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53kwh consumed in one charge

Discussion in 'Roadster: Technical' started by smoothoperator, May 5, 2012.

  1. I drove my Roadster in range mode yesterday and got back home with about 13 miles left. I have a digital sub-meter that displays load, total KWH & KWH consumed per session.

    To my surprise my Roadster consumed 53KWH in one charge! Has anyone else had s similar experience? Is there a problem with my meter or is this possible?
     

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  2. dsm363

    dsm363 Roadster + Sig Model S

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    I did the same thing yesterday (arrived with 20 miles) but only used 47 kWh. There is an overhead to charging so I think it is possible to use more energy to charge than your battery pack can hold.
     
  3. W.Petefish

    W.Petefish Active Member

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    Think cooling.
     
  4. Tommy

    Tommy Member

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    Even the Model S with it's built-in charger's 92% efficiency would require about 62 kWh to fill a completely empty 53kWh battery. So not surprising that the roadster's internal charger, which is less efficient would consume 53 kWh to charge your nearly depleted battery.
     
  5. pi.uhl

    pi.uhl New Member

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    Last month I had this one:
    20120428_000901.jpg
     
  6. dsm363

    dsm363 Roadster + Sig Model S

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    Wow. 88 kWh. Can that be right? What were the circumstances behind that?
     
  7. bonnie

    bonnie Oil is for sissies.

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    I'm betting a very hot day & a very hot battery. Even if you're not charging until later (when rates are low), should probably at least cool down the battery (instead of letting it sit there hot).
     
  8. dsm363

    dsm363 Roadster + Sig Model S

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    Do we having any guidelines on how many degrees is too warm? The OVMS lists the temps in Celcius so that would give some information.
    Do you just initiate a standard charge mode for half an hour when the battery is warm? Thanks.
     
  9. scott451

    scott451 KWH-PWR#1349Sprt,S Sig#96

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    #9 scott451, May 6, 2012
    Last edited: May 6, 2012
    Yes, it is.

    No. It is not caused by a hot battery :smile:

    I've seen this before on the roadsterVDS via the tattler charge reports. What I believe is happening is that the 88kWh and 15h:11m comes from two concatenated charges but with a drive in between. So the total energy used to charge is correct, but it represents two charges. Here is an example (as logged by the tattler):
    dual_charge.PNG

    Notice in the above picture, I finished charging: 243 miles, 96%, 41kWh 8:20 hrs used. I then drove the car about 80 miles (not shown). I started a charge at 3:22pm. Notice the battery has dropped to 67% and 148 miles (from the 80 mile drive). Five minutes later, I sent the "charge?" command to the tattler and the roadster reported 42Kw (41kwh from the previous charge and 1kwh from current charge. 8:20+5min). Had the roadster reset the count at the start of the charge, it would have reported "1kwh used, 0:05hrs".

    So the accounting of charge energy of the VDS appears to be correct, but some of charge history records are the concatenation of two charge sessions with a drive in between.

    So if the OP adds up all charging energy reported by the VDS (including the 88kwh) it would correctly match the reading of a wall kWh meter.


    As far as the OT, I drove 222 miles from Goleta to San Diego on 95% charge. IIRC, the battery temp was 39C and the energy required to recharge was about 65kwh.
     
  10. ChargeIt!

    ChargeIt! Member

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    #10 ChargeIt!, May 7, 2012
    Last edited: May 7, 2012
    I can confirm that some "bugs" related to CSH (Charge Session History) are still not fixed (in the 1.5 Roadster). And probably won't be ... Remember THIS ?

    And here's an additional photo from January 2010 ... notice the MANY things wrong with it back then. (The "Available Current" column was dropped shortly thereafter as part of some of the "bug fixes".)
     

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  11. Yea that is the reason I installed a sub-meter as I got several odd readings from the on-board meter early on. The trip meter also displays odd readings at times. I am not sure if these have been fixed in subsequent firmware releases (does anyone have release notes for firmware updates?) That is why I asked the question, as I thought my sub-meter was now malfunctioning :scared:
     
  12. vfx

    vfx Well-Known Member

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    In the early days it was determined there was a 20% hit on charging losses cooling etc. I usually tell people 53 battery and 64 charge.
     
  13. Doug_G

    Doug_G Lead Moderator

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    I pretty much ignore that screen. It gets confused.

    When I have a moment I'm going to add a feature to the Tesla Graphical Log Parser to display charging history. Not hard to do... just need to find a little time to do it.
     
  14. wycolo

    wycolo Active Member

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    #14 wycolo, Oct 27, 2012
    Last edited by a moderator: Oct 27, 2012
    attachment.php?attachmentid=5892&stc=1&d=1336439369.jpg

    I used to see this on my 2.0. Now I can't find it. Has it been eliminated by the July 2012 firmware upgrade?
    --
     

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