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EV Mode ... is it temperature sensitive?

Discussion in 'Gen 2 Prius Accessories & Modifications' started by ralue, May 6, 2010.

  1. ralue

    ralue New Member

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    I recently installed the EV Mod, DIY style (Radio Shack button w/ wiring to #27). It worked great, with no problems and within the given parameters: <33mph, no hard/aggressive acceleration, sufficient SOC.

    However, the past couple days the EV Mode has not been engaging on my afternoon and evening drives... it is working fine in the morning/early hour drives.

    Since the temperature has climbed to the upper 80's and low 90's these same past couple days, I'm wondering if EV Mode has a temperature limit? It doesn't seem logical but I could rationalize such a limit.

    Any thoughts?

    Thanks!
     
    #1 ralue, May 6, 2010
    NortTexSalv04Prius likes this.
  2. TheForce

    TheForce Stop War! Lets Rave! Make Love!

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    Yes. If the battery is too hot or too cold you wont be able to get into EV mode. With outside temps in the 90s the inside temp would be much higher causing the battery to get too hot. Running the AC for a while will cool it down enough to use EV again.
     
    #2 TheForce, May 6, 2010
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  3. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    Force is correct. I often roll the back right window down to try and get more air into the battery vent when the temp's really hot.
     
    #3 TonyPSchaefer, May 6, 2010
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  4. ralue

    ralue New Member

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    Thanks, guys!

    Are there any other mods/methods to cool the battery? I live in Texas so this is going to be somewhat of a challenge for the next 4-5 months...
     
    #4 ralue, May 6, 2010
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  5. JimboK

    JimboK One owner, low mileage

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    Actually, cooling the battery after it bakes in the summer sun is akin to closing the hen house door after the fox gets in. The battery is a large thermal mass and takes time to cool. Meanwhile, you've lost the best opportunity for EV mode -- during ICE warmup. Then, if your goal is maximal fuel economy, you may be running the AC when you otherwise might choose not to, which may further heat the battery by drawing current from it. Making matters even worse, there are other behaviors that hurt fuel economy with a hot battery.

    I recommend taking whatever steps necessary to prevent it from getting so hot in the first place. What I do:

    • Park in the shade whenever possible.
    • Keep windows cracked. I have WeatherTech deflectors to avoid the undesirable effects of a sudden shower.
    • Have tinted windows.
    • Use a windshield sunshade.
     
    #5 JimboK, May 7, 2010
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  6. ralue

    ralue New Member

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    Jim - thanks for the tips... my questions was exactly your point: not to be reactive but proactive (i.e. how to keep the battery at a lower temperature by generating a higher volume of consistent air flow during the summer months).

    I will do better about parking in the shade and generally keep the windows cracked (except in threat of rain), have tinted windows (5% on the 4 small windows, windshield strip and 2 back hatch windows; 35% on door windows) and I use a windshield sunshade.

    I'm going to investigate the system so I can see and understand it better... maybe I'll think of something. I hate being restricted from EV Mode so often - today it wouldn't go to EV Mode and it wasn't even 80F.
     
    #6 ralue, May 8, 2010
  7. njeanneb

    njeanneb New Member

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    Which battery gets overheated? The OEM battery or the Enginer battery? How does keeping windows cracked keep the OEM battery cool?

    Aso, Jimbo, I went to the weathertech website, and they didn't have deflectors for our 2007 Prius! :-( Any other suggestions?

    Jeanne
     
    #7 njeanneb, May 20, 2011
  8. Flaninacupboard

    Flaninacupboard Senior Member

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    The OEM battery getting warm is what locks you out of EV. i think in an Enginer install where the whole kit gets warm it probably makes things worse for the OEM battery, since once parked/switched off that heat is just going to spread to the surrounding area.
     
    #8 Flaninacupboard, May 20, 2011
  9. SFGiant-and-Plugin-Fan

    SFGiant-and-Plugin-Fan New Member

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    I and others with Enginer kits have installed this mod with much success. I agree with the poster that said avoid hot places/situations, etc, but that is not always possible. This mod is the fastest way to cool your OEM battery and keep it cool.

    Prius OEM fan control - EAA-PHEV

    Jeff
     
    #9 SFGiant-and-Plugin-Fan, May 27, 2011
  10. NortTexSalv04Prius

    NortTexSalv04Prius Active Member

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    Anymore tips
    If your in Texas,Arizona,New Mex , and some other southerly state the summer can be harsh with several months at 99plus or triple digit temps. Also shade is hard to come by with no trees or coverin.
     
    #10 NortTexSalv04Prius, May 10, 2012
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