Is cabin heat "free" if a Prime is in HV mode?

Discussion in 'Gen 5 Prius Main Forum' started by Will B, Mar 24, 2026 at 11:41 PM.

  1. Gokhan

    Gokhan Senior Member

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    In the Gen 4 PHEV in HEV mode, you can turn off the heat pump by using the A/C button and keep only the fan running, which will utilize the engine-coolant heater core to warm the cabin. In fact, even with the fan off, you can still feel heat coming from the vents.

    I don’t see why this should be impossible in the Gen 5 PHEV, but then they added refrigerant battery cooling, which could lead many Gen 5 PHEVs to the junkyard once the battery warranty expires, since repairs would be very costly. The Gen 6 RAV4 PHEV already uses engine coolant to cool the battery, so this refrigerant cooling system will remain unique to the Gen 5 Prius PHEV.
     
    #21 Gokhan, Mar 26, 2026 at 3:07 AM
    Last edited: Mar 26, 2026 at 3:14 AM
  2. Trollbait

    Trollbait It's a D&D thing

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    The current Rav4 plug ins also use refrigerant cooling. Other Toyota EVs might also use it, or use the AC to chill the blown air.
     
  3. Gokhan

    Gokhan Senior Member

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    You mean the outgoing RAV4 PHEV. Well, Toyota is done with it. It will never use it again. When there is a leak, and it leaks easily, it costs $20,000 to fix it.

    In my Gen 4 Prius Prime PHEV, the A/C didn’t even turn on once to cool the cabin for the battery.
     
  4. Hammersmith

    Hammersmith Senior Member

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    The outgoing RAV4 PHEVs used refrigerant cooling for the HV batt, but the new gen RAV4 PHEV uses water cooling. (RAV4 HEV uses air cooling like always.) The Prius PHEV continues to use refrigerant cooling. It looks like the current BEVs(bZ/RZ) use water cooling. I don't know what the new BEVs(C-HR/Highlander/ES) are going to use, but I'm guessing water.
     
  5. hill

    hill High Fiber Member

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    Don't most EVSls simply use coolant loops? And wouldn't a refrigerant loop be more expensive? If so it's hard to follow the logic.
     
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  6. BiomedO1

    BiomedO1 Senior Member

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    the gen1 nissan leaf used air cooling. that's why their range went down quickly after a few years - batteries overheating.
     
  7. hill

    hill High Fiber Member

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    Irony the very most loyal EV Enthusiasts were completely soured by Nissan's complete failure - to the point where they had to file
    suit - because Nissan 'said' the Gen 1 was good for a ~100 miles when you're lucky to get 75 Mi under great conditions at freeway speed - only to find out a couple years later your battery had lost Maybe 20% plus of its capacity. What a Fiasco that was.
     
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  8. Trollbait

    Trollbait It's a D&D thing

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    It costs so much to fix because Toyota didn't allow for leak repair in the design, so the entire battery would need to be replaced.

    Since they didn't want to design for use of a readily available aqueous coolant, the bZ4X uses a dielectric coolant that costs more to replace for regular maintenance.

    And you live in a mild climate, so why mention this? Leaf owners in California weren't seeing the degradation seen by those in Arizona.

    Part of the reason the gen4 PHEV pack took up so much space is because bigger channels for moving air through the battery than if a liquid is used.

    Refrigerant means narrower pipes. Makes it easier to route them. These first showed up in hybrids. I think going back to the OG Insight.

    Then the coolant loops available in the car might be too warm for a battery. Plumbing could also be a factor with the different components being cooled by the system. The Mach-E has a mess of connectors and tubes. Tesla developed the octovalve.
     
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  9. BiomedO1

    BiomedO1 Senior Member

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    I did like the little turtle that popped up in the gauge cluster when it went into limp mode; low battery.:rolleyes::LOL::ROFLMAO::whistle::cool::p:D
     
  10. hill

    hill High Fiber Member

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    sounds like someone's never lived in Imperial County, Inyo County (home of world famous Furnace Creek's hot temps) Riverside County, or San Bernardino County California.

    but yea - both States had record number of battery failures. Coastal state of Washington? Their traction packs lasted longer than most others
     
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