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Normal PEM Temperature

Discussion in 'Roadster' started by smicker, Jul 31, 2016.

  1. smicker

    smicker Roadster 1020

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    I suspect my PEM may not be being cooled properly. Can anyone share what normal PEM temp is during light driving (30mph) in 65-70° temps?

    --Paul
     
  2. hcsharp

    hcsharp Active Member

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    Assuming your light driving is not too much stop-and-go with hard acceleration up to 30mph, I'd say you should expect your PEM to stay in the low 30's C.
     
  3. Stefan T

    Stefan T Member

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    35C is the temp that the car try to hold if the pem is the hot part
     
  4. wiztecy

    wiztecy Active Member

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    The 1.5's run a higher temp than the 2.x's as ambient temp rises, which is normal. Especially against the 2.x's that have the dual blower upgrade. If the duct/PEM/Blower is clean and functioning as it should the temps drop and stay low on the 2.x dual blower system quite well. The 1.5 will also ride at times between at the last blue block, again normal, in higher ambient temps, ~85F.
     
  5. smicker

    smicker Roadster 1020

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    Thanks all. I have a 2.5 and I'm getting 38-40C (3rd blue bar) and this weekend was unable to charge at greater than 27A in 100ºF heat with a 'Charge Thermal Limit' error. I'm going to see what I get with an extended 65mph run this morning.
     
  6. wiztecy

    wiztecy Active Member

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    The 2.5's have the dual blower, so things should be able to cool down very well. I have a 1.5, but when I had a 2.0 with the upgraded dual blower I could see the PEM temp bars drop down significantly when it was kicking on. When was your last annual service and do you drive / live in a area that has lots of leaves, pine needles, etc? The 2.x PEM / Motor cooling system was a step backwards from the 1.5 in some sense, it picks up all the crap off the road and packs it into the PEM/Motor cooling areas restricting the needed air-flow to cool things down properly.
     
  7. smicker

    smicker Roadster 1020

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    Almost all of my driving is 880 between Oakland and Fremont so no real oppty for leaves to get caught. My last service was Feb and new appts for roadsters these days is 6+ weeks out these days so I may try a crack at self-cleaning.
     
  8. thefortunes

    thefortunes Member

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    The other factor that comes into play here (in my opinion) is what your battery and motor temps were during the times you referenced.

    Since the PEM is directly above the motor and behind the battery, it is also influenced by the heat coming off of them (i.e. if your battery is 35C I would not typically expect the PEM to be below that even with the most gentle driving). If you are driving 30mph I assume you are also hitting stop signs/lights which will increase PEM temp as you accelerate and decelerate (regen).

    A 3rd blue bar is normal for the PEM. A "charge thermal limit" error is obviously not - what were the battery and PEM temps when that occurred? How do you know it was limited due to PEM temp?
     
  9. dpeilow

    dpeilow Moderator

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    I'm getting PEM temps in the 40s (deg C). Maybe I should look into this.
     
  10. thefortunes

    thefortunes Member

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    Here is the chart of Motor, PEM and Battery temps for each bar (per Scott back in 2011). The last group 3.5.17 is hopefully still current.
    [​IMG]

    My PEM temps (ambient temp around 35C with high humidity) went from near 50C to <40C on my commute after I cleaned my PEM last week.
     
  11. dpeilow

    dpeilow Moderator

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    This was after a one hour drive, half an hour of sitting then another 5 minute drive. My passenger took this at 70 mph. Ambient temp was about 20C.

    IMG-20160805-WA0001.jpg
     
  12. thefortunes

    thefortunes Member

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    Those do appear high (even though they are still in the blue) - I just got home from a 30 minute drive at 70mph (ambient temp 28C) and my temps were motor:59C and PEM:40C.

    I would recommend cleaning the PEM, motor and fans.
     
  13. gregd

    gregd Member

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    Those actually are pretty typical of my car. The PEM, in particular, seems to have very little thermal mass, and can go up or down several notches within a minute or two. It will go from dead cold to mid-band between my driveway and the end of the block. Pretty consistent, before and after the yearly cleaning. Do we have something loose?
     
  14. DanielFriederich

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    50C is quite high for the PEM so I would suggest to consider a PEM and motor fins cleaning. If still under warranty let SC handle it, if not and you are able to hold some tools in your hands and know how to use a volt meter its a do it yourself thingi... ;)
    Did it once, took me several hours, but result was remarkable!
    Take a look into the sticky thread PEM cleaning for more info on it!
     
    • Like x 1
  15. dpeilow

    dpeilow Moderator

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    It's looking like I'm going to have to do a PEM clean, but I find it hard to believe as the car has barely done 3000 miles since the annual service.
     
  16. hcsharp

    hcsharp Active Member

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    Read the various threads about people who installed filtering systems around the fans. I have a large, non-restrictive filter that I made and I've put 10k miles on my car since the last cleaning a year ago. My PEM heats up no faster than it did a year ago. I live where there's lots of leaves, and a dirt road in the summer. This may not be the perfect option for many people but it's worked for some of us.
     
    • Informative x 1
  17. DanielFriederich

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    Henry. Can you provide picture(s) of your filter? I am wondering myself since a few months installing some additional hardware to the Roadster :D
     
    • Like x 1
  18. hcsharp

    hcsharp Active Member

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    I'll probably clean the filter out next month. Can you wait until then for the pictures? This is the material I used. It has very non-restrictive air flow and dust tends to stick to it.
     
  19. dpeilow

    dpeilow Moderator

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    Today I saw the PEM at 55C and motor temps up at 120C while just driving 60-70 mph on a back road.

    At one point I wanted to switch to performance mode to overtake but it never went white.

    Then to top it off I wanted to charge when arriving at home but the HVAC compressor pressure warning went off and I stopped that as the battery wasn't cooling.

    It was a lovely summer day with ambient temp about 24C.
     
  20. DanielFriederich

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    no prob Henry... I meanwhile consider taking the box out which is build around the fans since I drive mine only in good weahter conditions and I once drove it a few meters without the down plate and cooling was amazingly better probably due to a better air flow to the fans
     

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