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Prius c underseat main battery

Discussion in 'Prius c Main Forum' started by priusmatty, Jun 6, 2016.

  1. priusmatty

    priusmatty Active Member

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    Hi all,

    As I understand it, the main battery in the c is under the rear seat. I also understand that there is a fan on the side of the seat that blows and cools the battery. I have some questions about that cooling fan, if you do not mind.

    1. Is it always on, or does it turn off and on depending on the situation?
    2. How effective is it?
    3. Is there any sort of filter? If not, how do dirt and dust not get in there on the battery?
    4. Has anyone installed a filter for this reason?
    5. Finally, if there is no filter, is there a way to clean the fan and inlet and vent area?

    Thanks!
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    The fan stays off until battery temperature starts climbing, which is prone to happen in everyday conditions. Somewhere around 35C the fan will kick in at its lowest speed.

    If you're in hot weather, stop-and-go conditions, temps will climb and fan speed will start to step up. Most I've seen is fan speed 4 at around 45C.

    Not sure if there's a fan filter on the c. Our 2010 hatchback doesn't have one. Back a while I put in a vacuum motor filter, tucked in behind the inlet grill. Then, thinking it might be too flow restrictive, switched to just a fine screen, the material used for residential windows.

    You can clean the fan, it's worth doing periodically. It takes a bit of effort, s few trim pry tools, and ratchet-and-sockets are needed.
     
  3. priusmatty

    priusmatty Active Member

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    Ok thanks!
     
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  4. priusmatty

    priusmatty Active Member

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    Just curious: how do you all feel about this filtering solution?

     
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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    That'd work. I'm currently trying just a screen, a scrap of window screen, held to the inside of the grill by a couple of black thread loops.

    upload_2016-6-6_8-32-30.png

    This is the blower on a regular prius. You don't need to completely remove it to clean. Compressed air and something like a Q-Tip works for cleaning the blades:

    upload_2016-6-6_8-34-36.png
     
  6. priusmatty

    priusmatty Active Member

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    Good idea. So, you think the window screen, and/or panty hose, would not block airflow too much?
     
  7. Mendel Leisk

    Mendel Leisk Senior Member

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    It's debatable. I started out with vacuum clean motor filter material, as mentioned above. But got concerned about air flow. I'd rather err on the side of NOT restricting flow, letting more dust through. Especially if I periodically clean the fan.

    Toyota now offers a filter, and I believe it looks similar to the screen I'm using, ie: very open. It'll basically catch big lint, pet hair, seed husks, that sort of thing.
     
    #7 Mendel Leisk, Jun 6, 2016
    Last edited: Jun 6, 2016
  8. bisco

    bisco cookie crumbler

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    if you don't carry pets or the like, there's really nothing to be filtered.
     
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  9. priusmatty

    priusmatty Active Member

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    But I would imagine that dust would get in there, no? My computer fans get really dusty over time.
     
  10. priusmatty

    priusmatty Active Member

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    I saw another post here today (cannot find it now) where a guy did an electrical test with the cooling fan, with different filters, and was able to figure out the loss in power for each filter. I wonder how hard it would be to do that with panty hose as the filter?
     
  11. bisco

    bisco cookie crumbler

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    hard to believe dust would bother the fan. the only significant cooling issues i've seen are when the fans are clogged with foreign objects like fur. you have a cabin filter from outside, (except when the windows are open) so most of what gets in the cooling fan is from the interior.
     
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  12. priusmatty

    priusmatty Active Member

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    I guess what I mean is that dust can stick to fan blades, and they will become thick and nasty, like the blades of a ceiling fan.
     
  13. bisco

    bisco cookie crumbler

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    right. i haven't seen that yet, up to 135,000 miles. barely any coating on my neighbors 2004. might depend on where you live though.

    it's the same with my air and cabin filters, very clean.
     
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  14. Sean Nelson

    Sean Nelson Active Member

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    I haven't looked under the rear seat so I don't really know how the cooling air flows over the battery. But the bigger issue with dust isn't so much that it gets on the fan blades as that it gets on the surface to be cooled. For example if you have a CPU heat sink with metal fins over which the air is supposed to flow, a coating of dust on those fins acts like an insulator and can reduce the heat transfer pretty dramatically.

    Dust on the fan blades may look ugly, but it doesn't actually reduce airflow very significantly. A filter would help with both issues, but only if you clean it regularly. And if there's already a dust buildup then you need to make sure that not just the fan blades get cleaned, but especially whatever surfaces are intended to be be cooled by the airflow.
     
  15. priusmatty

    priusmatty Active Member

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    Good points! You are right. Do you think a single layer of ladies' panty hose would work well as a filter, and still allow airflow?
     
  16. Mendel Leisk

    Mendel Leisk Senior Member

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    Nobody knows a lot more than you, we're all just muddling along here. :)
     
  17. priusmatty

    priusmatty Active Member

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    Haha ok thanks :)
     
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  18. Sean Nelson

    Sean Nelson Active Member

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    My concern would be how quickly it would clog up, and that depends on your environment and how willing you are to inspect and clean it. The finer the filter, the faster it will clog and the more often you'll have to inspect and clean it. So it's really up to you, I think. Try it and see how it works for you. Just don't choose something that's going to require more inspection and cleaning effort than you're willing to put in, because that could lead to worse problems.
     
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  19. priusmatty

    priusmatty Active Member

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    Good point. I am definitely willing to inspect it daily even. My main concern is airflow.
     
  20. davidc83

    davidc83 Member

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    The cabin has its own air filter, and I would think if you choose to use the recirculation button on your AC, then the cabin air filter will catch most of the fine dust particles, and it is much easier to access and clean...matter of fact, cleaning the cabin air filter is part of the maintenance which is done when you take it in for its PM.
     
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