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Cannot seem to access top third of battery capacity

Discussion in 'Roadster' started by Volta, Oct 31, 2016.

  1. Volta

    Volta Member

    May 16, 2014
    Hong Kong
    So, here's my issue. Hoping someone can help out.

    Tesla recently replaced my PEM. Ever since I got my Roadster back (2.5 sport), I am unable to completely charge my battery. The charging automatically cuts out when the battery is showing around 60% full. It seems like I am blocked from accessing the top 40% of my battery capacity. The VDU shows "done charging" with the green charge bar showing around 60% full (around 160 kms of the 270 kms or so I generally get these days on a full charge).

    Hopefully, the above explanation of what I am experiencing makes (some) sense. Equally hopefully someone has some idea what might be causing this, and even more, knows what can be done to fix it so I can fully charge my battery again.

    Tesla initially thought my charge cable might be responsible, and very kindly replaced it (without charge). However, this hasn't fixed the problem. They will take my car back in next week to take a look. But a little worryingly they don't really seem to know what might be causing this. It seems to me that the system is blocking my access to the full capacity of the battery for some reason, and automatically ending the charge earlier, when around 60% full.

    Given the timing, I expect it must be something to do with the PEM replacement, as I had no problem charging to full before the replacement, but I have had this problem ever since.

    Thanks in advance for your thoughts ...
  2. gregd

    gregd Active Member

    Dec 31, 2014
    Wild guess here, but you might grab the logs and see if you're getting a bunch of 1146 errors (low fan speed) during charging. I've apparently got a slow fan, and notice that the charging seems to cut off a little early, 164 miles (about 70%), when it normally charges to 168 (83%). Leaving it plugged in, the next day it tops itself off to the full 168. I'm guessing that it senses enough bad stuff (heat) that it shuts down a bit early, then finishes after things have had a chance to cool down.

    A low fan speed can be caused by a loose or damaged PEM Fan connector, which gets disconnected when the PEM is removed, or the fan itself might be having a problem, or the ducting might not be making a good seal against the PEM housing.
  3. wiztecy

    wiztecy Active Member

    Apr 29, 2012
    Santa Cruz, California, United States
    #3 wiztecy, Nov 1, 2016
    Last edited: Nov 1, 2016
    Is that 60% battery bar for std mode or range mode?

    If you have a bad cell or sheet your battery is as strong as that, so if that sheet can only charge up to 60% then so will the rest of the pack. If the VDS says 'done' and no errors are displayed, I'd take it that the car charged properly and that issue resides in the ESS. The other issue is that your battery is way out of balance which would yield the same results.

    You should take a look at your voltage on your bricks/sheets as well as if its balanced or not to start, if that looks good then start moving to the PEM. But if the PEM is the limiting factor typically error messages and alerts will pop up.
  4. ggr

    ggr Roadster R80 537, SigS P85 29

    Mar 24, 2011
    San Diego, CA
    I wonder if your software thinks you have the upgraded battery pack? 3.0s in standard mode also only charge 2/3rds.
  5. hcsharp

    hcsharp Active Member

    Jun 7, 2011
    That was my first thought. Maybe the new PEM has the 3.0 hardware and was flashed for a 3.0 ESS.

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