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UMC throttling back to 10amps on 14-50 ??

Discussion in 'Model S: Battery & Charging' started by tccartier, Aug 25, 2017.

  1. tccartier

    tccartier Member

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    AZ.
    Have tried everything I could think of "including calling support". My UMC will initially ramp to 40 amps (once) then throttles back to 10 amps within a minute or so on multiple 14-50 outlets at different locations. Charging at 7 - 8 MPH. is not going to cut it! On most recent plug in "tonight" it would only ramp up to 10A and the car won't let me raise the amps. on the main screen???

    It did work "once" @ 40 amps. ( it ramped up on it's own ) while I was on hold with Tesla service who told me when looking at the car there were no faults but that the pack temperature was "on the high side" ?? But now that I'm home .. same result, only getting 8mph 10amp charge rate off of a "known good" 14-50 outlet with my UMC.

    It should be noted that my Clipper Creek has no problem sustaining max. output "30amps" to the car and the car likes it! (off the same outlet).

    My UMC is still plugged to the car currently showing 241V @ 10Amps ??? What gives???
     
  2. shokunin

    shokunin P85 & S40

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    Did you try unplugging the nema 14-50 "adapter plug" and checking the pins? One time (3 years ago?) I had a UMC die out due to some arcing and the pins were burnt. This was before they recalled the adapter ends. Local service center replaced the whole UMC and it's been working fine since.
     
  3. tccartier

    tccartier Member

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    Update! my best guess is that it is throttling back because the battery pack temperature is too high I noticed that the shutters open on the front of the car but only the left side fan motor runs the right side does not. I reached in and touched the radiator to see if it was hot indeed it was, too hot to remain in contact with.. time for it's first service visit I guess.
     
  4. animorph

    animorph Member

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    Also look at the voltage as seen by the car in the charging screen. The UMC could have a bad connection somewhere causing a voltage drop that the car is seeing. Check (carefully!) to see if a particular part of the UMC is hot. Seems like a UMC problem.
     
  5. tccartier

    tccartier Member

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    Voltage range As observed during the time 236-241 fairly steady. But I did notice that the right side shutters were open on the front of the car but the fan was not running don't know if battery pack temperature is too high and unable to cool. When I placed call to Service Center and they took a look at the car remotely they did notice battery pack temperature was on the high side but I'm not sure what that means what is the high side? How high is high? And at what point May charging amperage taper off to compensate for a battery pack that's too warm?
    When I use my Clipper Creek the car does not throttle it takes maximum output but everything does get extremely warm or maybe I'm just not used to how warm things get charging at these amperages coming out of a volt which was maxed out at 16 amps
     
  6. whitecotton

    whitecotton Member

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    The fans are on the same control loop, so if one isn't running you have a fan failure. The Front louvers are also controlled together. The radiators behind the louvers are for the HVAC system which I can almost guarantee isn't actively cooling the battery while charging on UMC unless you just got off the autobahn. Im surprised they couldn't see the fan failure remotely if it is in fact not running.
     
    • Informative x 1
  7. tccartier

    tccartier Member

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    I was wondering why they could not see it as well?? Oh well I think I have two distinct problems, 1. A failed / failing Mobile Connector and 2. A non functional cooling fan motor on the right side. As I understand it... Those fans can and do run "at times" while supercharging.

    They said they are going to see if they can get a ranger out here to diagnose and or repair. Not sure a service ranger can do a fan motor on site if access is not possible be removing the inner fender (which I suspect it is)
     
  8. Rocky_H

    Rocky_H Active Member

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    I think I agree that you do probably have those two problems.
    Service Rangers can surprisingly do just about everything to the cars onsite, as long as they don't require a full lift to remove the battery.
     
    • Informative x 1
  9. dragoljub

    dragoljub Member

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    I had similar issues and re-seating the plug into the car helpf also make sure your plug in the car is clean.

    I have often wondered if letting the car charge slowly at 10 A is somehow beneficial to the battery versus keeping it at 40 there's plenty of time in the eight hours of night to charge the car
     
  10. jerry33

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

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    The slower the charging, the cooler the battery is while charging. However, charging at a very low rate is very inefficient. 33 amps is what I charge at normally. It seems a good compromise between efficiency and heat. Note that where I live, the electricity is not particularly stable (doesn't actually go out, but it fluctuates), so if the charge level is set at 40 amps, it will sometimes auto-lower.
     
  11. Rocky_H

    Rocky_H Active Member

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    Even at 40A, that's still a little less than 10kW. The Superchargers run at 100ish kW, so from the battery's perspective, it's still hardly anything, and it won't care. There is still possibly some value to it for a different piece of equipment. The mobile charge cable is made for 40A maximum, and it does get a little hot at 40A. I have mine set at 31A at home to keep it cool and not do as much thermal stress on the cable, which could shorten the life of the electronics in it some. Also, if you have one of the older cars with the 40A charger internally, I would think a similar thing applies with not running it at its maximum level too. The newer cars have the 48A charger inside, so 40A probably isn't a big deal there, but I wouldn't run the UMC at maximum for daily constant use. The same kind of thing would apply for a wall connector rated for 80A max, where it gets kind of hot at that level too.
     
  12. tnt1971

    tnt1971 Member

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    I had this exact issue, except that mine would drop to 25-30 amps and fluctuate after about an hour of charging. I brought it in to the local SC and they replicated the issue. They also noticed the resistor was getting really hot in the UMC and diagnosed it as faulty. They replaced the UMC. They said it was hot to the touch. The UMC has sensors and automatically reduces its charge rate when it gets hot. See if any part of it gets hot while charging and that may diagnose your problem.
     
    • Informative x 1
  13. tccartier

    tccartier Member

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    Thanks for the information. Yes it gets quite warm such that you would feel discomfort to the palm of your hand if you maintain contact with it, Not such that you need to release it but enough to be uncomfortable to the touch such that most would not want to hold onto it. "Realizing that such references are fuzzy at best due to the pain threshold one can endure as opposed to another"

    Oddly enough though the last time I tried it, there was no issue and the UMC ramped to 40 amps and remained there for approx. 2.5 hours of charging "before I had to unplug to use the car". During that time however it got what I would consider VERY hot in its entirety meaning the body, cable, and plugs both at the outlet and at the car.

    Fortunately I don't need to rely on my UMC as I have a Clipper Creek solution installed at home. I have a service appointment set up for next week to address this "and other issues" discovered since I took delivery. Hopefully I can get it diagnosed and resolved.
     
  14. tccartier

    tccartier Member

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    Update, problem got solved on service visit technicians performed the necessary tests and looked at the car's logs and determined that the mobile connector had failed they replaced it with a new one also got all my other issues taken care of as well in the same visit. Cudos to the Tempe maintenance team!
     
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