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50 amp circuit only charging at 30amps with juice box

Discussion in 'Model S: Battery & Charging' started by Altes, Mar 6, 2017.

  1. Altes

    Altes Member

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    finally got 240v in garage and bought a juice box pro 40 charger. Problem is it started out at 40 amps (28mph) and after I set it up on the JuiceNet it now charges at 30amps max. Wondering why. Anyone??
     
  2. Cosmacelf

    Cosmacelf Active Member

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    That sounds like Tesla limiting the amps because it detected what it thought was substandard wiring or connectors.

    I've never been impressed with Juicebox, they cut corners.
     
    • Helpful x 1
  3. scottm

    scottm Active Member

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    Why wouldn't you just use Tesla UMC charger? If you have 240V and a NEMA 15-40 adapter on it... you can pull up to 40A on a 50A circuit breaker protected wiring and socket.

    What does JuiceNet offer?
     
  4. Rocky_H

    Rocky_H Active Member

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    A lot of people want some kind of wall-mounted option at home so they can keep their mobile cable in the car. (I thought this discussion has been done many times here.)
     
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  5. Rocky_H

    Rocky_H Active Member

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    Yeah, I'm pretty sure @Cosmacelf has it. That reduction from 40 down to 30 is the telltale sign that the charging system in the car detected a problem and is trying at a lower level for safety.
     
  6. brkaus

    brkaus Active Member

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    Sounds like a
    I believe that JuiceNet offers -
    - Shared charging (like HPWC). Two can coordinate using 40A total for example.
    - Reporting features - power used
    - Timed charging - ensure Time of Use is honored.

    I haven't looked at it a while. This is from last years memory.
     
  7. davewill

    davewill Member

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    You should try the UMC to see if you get the same symptom. If you do, look at the wiring, if not, have someone look at the Juicebox.

    Over in the other electric car forums, lots of folks have Juiceboxes and I haven't noticed any particularly large volume of complaints. Certainly enough people here report problems with UMCs. There isn't a single EVSE brand out there someone hasn't had a complaint about.

    Pot, meet Kettle.
     
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  8. brkaus

    brkaus Active Member

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    I think people here are on the right track. The first thing to try is disconnect the car from the charger. Set the car to full amps on the charging screen to 40A (or max it will go: 40, 48, 72, 80). Plug in and watch the charging screen. Does it ramp to 40A and then drop down? If so, that would imply the car is detecting a wiring problem and reducing the charging rate.
     
  9. scottm

    scottm Active Member

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    If I had two EV's (and will when Model 3 lands in the stable)...
    - use the same old fashioned HPWC to plug in one car or the other, physically switch over when needed.
    - I have an energy consumption monitor already, clips around the main feed at the main panel. I see the 19kW jump when HPWC fires up to 80A. This monitor has recording and online viewing and blah-blah features for computing cost of electricity. Really, it's too much tech for a simple need, but it only cost $100 and covers the whole house! I could move the unit to sub-panel in garage and monitor just the Tesla(s).
    - For controlled timing of charging, use the time feature of Tesla schedule in the car. I never use that because our power company doesn't charge more for electricity based on hour of day.

    I guess if I wanted to charge both cars at the same time... I would use one UMC plugged into the NEMA 14-50 outlet I have installed beside the HPWC and dial down the HPWC car to 40 or 50 Amps and let the other car go the full 40A on the UMC at the same time... this would not overload the garage sub-panel that is rated 100A.
     
  10. DarkMatter

    DarkMatter Member

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    And other people might want to do other things. Otherwise you would not have gotten a choice of colors for your car.
     
  11. gfunkdave

    gfunkdave Member

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    My concern with the JuiceBox is what happens to it if eMotorWerks goes out of business or decides to cancel JuiceNet access. Will it still charge like a non-connected charger?
     
  12. SageBrush

    SageBrush Active Member

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    Clean kettle, meet dirty pot.

    I'm not any help here but this sounds like a case of penny wise and pound foolish
     
  13. DFibRL8R

    DFibRL8R Member

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    I have a similar set up as you with a 100amp sub in the garage.

    I would (and will because I too have a model 3 on order:)) just use the scheduled timing feature to have the 2 cars scheduled to come on at different times during the night. Still use seperate circuits but less time where I'm pulling 80amps and risking higher temps in the wiring etc.

    Also physically switching the same HPWC sounds like a bit of a hassle and also loses the benefit of leaving the car plugged in most of the time even when not needing to charge. The advantage of leaving the car plugged in is the vampire loads run off the house current and don't tax the 12v as much. Frequent cycling of the 12v to run the vampire loads (due to discharging and then recharge from the main pack over and over) is bad for 12v life. I'm out of warranty so I prefer to make them last as long as possible.
     
  14. DarkMatter

    DarkMatter Member

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    The JuiceBox Pro that we use for our other EV will happily charge the Tesla at 40A. It has the thicker UL rated cord rather than the thinner cord, which could be a factor.
     
  15. Rocky_H

    Rocky_H Active Member

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    But that's not how that works. It doesn't constantly draw a trickle of current through your charge cable to run vampire loads. Even when it is plugged in, the 12V battery does still support that low level drain for hours and hours. When the 12V gets low, it will engage the main pack again to refill the 12V. It's a safety thing so that when the car is parked, it can leave the contact switches open and not have 400V energized throughout the car.

    The house electricity is only involved the next time it gets around to your charging cycle and if the main battery level is down at least 3% from your target, or if you turn on the climate control, that is too much draw for the 12V to support, so it will draw through the charge cable for that.
     
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  16. scottm

    scottm Active Member

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    I was also going to comment on the false thought of vampire load being "fed from the charge cable". It's not.
    Still cycles your main pack as mentioned...

    which is why I have a second plug on the Tesla... coming out the nose that hooks up a Ctek maintainer to the 12v directly. This one keeps away "needless" cycling of the wee battery and main contactors slapping 4 times per night... because the fat pack no longer has to maintain the wee beastie ... Eye!! Why am I am talking like at Scot all of a sudden? So the little maintainer also does wonders for keeping my parked charge level on the main pack where it was when I parked it... doesn't diminish overnight for "no good reason".
     
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  17. DFibRL8R

    DFibRL8R Member

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    Thanks for the corrections, I was going based on discussions I had read previously about why the 12v life is so short and how to prevent excessive cycling. I also recall Tesla at one time was recommending always leaving the car plugged in when practical. Seems like a poor design to excesssively cycle the 12v even if plugged in but, if true, I guess Tesla has their reasons.
     
  18. davewill

    davewill Member

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    Yes.
     
  19. arnolddeleon

    arnolddeleon Member

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    And very easy to verify, don't connect it to a network.
     
  20. arnolddeleon

    arnolddeleon Member

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    There are also programs to get paid for load management (stop or slow charging down).
     

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