Battery Cooling System

Discussion in 'Honda Hybrids' started by roncad, Apr 20, 2009.

  1. roncad

    roncad Member

    Hi,

    In regards to a HCHII:

    Does anyone know the specs for the battery cooling system. Specifically the temperature that the fan kicks in? Is the IPU trying to maintain a certain temperature or a range? Does the fan come on as needed or is it always blowing?
     
  2. Chuck

    Chuck just the messenger

    Welcome to CleanMPG!

    This might give you an idea: the temp probe on the 2000-2006 Insights activate the fan at 120F
     
  3. roncad

    roncad Member

    Thanks. I have been looking online to see if the HCHII is the same. It has a completely different IPU from what I can tell but this helps a bit.
     
  4. msantos

    msantos Eco Accelerometrist

    Hi roncad;

    On the HCH-II the IPU fan is throttled and as a critical active component it too, is monitored in case it fails. I have published the temperature thresholds that govern the IPU cooling before but I do not recall the exact values. I'll look those up again, but from my vague memory the thresholds are not driven by the battery pack sensor temperatures alone. In fact, depending on the circumstances you may find other IPU modules being the greatest and most urgent source of heat (DC-DC, AC Driver and MCM).

    Cheers;

    MSantos
     
  5. Chuck

    Chuck just the messenger

    Forgot to mention not only does the battery pack heat up, but the MCM (Motor Control Module) does too. The MCM is basically the transformer sending the power to the electric motor under the hood and often is the hottest component in the battery pack area.
     
  6. roncad

    roncad Member

    Thanks MSantos,

    Is it possible then that at times the fan may not need to be on at all?
     
  7. Chuck

    Chuck just the messenger

  8. msantos

    msantos Eco Accelerometrist

    If memory serves me right, I believe it always runs. This is because they have found the fan to "stick" under some scenarios - especially if it was started with a low throttle signal - and that was definitely not good as a condition of overheat would be created slowly, but surely. So, the approach appears to be a full spin start followed by a low rpm signal to guarantee that it is always running and able to ramp up in speed as required.

    To be sure, I'll look into it again as soon as I get a chance.

    Cheers;

    MSantos
     
  9. roncad

    roncad Member

    If it is supposed to always be on, then mine must not be working. I do remember hearing it buzzing gently last summer on warmer days but I listened for it yesterday and noted zero sound coming from the duct over the back seat. I had assumed it only comes on when it needed to but now I am worried that it is not working.

    Wouldn't the car throw an IMA or battery light if the fan was not working? Or is it so dead silent when it is on "low" that even pressing your ear up against the vent results in no sound?
     
    Last edited: Apr 20, 2009
  10. msantos

    msantos Eco Accelerometrist

    roncad, as I tried to indicate I am going on my memory alone and I would not want you to get alarmed needlessly just in case I am missing a detail or two.

    Besides, I would let the weather get a little warmer and see if the fan spins fast enough for you to notice an indication of forced air flow. Please remember that the whole IPU enclosure also provides a great deal of passive cooling too and only in the warmest of days under very intense city driving with some AC use would you notice the fan at full throttle anyway.

    Cheers;

    MSantos
     
  11. roncad

    roncad Member

    Thanks again MSantos.

    I understand that you are going by memory and I thank you for your info. I have one last question that you may be able to answer.

    Do you know if the IMA light is supposed to come on in the event of fan failure? Perhaps throw an error code. Seeing this seems to be an important part of the cooling process, I would have thought Honda would have ensured to "let us know" should something so critical fail. Again I appreciate your feedback.
     
    Last edited: Apr 21, 2009
  12. msantos

    msantos Eco Accelerometrist

    Oh yes, don't you worry about that. The IMA light will come up for sure. ;)

    There will definitely be a code such as DTC P0A78(32). This code is generated when the IPU fan drive module encounters a problem with the fan, its throttle or even the connection to it. Its pretty smart. ;)


    Cheers;

    MSantos
     
  13. Kacey Green

    Kacey Green Well-Known Member

    For the 2nd gen HCH the IMA fan was moved into the electronics box, making it quieter. Also at low speeds it becomes nearly undetectable, especially when compared with the first gen HCH.
     
  14. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    I don't think I've ever heard our battery fan. We usually have the regular passenger compartment ventilation fan running, which would tend to mask it, I guess.
     
  15. Kacey Green

    Kacey Green Well-Known Member

    I thought I heard it once but it was the Navi unit's fan or maybe the DVD just spinning away in there, but it sounded like a fan.

    There was one really hot day where I heard my Prius' fan and it performed like something was horribly wrong but no lights or anything, back when I was visiting my old co-workers at the 'yota store waiting for my brother's high school graduation program.

    I don't think I've truly heard a 4th gen IMA fan clearly, definitely not a 5g fan, its been too cold yet.
     
  16. bdog

    bdog Member

    With the car parked, rev to ~3000rpm and you should get regen (3 or 4 bars). Hold it there for 10 seconds or so and you should hear the fan come on. I'm not sure if this will happen in all cases, but it has every time I've tried it.

    B
     
  17. Kacey Green

    Kacey Green Well-Known Member

    I'll have to listen the next time I have a good reason for a forced regen (like when a car is fresh off the truck but after the fuses have been installed)
     
  18. roncad

    roncad Member

    This seemed to work. I held it at 3000rpm for about 5 seconds and when I took my foot of the gas I could hear a whining sound come from the IPU behind the back seats. This is, I believe, the sound of the fan at a higher rpm.

    Thanks everyone for your input.
     
  19. Harold

    Harold Well-Known Member

    Kacey, Which fuses do they remove for the journey here? Might be good to remove these when not using the car for a couple mths..:) Hal
     
  20. Kacey Green

    Kacey Green Well-Known Member

    Pretty much just the dome light fuse. Someone posted the PDI instructions and it will name the fuse. On the Insight and the Fit they intentionally blow out a fuse and replace it with a working fuse at PDI.
     

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