TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC
Start a Discussionhttps://teslamotorsclub.com/tmc/tags/

Normal Rate of Discharge

Discussion in 'Roadster' started by Tex EV, Aug 1, 2017.

Tags:
  1. Tex EV

    Tex EV Member

    Joined:
    Jul 20, 2015
    Messages:
    101
    Location:
    Houston, TX
    I just returned from an eventful month away from home (and Roadster) on the other side of the country, and am reviewing footage from a camera I set up to monitor the VDS. The car was left on June 29th plugged into its 120V connector on "storage mode". Ideal range was 175 miles. Just 21 days later, it reached 25 miles and was continuing to drop at 2-3 miles per day. A family member was checking on the house weekly and fortunately noticed this. I overnighted our Model S connector that we took with us and instructed them on how to hook it up via the CAN-SR, just before it reached 20 miles. The 120V connector obviously failed. It was either a dud when I plugged it in, or a freak lightning strike on the house 1 week into our trip did it in. Found out about the lightning today, after arriving home to find our brick chimney scattered across the roof. :eek: Is this a normal discharge rate for a Roadster sitting in a garage? Outside temps were in the 90s. This was the first time I'd left it this long without charging. Also worth noting, it was plugged in via the functioning Model S connector on July 24th. The charge history on the VDS shows that it consumed 101kWh from then until today (8 days) when I unplugged it... seems excessive.
     
  2. hcsharp

    hcsharp Active Member

    Joined:
    Jun 7, 2011
    Messages:
    2,776
    Location:
    Vermont
    What were the ambient temps inside your garage? If it's too hot the Roadster cooling system will kick in to cool the pack whether it's plugged in or not. If I had to make a guess I'd say lightning fried your 120v cable but the coolant circulator and possibly the HVAC system kept running due to high temps. When you hooked up the UMC I don't know what kind of outlet you used but 100kWh would be almost normal on a 120v outlet. Charging is very inefficient at low amps and low voltage. You may have also continued to use a lot of energy for cooling. The pump runs continuously when the pack is over 30C (86 deg F).
     
    • Informative x 1
  3. djf

    djf Member

    Joined:
    Jul 15, 2015
    Messages:
    36
    Location:
    Santa Rosa, CA
    Short answer: I do not think this is a normal discharge rate for a sitting Roadster, by a long shot.
    Long answer: You are right to be concerned as this does indeed seem excessive. I routinely leave my Roadster (a 2008 1.5 just like yours) for 1-3 months whilst traveling and typical discharge rates are 1-2 miles/day of ideal charge for the first week or so, then about 1 mile/day. This is typically in the mild winter in CA. If it was hot (over 80 degrees F) in TX when you were gone then I would expect more drain, but I certainly would not expect it to be as high as you are reporting. I have observed my car's discharge rate when I am home in very hot weather when the coolant pump runs almost continuously and it is not much different from what I noted above. When traveling and leaving the Roadster in storage mode I plug into my Level 2 charger (Roadster UMC or sometimes my Clipper Creek J1772 with Henry's marvelous Can JR) and it kicks in reliably to keep the range above 30. But fortunately it takes a long time - 3-4 months - to get down to that level due to the low "vampire drain" discharge rate as described. Though note I get high 180s to low 190s ideal miles on a standard charge, so I'm starting from a high point. Overall I've been very impressed with and reassured by the vehicle's ability to hold a charge - though I always have a friend keep an eye on it just in case! Good luck and I think whatever happened to cause such a high discharge rate was an aberration and not the norm. BTW I find that the charger comes on for only a few seconds every 24 hrs when in storage mode - it essentially senses and then shuts off if the range is above 30 or so. It only stays on and charges when the range is below 30, after a good 3 months or so.
     
    • Informative x 1
  4. gregd

    gregd Active Member

    Joined:
    Dec 31, 2014
    Messages:
    1,222
    Location:
    CM98
    I did a short test run back in February, wondering how much I was spending just on vampire loss keeping yet another computer running 24/7. Over the course of 9 days, 5 hours, the car charged a total of 5.08kwh on a Standard charge setting, keeping the car at about 172 miles of ideal range. This was on a 120v circuit, 20 amp charging, as monitored by a "Kill-a-Watt" meter. The garage is unheated, but surrounded on two sides and the ceiling by the house, so it never gets terribly cold.

    My monitoring was from the wall plug. I think the car's charging report is slightly lower than this, as I think it's measured by what goes into the battery after the on-board charger. Not sure about the battery cooling, but that shouldn't have kicked in on a 120v charge. So, your number should be a little lower than mine, if the two cars were otherwise equal.

    So if this is at all representative, your car shouldn't have consumed more than about 12kwh during your 21 day absence, on a 120v (inefficient!) circuit. Less at 240 v. Normal loss for me is about a mile per day if the car is just sitting there, unplugged.

    I'm wondering if your car didn't fry something with the lightning strike? Usually it's the most expensive component that fails, saving the life of the $0.02 fuse. Either that, or your garage / car is sitting in a very hot environment, so it's running the A/C to keep the battery cool. Again, my garage isn't conditioned, but even with the outside ambient peaking at 100F during the day, the average seems to be low enough that the car's A/C doesn't kick in on its own (only while charging). There's a lot of thermal mass in the ESS, so I don't see it change much over time while the car just sits there. (The VDS shows it in the second block from the left.)

    All that said, my car is a 2010 2.0 non-sport, so perhaps the 1.5's have a different discharge characteristic? Is the coolant pump running continually, for example? Mine does not.

    Hope this helps!
     
    • Informative x 1
  5. Tex EV

    Tex EV Member

    Joined:
    Jul 20, 2015
    Messages:
    101
    Location:
    Houston, TX
    Made a short video of the VDS over 3 weeks:


    That's very likely what happened. Being a 1.5 with no 12V battery, the dashcam runs only when the car is on (running coolant pump and HVAC). There was a lot of footage captured on the warmer days.
     
  6. dhrivnak

    dhrivnak Active Member

    Joined:
    Jan 8, 2011
    Messages:
    2,496
    Location:
    NE Tennessee
    My 1.5 lost about a mile a day on the original battery. So this seems high. On the 120V charge cord the GFI can go bad but fortunately it was easy to replace.
     

Share This Page