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24 Hour Charging Timer

Discussion in 'Model S: Battery & Charging' started by Daniel Scherer, Feb 13, 2013.

  1. Daniel Scherer

    Daniel Scherer Junior Member

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    Location:
    Monroe, Michigan, United States
    I put this timer together tonight to test charging in Off Peak hours. Grainger PN 2E022.
    If I do a full ON Peak charge it's $15.47 or $0.046 per/mile, OFF Peak it's $6.54 or $0.02 per/mile for an 85kW battery.

    - - - Updated - - -

    Timer cost $60.11

    The whole assembly is less than $100.
     

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  2. cleanser

    cleanser Member

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    Bay Area, CA
    Nice we have a few of these timers for our building lights. Hopefully tesla updates the firmware so this isn't needed
     
  3. araxara

    araxara S-P85#3,218 X-90D#3,299

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    I have this same timer still on my wall next to a breaker panel. It was installed in 1997 to provide TOU power for my GM EV1. The timer is now bypassed in preparation for the forthcoming HPWC. These timers are built proof, but I think if I were to use one again I would switch to a digital one - seems more 21st century.
     
  4. brianman

    brianman Burrito Founder

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    Pics or it didn't... j/k

    Pics because I want to see 'em. :)
     
  5. araxara

    araxara S-P85#3,218 X-90D#3,299

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    1997 EV1 Deliver with Delivery Specialist, me and my wife. Or did you want to see a picture of the timer?:wink:
    EV1 Delivery.jpg
     
  6. we7313

    we7313 Member

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    Possible?

    I actually posted this in another thread, but it looks like this one might be more applicable for my question:
    Would it be possible to get a second meter and somehow have your house usage switch between the 2 to get the best rate for the given time?
    For example:
    Right now I'm not on a time of use plan and pay a flat rate of $0.13/kwh.
    If I go to a time of use meter I will be paying $0.05/kwh from 8am-8am.

    There is a $0.30 a day fee for the additional meter, but that should pay for itself quickly.

    So ideally I would like all house usage to be on the static $0.13/kwh rate meter from 8am-8pm and the switch to the time of use meter from 8pm-8am.

    Does anyone know if this is even possible?
     
  7. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    7,019
    A couple of things about this particular timer:

    First, the T103 has a 120V clock motor, so it will require a neutral conductor. For a 14-50 outlet it's fine, for a 6-50, you'll need a different model (T104).

    Second, the specifications sheet spells out a maximum wire size of #8. This means you can't use NM cable (Romex) with it, because a 50A circuit (40A continuous load) requires #6 for 50A circuit and the terminals on the clock can only handle #8.

    Third, and the biggest one, is that this timer is not approved for the loads that you're placing on it. While the timer says it's rated for 40A, NEC requires the rating for all equipment carrying continuous loads to be rated at 125% of the continuous load. This means you need a 50A timer (I was searching for off-the-shelf products the other day but didn't find any easily; most electricians can build them using contactors).
     
  8. Daniel Scherer

    Daniel Scherer Junior Member

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    Monroe, Michigan, United States
    Actually this is connected to a second meter dedicated to my car. DTE is giving me a discounted rate just below $0.08 per kWH between 11pm and 9am week nights and weekends.
     
  9. Daniel Scherer

    Daniel Scherer Junior Member

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    Good analysis FlasherZ. I'm going to drop my charger current down to 30 amps which should easily top off the battery each night.
     
  10. brianman

    brianman Burrito Founder

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    /envy your participation in history.

    Thanks for the pic, araxara.
     
  11. bellwilliam

    bellwilliam Member

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    may I ask how much it cost you to add a 2nd meter ?

    btw. this is a sad day when a 100k EV car owner need to build a timer himself by going to a Home Depot !!
     
  12. ElSupreme

    ElSupreme Model S 03182

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    Thanks I was going crazy trying to find such a thing for 50A circuit that didn't cost $400.
     
  13. Daniel Scherer

    Daniel Scherer Junior Member

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    Location:
    Monroe, Michigan, United States

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