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False Positives With FW 5.8.4 Charge Current Reduction?

Discussion in 'Model S: Battery & Charging' started by Mayhemm, Dec 31, 2013.

?

Have you expeienced charge current limiting?

  1. No, I have not encountered this.

    59.5%
  2. Yes, my home charger has tripped this warning falsely

    31.9%
  3. Yes, my home charger has rightly tripped this warning

    1.8%
  4. Yes, a public charger has tripped this warning falsely

    6.1%
  5. Yes, a public charger has rightly tripped this warning

    0.6%
  1. Mayhemm

    Mayhemm Model S P85+ "Lola"

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    #1 Mayhemm, Dec 31, 2013
    Last edited: Dec 31, 2013
    Firmware version 5.8.4 introduced a new feature where the car will automatically back off the charge current by about 25% if it detects a problem with the circuit (exact criteria for current reduction are unknown at this time). This is presumably a reactionary addition in response to the recent garage fire incident.

    Some people have reported occurrences of the car reducing charge current when it shouldn't be doing so. In other words, getting a false positive on the condition of the charging circuit. Effectively, this would unnecessarily reduce charging capacity to ~75% of previous levels.

    Can people who have experienced this please report below so we can get an idea of how widespread the problem is? Please provide details about your charging situation (typical normal rate, reduced rate, type of charger (UMC, HPWC, etc)) so we can see it there is a commonality to any false positive readings.

    P.S. Could a mod please correct the spelling on my poll title? Thanks.
     
  2. mknox

    mknox Well-Known Member

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    I have not yet seen the behavior and I have charged at some public 90 amp units with voltages below 200. I do not have a HPWC and charge at a reduced rate at home, so cannot comment there. I would hope it senses more than just "low" voltage and that it has to see some rapid spiking before lowering the rate.
     
  3. efusco

    efusco Moderator - Model S & X forums

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    I answered yes and tripped falsely...but how the heck would I know if it was false or not? AFAIK the connection is good...it's actually a 6' run from the breaker on appropriate gauge wire and a brand new connection and the voltage seems stable and I've had no past issues on this particular NEMA 14-50, but there's no way I can know if there were voltage variations.
     
  4. bluetinc

    bluetinc Member

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    Mayhemm,

    Could you define what a false positive looks like? Are you simply assuming that because you were able to charge at a specified rate in the past at a location and now you are not? I'm not sure if "there wasn't an issue before, and now it thinks there is" is by definition a false positive.

    Because this is a technical issue, I think we need to get very detail oriented if we are going to discuss causes for trips, and false positives. I suggest collecting the following information from anyone who has had a "trip".

    (Chargepoint info)
    Location(Home/Work/Etc.):
    Original Charge Current:
    Type of Outlet/Charger:
    Wire gauge size and run length to Outlet/Charger:
    Has the installation been re-verified to meet NEC, with all connection point properly torqued, and outlet not worn:

    (Charge Cycle info)
    Voltage at car without load:
    Voltage at car with full current, immediately at start of charge:
    Voltage at car with full current at 5 min:
    Voltage at car with full current at 15 min:
    Voltage at car with full current at 1 hour:
    Charge time that current backed down, and backdown current:
    Other notes:





    Peter
     
  5. robaross

    robaross P4550

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    Before 5.8.4 I was charging at 32 amps with a max of 40 amps. Now I can only charge at 28 amps, with a screen indicated max of 30 amps. This is occuring automatically. I rebooted 17" screen which restored the 40 amp max, but when I subsequently charged it dropped back to 28 amps with a max of 30 amps. As others have stated, a licensed electrician ran the new line per Tesla instructions, installed 50 amp breaker, and I see approx 248 volts when starting charge, dropping to 244v during charge. Since this is at home home it is not a major problem but it is disconcerting.
     
  6. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    I have tried my UMC on a 14-50 that has a 0 current Voltage of 245 Volts and drops to 239 Volts with a 40 Amp load, and an HPWC that goes from 245 Volts to 239 Volts, going from 0 to 80 Amps. Neither showed a charging current reduction running 5.8.4 (1.49.57). Both are happy and keep charging at rated capacity.

    Both are in my second home garage. The 14-50 is about a 40 foot run of #6 Cu from the 200 Amp CB panel to the 14-50. The HPWC is connected with a 40' run of #2 Cu from the 200 Amp CB panel to the HPWC. All connections have been recently tightened.
     
  7. qwk

    qwk Model S P2681

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    Let's face it, this is a bandaid for a ****** UMC design. I don't know why a $100k car comes with a UMC designed to save Tesla a few hundred bucks per unit. I really doubt that someone paying $100k cares about the $500 extra it would take to get a quality mobile charging option. Without a charge your car won't do you any good. It's the most important aspect of the vehicle.
     
