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Uneven/laggy/misrepresented SOC at 110v

Discussion in 'Roadster' started by Slackjaw, Jul 16, 2012.

  1. Slackjaw

    Slackjaw Member

    Joined:
    Apr 12, 2011
    Messages:
    354
    Location:
    Central NJ
    I've noticed a weird effect while charging at 110 (in a rental). Here's the executive summary:
    • car had 70 ideal miles when I plugged in last night
    • this morning at 7 am when I stopped the charge, it read 111 ideal miles
    • after driving 8 miles to work it read 101 miles
    • a little while later (in this case, after being parked for 1 hr, not charging) it read 122 miles range
    I've seen this a number of times before but wasn't sure if I was going crazy. Apparently not. From a practical point of view, could it result in overcharging the battery? I don't think so because I recall that early on it stopped charging at [reported] 94% as if only the display was wrong. At least once before, I told it to charge after stopping at 94% or 95% and in only a few minutes it reported 100% charge.

    For trip planning it would be worse if it were the other way around - i.e. range dropping by 20 miles. Odd though. Anyone else seen this? Thanks.
     
  2. dhrivnak

    dhrivnak Active Member

    Joined:
    Jan 8, 2011
    Messages:
    2,150
    Location:
    NE Tennessee
    I have not seen this so i would guess there is some thing wrong.
     
  3. strider

    strider Active Member

    Joined:
    Oct 20, 2010
    Messages:
    2,920
    Location:
    NE Oklahoma
    It could be related to a delay in balancing after charging was stopped. I have noticed weird SOC behavior any time I halt it mid-charge. Anyway, at least the SOC went UP :)
     
  4. chronopublish

    chronopublish 2008 Roadster #VP27

    Joined:
    Jun 10, 2009
    Messages:
    45
    Completely normal. I've done most of my charging at 110V and am very familiar with this behavior.

    Any time you interrupt a charge in progress, the range displayed on the VDS will show as lower than it really is. The longer the charge, the greater the discrepancy. The car will automatically fix the number (increasing the range shown) after about 15 minutes of not being driven. This adjustment will happen even if the car is turned on, so you can sit in the parked Roadster and watch the range jump up if you're so inclined.
     
  5. Slackjaw

    Slackjaw Member

    Joined:
    Apr 12, 2011
    Messages:
    354
    Location:
    Central NJ
    Ah, OK - thanks for the experienced feedback! I was always charging at 220V/40A before and if the effect was there, I didn't notice it.

    Thanks again.
     

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