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Unwelcome change in charging rate

Discussion in 'Model S: User Interface' started by tezco, Jul 12, 2014.

  1. tezco

    tezco Sig P85

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    Just finished an update to 5.9 started about a month ago (been too sick to drive). Need to pull the car out of the garage tomorrow, but the iPad App wasn't working so I had to go out to the garage to raise the charge limit manually. Had completely forgotten that I had started the update last month. (App was still offline after finishing the update, so probably something more systemic in App-land I guess.)

    While I was in the charge screen I noticed the max charging rate had changed significantly from my customary 30 A setting (limited because of garage wiring). Charge current was now set at 80A! I've charged several times since begining the update, but I haven't sat in the car since late May or early June. Fortunately my rate is limited to 35A by settings in my J1772 EVSE; however, my wiring can really only safely allow charging at 30A.

    This unanticipated change in the charging rate could prove problematic to other users with similar wiring limitations, and I'd recommend that users check this setting after each software update. I don't know what happens when a updare runs during a charging cycle, but it is possible that the charging rate may increase during that charge if this glitch affects others.
     
  2. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    In 5.9, the screen will display 80, but it really will charge at whatever rate it was set to previously. You don't have to change it. It's a display oddity that will no doubt be fixed in some future release.
     
  3. Sparrow

    Sparrow S105/ Roadster 189

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    I've got this bug too, once or twice a month my car changes the charging rate upward to 80amps for no apparent reason. This is not just a display issue, I have checked the cable and it is extremely warm on these occassions.
     
  4. tezco

    tezco Sig P85

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    Oops, I didn't realize this had been discussed before in the 5.9 thread (p. 66 & earlier):
    I guess we could merge this with the 5.9 thread; however, it could be a safety issue if Sparrow's situation applies to others:
    Unfortunately I didn't have my data logger turned on, so I can't tell if Jerry or Sparrow's scenario applies to my S. If the screen flips back to 80 I'll run a charge with the data logger turned back on to see if I'm hitting the 35A limit set by my J1772. According to code, my wiring can tolerate this rate for a couple of hours.
     
  5. green1

    green1 Active Member

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    While this is definitely an unwelcome change, I have to ask, if you don't believe your wiring can safely handle more than 30A, why do you have a circuit breaker that allows more than that installed? I know having a dead car in the morning sucks, but your garage burning down from wiring that can't handle the current seems to me to be a far worse fate.
     
  6. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    I'd wonder why the breaker didn't trip immediately if the rate went up to 80 amps. 35 amps (on a 30 amp breaker) I can see the breaker not tripping for awhile because breakers aren't exactly scientific instruments.
     
  7. tezco

    tezco Sig P85

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    My EVSE won't allow the car to negotiate a draw of more than 35A. I have a 40A breaker on the circuit (needed to prevent nuisance tripping when I'm welding) but one segment of the wiring (a dryer cord connecting the EVSE to the 50A receptacle) is limited to 30A continuous (thus, it's not to code with that size breaker). So, nothing will trip with up to 10A of overcurrent, but that one segment of the wiring is definitely undersized for 35A continuous by code (that cord doesn't even get warm at 35A, but I don't run at 35A, just to be safe). When I finish pulling wire for 200A service to the garage I'll probably start using my UMC for a bit more power and leave the EVSE in place for the LEAF (which only draws 16A). If I decide to invest in a HPWC, I'd like to dial it back to 60A considering the number of reports of folks with hot HPWC handles. Sure would like any reduced current level that I set in the S to hold.
     

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