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DIY: Roadster 2.5 PEM cleaning - step by step

Discussion in 'Roadster' started by m0rph, Jul 19, 2015.

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  1. Mark77a

    Mark77a Member

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    Although I was joking when I said "Blockage = Crap / Area" ...

    There is truth in this. If the surface AREA of the filter is too small (ie ie same or similar Area to the cross section area of the air flow, then air flow will be restricted.

    This may cause problems:
    A) Lower amount of cooling air reaching motor and PEM !!
    and
    B) Higher current draw from the fan motors - which is bad for the connectors into the PEM, which are known to have marginal current capacity.
     
  2. Marius

    Marius Member

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    As far as I understand electric motors like this one, your statement is not correct. In case of not sufficient airflow the motor takes less current and you get an alarm dc fan problem 1146 meaning low amperage to motor. This is a kind of pre warning which tells you airflow is not sufficient, and if this is not solved eventually the PEM gets overheated. Because of bad contacts in connectors you can get reduction of amperage as well which brings the same notification 1146 active.
     
  3. Mark77a

    Mark77a Member

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    So restricted airflow is good ? ;-)
     
  4. hcsharp

    hcsharp Active Member

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    Restricted air flow is not good but @Marius is correct that the motor actually draws less current if the fans are blocked. While motors generally draw more current when they have to work harder, if a fan is moving less air then it won't be working as hard and will draw less current. This is especially noticeable with squirrel-cage fans.
     
  5. Mark77a

    Mark77a Member

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    True - However, when the fan has bits of twig and road debris in it, the current will go up :)
    This is why I am a 'big fan' :rolleyes: of large area filters before the air gets into the system.
     
  6. hallvardr

    hallvardr Member

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    While my PEM was out, I used the time to make filters for the fans.
    DSC_5218.JPG
    Netting to stop the filters from getting into the fans
    DSC_5219.JPG
    How much air they are letting through
    DSC_5220.JPG
    Finished products. In theory I should be able to change the filters without removing the fans by opening 2 screws and replacing 4 zips. But It might be just as fast to just take it out.
     
  7. warden_clyffe

    warden_clyffe Member

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    IMG_4259.jpg IMG_4259.jpg

    This is my final solution. I get no error-messages at all, similar grid as hallvardr is using.

    I have driven app. 800 km now with this filter, incl. light rain, high-speed an (ambitionned) curvy-roads - my PEM has never got into yellow temp-range (as before), same with motor.

    Off course PEM was cleaned complete before and I renewed the IGBT- insulators...
     
    • Like x 1
  8. hcsharp

    hcsharp Active Member

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    Nice work! Looks much more professional than the solution that I crafted.
     
  9. warden_clyffe

    warden_clyffe Member

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    as i have a supplier for those side-lids i'm recently working on a small series of those boxes - there's alittle change you have to do on the stabilizer-mounting, this needs a 7.5mm spacer (pics to follow), i'll make those as well either in alloy or corian
     

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