HV battery Oil pan pre-heating in winter

Discussion in 'Gen 3 Prius Main Forum' started by Abarnabe, Feb 16, 2025.

  1. vvillovv

    vvillovv Senior Member

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    agreed,good experiment ! but the temp of what? and what was ambient temp and how long did it take to return from 30 to 9 C? just me being curious and hoping it doesn't kill my cat ... ;)
     
  2. Abarnabe

    Abarnabe Member

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    it was the coolant temperature, the ambient temp was 9°, I'm not sure about how long it took to go back to 9°, but I went for a 45 minutes drive reached 87 degrees, parked the car and went for 30 minutes walk, at my return the car started directly in S4, the coolant temp was about 50° , the ambient emperature was still 9°
     
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  3. Abarnabe

    Abarnabe Member

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    yes, the original toyota heater should go into 120 vac, but I installed a generic heater rated 240v 350w, it absorbs about 1.6 amp an hour, as per Max 2, the usable battery power is 2.6 amp out of the 6.5, so not enough, I' ll plug it in to the wall outlet from now on, and the insulation helps to hold the heat between multiple trips on the same day, so you can start directly in S4 or S3
     
  4. rjparker

    rjparker Tu Humilde Sirviente

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    That is pretty much normal for us in South Texas in winter; 48f (9c) ambient, warming up to 188f (87c) after a drive of more than ten minutes and dropping to 122f (50c) after a 30 minute off time.
     
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  5. Abarnabe

    Abarnabe Member

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    after 2 hours with block heater on the temp goes from 9 to 45, If I turn IG on ready the temp drops to 35C immediately , could the thermostat on it's way out? I have 297000 km and it's never been changed in 15 years
     
  6. Abarnabe

    Abarnabe Member

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    ok, the insulation is applied only on the oil carter, not the cylinder walls , I hoped it had a positive effect on the coolant too, but this is not the case apparently, I'll try to add some insulation on the cylinders or a blanket on top of the engine
     
    #46 Abarnabe, Mar 13, 2025
    Last edited: Mar 13, 2025
  7. vvillovv

    vvillovv Senior Member

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    I did a similar experiment with 120 volt AC ceramic heater in the cabin during winter months, to hopefully warm the hybrid battery. The cabin got really warm, like a mild summer day, but when dr prius started supporting the Prime I found out that none of that heat reached the battery pack. And that warm like a summer day cabin temp faded quickly without the cars heater being used. In 0 degrees F ambient temps and no heater running, I could feel every draft that making it's way though the firewall and it took about 5 miles at 35 mph for all that summer heat feeling to be replaced by normal winter temps. And running the ceramic heater even at 900 watts used as much electricity as the car used to charge the battery pack.
    Now I know why Toyota but a 300 watt heater under the Primes Hybrid Battery and only uses it when temps drop below freezing and only for a day to keep the pack in the 40s F and one (maybe two) more days, but the hybrid battery temps drop into the 30s F on the second day, if the car was not used for two days in a row.

    I wish you the best at figuring out the best way to keep your engine compartment warmer during the winter. ;)
     
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  8. Abarnabe

    Abarnabe Member

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    I wrapped timing chain carter, top of the head and front cylinders wall, maybe a bit overkill, I was in a freeway congestion and the coolant rose to 95c, so I turned blower and heater to the maximum to lower the temp back to 90c
    upload_2025-3-19_21-53-35.jpeg


    upload_2025-3-19_21-48-51.jpeg
    upload_2025-3-19_21-47-33.jpeg
     

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    #48 Abarnabe, Mar 19, 2025
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  9. rjparker

    rjparker Tu Humilde Sirviente

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    Overkill may be kind....

    Now you can concentrate on the inverter coolant temperature which has a much lower alarm limit of 65c (149f) that can trip in high ambient traffic.
     
  10. Abarnabe

    Abarnabe Member

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    3.5 l /100 km or 67.2 mpg on the last 1200 km / 745 miles , I know there is a 7% error, but usually I see these figures in summer, not in March.
    I think insulation and block heater definitely help and quite a bit.
    I removed the whole upper grill block for the inverter, but fully blocked the lower one.
     

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    #50 Abarnabe, Mar 23, 2025
    Last edited: Mar 23, 2025
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  11. Abarnabe

    Abarnabe Member

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    To conserve additional heat ,especially when the car is parked, I close 2 gaps on the top part of the engine bay that have been missed in the grill block strategy.

    The gaps are 10 cm wide and 5 deep.
    I used the usual pipe insulation.
     

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  12. Mendel Leisk

    Mendel Leisk Senior Member

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    I do that one, leave it in year 'round. Seems ok.
     

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  13. Abarnabe

    Abarnabe Member

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    Yes, I copied your insulation along the fenders and it seems effective.
    I felt heat escaping from the gap marked in red both on right and left side, I filled it with the same material, this morning I reaced 55°c after 60 minutes of block heater, and I never reached it before.
    The gap is 10 cm wide and maybe 5 cm deep .
    upload_2025-4-2_18-56-37.jpeg
     

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    #53 Abarnabe, Apr 2, 2025
    Last edited: Apr 2, 2025
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  14. Abarnabe

    Abarnabe Member

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    I inserted an insulation pipe in another one to increase the thickness

    upload_2025-4-13_16-52-18.jpeg

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