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4% drop in SOC while parked 2 hours.

Discussion in 'Model S: Battery & Charging' started by randall_s, Apr 18, 2017.

  1. randall_s

    randall_s Member

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    Location:
    Meridian, MS
    I recently took a 200 mile trip with a 30 minute charge and 2 hour stop in between. I began by charging to 100% SOC and leaving immediately. My first stop was at an 80 amp charger, where I charged for 30 minutes from around 30% about 36% SOC. I drove to next destination and parked with a 32% SOC. I manually turned off the A/C to prevent cycling while getting stuff in and out of the car and left it parked for about 2 hours with an ambient temperature around 75 F. When I got back in the car to leave, it read 28% SOC and quickly dropped to 27%. I was a little worried because I had planned my trip based on the SOC levels and still needed to get to the hotel, which had a destination charger.

    Luckily, I had plenty of charge left to make it to the hotel, and charged to 90% overnight. When charging completed, I returned to the car, which reported a 91% SOC. Not a big deal, but I've never seen that happen before. I reset the charge level, thinking I set it wrong, but this behaviour continued until I set it to 88%, charged it, then 90% again next time. My 90% range estimate dropped from 245 to 241. I would think it just needed recalibration except I had just come back from a 300 mile round trip to Atlanta, exercising the SOC from 100% down to 25% or so and my 90% was still 245 after I returned.

    I spoke with the SC and they said the battery checked out OK. They said the battery was a bit warm (30C - is that warm?) and that the coolant loop was running. They confirmed the HVAC was off while parked for those 2 hours and really didn't give me any useful answers. 4% would be a 1.5 kW average draw over 2 hours - about like running the A/C. Anyone else have a similar experience?
     
  2. kort677

    kort677 Active Member

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    How many apps do you have connected to the car? I've found that some of these apps query the car often and that they do a lot to increase the vampire losses
     
  3. randall_s

    randall_s Member

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    Just the standard Tesla app. Though I can't imagine it (or any app) pulling 1.5 kW :)
     
  4. sorka

    sorka Active Member

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    Do you have cabin overheat protection turned off? It's enabled by default and 75F outside on a sunny day will definitely use extra juice unless you have the windows rolled all the way down.
     
  5. randall_s

    randall_s Member

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    Thanks Sorka. I do have it turned on though I don't expect it to pull much power. It wouldn't even need to activate the compressor as it could just pull in fresh air.

    If that was it, it would mean I had 2 issues (possibly 3). 1. overheat protection pulling 1.5kW 2. Charge controller not stopping at 90%. 3. 4 miles lost on estimated range. I know these things aren't necessarily related, but it's quite a coincidence that they all coincided.

    My first thought was that one of the 16 battery modules failed, but Tesla said my battery health is OK. I've come across some DIY interface involving OBD2 and Arduino, but it looks like quite a bit of work. Has this been refined? Would be nice to see what my car's up to.
     
  6. sorka

    sorka Active Member

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    Not sure if I would totallyy trust tesla on their assessment. They're not in the business of volunteering info that would result in you demanding a battwry replacement just because of ylost 4%.

    Get tm spy app and make the obdii to USB cable that everyone else has. not much work.

    I've had overheat protection zap 2% in 3 hours so 4% in two hours seems a little high.
     
  7. randall_s

    randall_s Member

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    Thanks. I just tested it out. I'm seeing all 96 bricks registering a voltage, so that's a good start.

    Screenshot_20170503-142559.png
     
  8. Electric700

    Electric700 Active Member

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    What about making sure that Energy Saving is enabled and Always connected is disabled? These settings should help.

    I also have Range Mode set to off, which may cause the car to use slightly more energy due to battery temperature system management.
     
  9. Max*

    Max* Autopilot != Autonomous

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    While I agree that those settings would help, that doesn't address the [potential] underlying issue.
     

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