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HPWC charging at 40 amps - (Resolved)

Discussion in 'Model S: Battery & Charging' started by Bruce, Apr 10, 2013.

  1. Bruce

    Bruce Member

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    Just had my electrician put in a 100 amp circuit and install my HPWC. plugged it in and cannot get the car to charge above 40. I manually moved it to 80 and it immediately bumped back down to 40. anybody got some ideas?
     
  2. Jeeps17

    Jeeps17 Cath Jockey in a P85

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    #2 Jeeps17, Apr 10, 2013
    Last edited: Apr 10, 2013
    I am assuming you have twin chargers. One possibility is that one of them is faulty, and that you are charging using the functioning one.

    Tesla should be able to diagnose this for you remotely.

    Another thought:

    Although I do not have a HPWC, I remember reading that Tesla is advising owners to limit their charging using them to 60A for the time being. Have you tried that amperage?
     
  3. Bruce

    Bruce Member

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    Never quite understood the twin charger thing, but yes I did buy that option. So - that said - I'll give them a call in the morning… Although I have successfully used the superchargers...
     
  4. MitchL

    MitchL S#945

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    Are the switches inside your HPWC set to say you have a 100A breaker?

    /Mitch.
     
  5. Banahogg

    Banahogg Member

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  6. clmazin

    clmazin Member

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    I had the same issue.

    Two things to troubleshoot.

    FIRST: cycle the breaker servicing your HPWC. Then try and charge at 80A. If that doesn't work...

    SECOND: check the dip switch settings inside the HPWC and make sure they're set for a 100A feed. If they're not, adjust them per the manual, and then cycle the breaker again.

    Thanks to FlasherZ for the breaker tip.
     
  7. wstuff

    wstuff Junior Member

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    The new software update did the same to me but @ 60 amps, the notification said I would be allowed to charge @ 60 instead of the 80 I was charging at until an upgrade was done to my HPWC to protect the internal fuses.
     
  8. Bruce

    Bruce Member

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    Thanks MitchL, Banahogg and Clmazin! I was ignorant enough to think my electrician would read directions… I had unrealistically left the work up to the guy who charged me $2500 to run the line and install the charger… He had not read or tested. I took it apart, read the directions, and now it works. Just hope it stays at the 80 I set (keep hearing people have trouble making it stay at 80…).
     
  9. brianman

    brianman Burrito Founder

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    Twin chargers and supercharging are unrelated options.

    What's the 6th digit in your VIN? A, B, C, or D?

    5YJSA1_

    I'm guessing C.
     
  10. UMD86

    UMD86 Member

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    Was the problem the DIP switches? Did you have a difficult installation? Had my HPWC installed today with a new sub panel plus permit and my cost was $940.
     
  11. Jason S

    Jason S Model S Sig Perf (P85)

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    Had the install recently and two things to note:
    1) I recall the default for the switches is 'test mode' -- that doesn't charge the car.
    2) turn the power off to the HPWC when changing the dipswitches -- they don't react (prolly a good thing) when power is going to the HPWC, but it will take the new setting on reboot.

    Additionally I'm using 60A until Tesla sends new fuses (or w/e ends up being the fix). I haven't had a need for 80A speed yet.

    - - - Updated - - -

    The problem is blowing fuses when running at 80, from what I've heard/read. Run at 60 is safer, especially if a long run of wiring with an electrician you don't exactly trust now.

    I've run mine at 80A but I 'helped' my electrician through the entire install so I know exactly how it went. Thick copper, only a few feet from a new breaker... thing should handle 80A easily, but I'm running at 60A because I expected better charging efficiency based on Roadster reports (complete WAG on my part) and because of reports that Tesla is recommending 60A until something is changed about the chargers (best guesses think it is faulty fuses).
     
  12. tomsax

    tomsax Member

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    Do you mean this report on Roadster charging rates and efficiency? I would expect the best efficiency at the highest charge rate, although for the Roadster there's not much difference between 32A and 70A. (I attribute the small differences in that range mostly to measurement error/random variation.) It's just the lower charge rates that have noticeably lower efficiency.

    The issue is charging overhead. It takes energy to run the coolant pumps and fans, so the longer your charge the more energy you spend on those items. In really hot weather, the higher charge rates might increase the overhead, but I haven't measured that effect. On the other hand, it seems reasonable to expect that lower charge rates are a tiny bit nicer to the battery, but even the maximum Level 2 charge rate is pretty mild on a Roadster or Model S battery.

    For all of these reasons, I charge our Roadster at 32A, which is the slowest rate I can use without a noticeable efficiency penalty.
     
  13. Bruce

    Bruce Member

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    5yJSA1D
    Why?
    WHat does that mean?

    - - - Updated - - -

    The DIP switches solved the problem.
    No, the installation went fine. He had to run the line approximately 100 feet under the house (crawl space) from the main panel and then approximately 20 feet from the Tesla subpanel to the controller. Probably all the line run...

    - - - Updated - - -

    By the way, since the line I ran is for 100A, I set the DIP switches for 100. The car is charging at 60A.
     
  14. tezco

    tezco Sig P85

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    Don't forget that continuous loads (more than 3 hours) require a derate to 80%.
     
  15. brianman

    brianman Burrito Founder

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    Sorry, didn't mean to be cryptic but forgot to post the link.
    Decoding Tesla Model S VINs

    D = 20kw Charger, w/DC Fast Charge

    So you've got the Twin Chargers; that's not the issue.
     
  16. FlasherZ

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

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    The HPWC handles this in that the DIP switches are set to the branch circuit size (max 100A).

    Technical note: it's not a de-rate to 80%, but rather an oversize to 125% (210.19(A)(1)). Same result for a single calculation, but it can affect math calculations if you have to apply other de-rating later. Also, article 625 throws out the 3 hour criteria for continuous loads and declares that all EV charging loads are continuous regardless of timeframe.
     
  17. tezco

    tezco Sig P85

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    If you have a "standard" 100A branch circuit you want to use for an EV, do you have to replace the breaker with an 80A to properly protect the circuit? If you then set the dipswitches to 80A, will you risk unwanted breaker tripping, or is the current draw slightly less to avoid inadvertent trips? (Don't know how breakers handle continuous loads right at the rated amperage.)
     
  18. FlasherZ

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

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    No. Breaker, conductors, and terminals/lugs must be rated for 125% (100A) of continuous load, which is 80A max on Model S.
     
  19. tezco

    tezco Sig P85

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    #19 tezco, Apr 16, 2013
    Last edited: Apr 16, 2013
    I guess I was confused by the mention of dipswitch settings of 100A. So the HPWC can be set to 100A, but the system is legal since the car can only draw 80A?

    updated

    That installation manual is a bit lacking. Perhaps I don't understand the dipswitches. Do they set the maximum output, or do they set a derated output based on the input circuit?

     
  20. FlasherZ

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

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    The DIP switches set your branch circuit rating, which is 125% of the current drawn by the car; or, the car knows to draw 80% of what the DIP switches are set to.

    I don't use "derated output", that term is incorrect in the context of the NEC here.
     

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