea to leave a car sit with a hot battery. Even if you plug in when you get home, if you don't initiate a charge, the car will not cool down, at least not as much as it should.

    Personally, I've seen my battery recover lost range, and improve it's health by enabling the cooldown feature.
     
  5. simonog

    simonog Member

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    Really helpful explanation. Thank you. I shall implement a cool down set of commands on plugin!

    With OVMS, is it possible to have cool down on plugin and to set a later start time for the proper charge? If I do
    ACC PARAMS COOLDOWN CHARGEAT 2330 say, won't it delay COOLDOWN until 2330 and then mess up the intended charge as COOLDOWN will be trying to run at 13A and the charge at the site capacity?
     
  6. dsm363

    dsm363 Roadster + Sig Model S

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    To enable cool down do I just put a '1' in the field 15 under Parameters?
     
  7. simonog

    simonog Member

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    This experience is most helpful - thank you.

    If I set COOLDOWN at a location and a scheduled charge kicks in from the car while COOLDOWN is going on, can the car cope with this? I recently had an example of the car cycling between 13A and 70A every few seconds which made me think it could be getting confused. I disconnected he OVMS module to allow the 70A charge to run without sounds of conflict from the plumbing.
     
  8. markwj

    markwj Moderator, Asia Pacific

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    One comment: In hot climates, the roadster built-in cooling logic may not cool the battery sufficiently below the 31C threshold to stop the coolant pump running 24x7 resulting in the car being unable to sleep. I personally use cooldown in the summers here to bring the battery temperature down sufficiently.

    - - - Updated - - -

    Yes. The cooldown will happen on plugin. The charge itself can be scheduled for later (often TOU times) with CHARGEAT or CHARGEBY.
     
  9. Botbldr45

    Botbldr45 Member

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    To turn on the COOLDOWN option in OVMS you just set Parameter #15 to "1"?
    If so, then the cycle will automatically start at plug in if battery temp is above 27C(about 80F)
    If this is correct, can you set a lower limit where you want the COOLDOWN cycle to stop...... say at 10C ( 50F)??

    If possible what are the commands or is there a list of commands that address this in another post?
    Thank You
     
  10. markwj

    markwj Moderator, Asia Pacific

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    Feature #15 is CAN_WRITE. Setting that allows the module to write to the CAN bus. It allows the module to send commands to the car - to start/stop charge, change charge limit, lock/unlock, etc.

    Parameter #15 controls the cooldown limits. The default (if empty) is 31:60 - that is a limit of 31celcius and 60minutes. You can adjust appropriately.

    To initiate a cooldown now, you need to sms COOLDOWN. Either that, or use the ACC feature with the COOLDOWN parameter.

    See here: https://github.com/openvehicles/Open-Vehicle-Monitoring-System/raw/master/docs/OVMS_UserGuide_TeslaRoadster.pdf
    for a list of available commands.
     
  11. Botbldr45

    Botbldr45 Member

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    @ markwj
    Thank you very much
     
  12. Botbldr45

    Botbldr45 Member

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    @mark
    Ok now it is getting hot in Maryland and cooldowm is needed. My temp readings are in F, so I need to go to Perameters #15 and type 70:60 to get the cooldown feature to try to cool battery to 70F in a 60 min period of time..........is that correct?
     
  13. Curt

    Curt Roadster Signature #55

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    Nope - It doesn't matter what units you have set to display temperatures, the Parameter is still Celsius.

    I use 30:60, which is enough to make the car sleep and stop running the coolant pump. To reach 70F, you would use 21:60.

    BTW - that doesn't get you to 21C in 60 minutes, it stops when you reach either 21C or 60 minutes. If you haven't reached your target temperature, you can issue another COOLDOWN command via SMS.
     
  14. n2mb_racing

    n2mb_racing Member

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    Can you do a cool down when not charging?

    And the full command to set it to automatically perform a cool down when I get home is:

    ACC HERE
    ACC PARAMS COOLDOWN
    ACC HOMELINK 1 (if I also want it to open my garage door at this location)
    ACC ENABLE 1

    Or something like that?
     
  15. dsm363

    dsm363 Roadster + Sig Model S

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    So when do you do the cool down? When you come home with a warm pack and want to cool it down but don't want to charge? Thanks.
     
  16. n2mb_racing

    n2mb_racing Member

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    I think normally before charging. I wanted to know if it can be done when it isn't plugged in at all.

     
  17. markwj

    markwj Moderator, Asia Pacific

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    You want to cool down as soon as you get home.

    Whether you do a charge immediately after cooldown or not depends on your electricity situation. People on TOU plans tend to delay the full charge until later in the night.
     
  18. simonog

    simonog Member

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    The way COOLDOWN is implemented is by certain kinds of low current charging. You therefore need to be plugged in to the mains (power).
     
  19. Botbldr45

    Botbldr45 Member

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    Ok so I tried those commands by sms on iPhone
    Went to OVMS app and checked parameters to see this

    image.jpg

    And Cooldown doesn't work.., any ideas

    - - - Updated - - -

    image.jpg image.jpg

    These are the SMS messages

    - - - Updated - - -

    My son told me the world was made up of Protons, Neutrons, Electrons and Morons.
    Guess which one I feel like:crying:
     
  20. Roadrunner13

    Roadrunner13 Member

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    One thing your parameters screen shows is a bug I've also witnessed.
    Parameter 15 is not set to the proper default of '31:60', it's filled with rubbish.
    As Markwj mentions earlier in the thread, parameter 15 must be set to something similar to '31:60', so erase the rubbish and replace it with that string.
    I'm pretty sure that's a minimum for cooldown to have a chance to work.
     

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