  8. Zextraterrestrial

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    I had one evening when my UMC dropped power to 30A. Techs said it looks like I had some 'flaky values on my proximity' and wanted me to use my other UMC and see if that was the problem. I have a load that pulls on one leg of my 14-50 and thought it could cause problems but I have turned it on/off and charging seems ok. I was logging on Visible Tesla when I had the A drop so I know when it happened just haven't figured out why yet & VT logs don't show any V spike
     
  9. Electric700

    Electric700 Member

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    I think Tesla's solution to have the car detect voltage irregularities was intended to be completely independent of the UMC, as some people might use another charging setup such as the J1772 to Model S adapter.
     
  10. qwk

    qwk Model S P2681

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    How do you figure? In the garage "incident", the car was charging on a UMC. There are a ton of documented, melted 40A adapter cases here. It isn't that difficult to make the connection as to why the firmware limitation was rolled out.
     
  11. Electric700

    Electric700 Member

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    Good points Qwk,

    It would seem likely that Tesla went that route because the change applies to any charger. This doesn't rule out investigating/fixing the UMC adapter issue(s) though I am not 100% sure if it's not a wiring setup related issue for at least some of the cases. May be other members have an update on that.
     
  12. mep

    mep Member

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    Chicago
    It was only today that I noticed that my 40A line only charges with 30A now. I can go to the car and set it back manually to 40A and it responds but after a while charging is back to 30A. A bit frustrating. The 50A outlet was installed by a professional electrician for a lot of money in a high rise only 4 years old. So old or faulty wiring can almost be excluded. Can this be the result of the new update?

    - - - Updated - - -

    Guess I just got the answer to my question. A moment ago car went back to 30A charging. Went downstairs to check and found two warnings. One of them informed me that charging has been reduced due to either extension cord use or faulty wiring. Restarted charging and it has now been stably charging at 40A for the last 10min. I am just glad that Tesla did not decide to turn of charging completely every time there is some fluctuation in the power line.

    - - - Updated - - -

    Nope, 15 min later back to 30A. Not sure what to do. Should I call that electrician who installed the outlet to check on the line? Will be interesting to see what he has to say.
     
  13. Mayhemm

    Mayhemm Model S P85+ "Lola"

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    Good points, guys. Unless you are an electrician, there's not really any way to KNOW you're getting a false positive. All we can do is report cases where we SUSPECT it is the case. Good examples of this are outlined in the replies by robaross and mep. They have strong reason to believe there is nothing wrong with the circuits in question (due to intimate knowledge of the installation) yet they are still seeing current reductions.

    For public chargers, you would have to go on the word of the proprietor. If they say the work was performed correctly yet current is still being reduced, then this would be considered a "public charger false positive". On the other hand, if a public site with reduced current shows obvious signs of neglect (exposed wiring, damaged charging equipment, etc) this would go under "public charger, current rightly reduced" in the poll.
     
  14. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    It would be great if you reported the Voltage before the current ramped up, and then the Voltage and current after the current has ramped up. Maybe a Voltage at 40 Amps and then after the fold back to 30 Amps. From the Voltage drop at load currents it is possible to get a rough estimate of the resistance in the installation and see if that is a threshold for the charge reduction.
     
  15. stopcrazypp

    stopcrazypp Well-Known Member

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    Yes, this is a good suggestion. Should be easy to report for those that have had it trip and should give at least an idea of the parameters for tripping.
     
  16. dirkhh

    dirkhh Middle-aged Member

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    I had the line checked by an electrician. There should be NO reason for the reduction. The voltage varies between 237 and 241 which is well within code (which suggests less than 5% drop). Still, as of 5.8.4 my Model S only charges at 30A.
     
  17. Cosmacelf

    Cosmacelf Active Member

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    Well, I just did a test in my garage. Started at 241V, ramped down to 235V at 40A from a NEMA 14-50. Charged at 40A just fine. On firmware 5.8.4 (1.49.57).
     
  18. riceuguy

    riceuguy Member

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    I had two Chargepoint public chargers show the error on the cars display and limit charging by 25%...frustrating! and Chargepoint chargers seem to be the common thread...
     
  19. Mayhemm

    Mayhemm Model S P85+ "Lola"

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    Heh, the only silver lining to that is no one in their right mind would roadtrip using Chargepoint chargers.
     
  20. Forty Creek

    Forty Creek Member

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    For the past three nights the charge from my HPWC was reduced and the car display a warning about bad wiring or extension cord use. HPWC wiring is straight forward and was properly done / inspected. We have just been through a severe ice storm and our area experienced total power loss for 3 1/2 days. Ontario Hydro crews worked tirelessly to restore power but I wonder if our rurally located home might be getting some voltage fluctuation due to changes at the road. I'll give Hydro a call in a day or two to ask if they could do some sort of check of line.
     

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