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Charge current reduced and increased during charging

Discussion in 'Model S: Battery & Charging' started by David99, Jan 30, 2015.

  1. David99

    David99 Active Member

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    I just noticed something very positive and encouraging. The Model S was always very picky about charging and reduced charging power when it detected anything it didn't like. There are some discussions about here. Not sure if it's voltage drop or whatever they are monitoring that can trigger the car to reduce charge current. Up until now it would only adjust down and never back up again. It would also not allow you to dial it up again during a charging session.

    Yesterday I updated the firmware to 6.1.115, the small update that came right after 6.1 was pushed out. I plugged in at a public charger and after about 30 min the car adjusted the current down from 30 to 22 Amp saying it detected bad wiring or an extension cable. I didn't bother restarting the charger. When I checked the charge status a few hours later it was back to 30 Amp! That's a first! The car never did that before. Not sure when they added that feature but that's excellent! I did notice the voltage was a little higher than when I plugged in. So maybe the increase in voltage made the car think it's OK to adjust the charge power up again.

    Just wanted to share that experience. Very good to see this is now implemented.
     
  2. Obsoletion

    Obsoletion Member

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    That is great if it is doing that. I am going to see if that happens at a location i have problems with and post back
     
  3. Forty Creek

    Forty Creek Member

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    I just posted the same observation over on 6.1 for Classic MS. Captured the behavior last night using VT.
    Started charging at 7:05 PM and the car went to nearly 80 amps, then dropped 25%. Soon after, it went back to 80 amps and dropped again. Stays at 60 amps most of the time but went back up to 80 briefly before dropping one last time and finishing the session at the lower rate. Tesla service told me that an 8% voltage drop would be enough to trigger the step down. Now it appears that the software tries to re-set to the higher charging level on its own. I've had the voltage problem for a while and my local hydro utility has just agreed that a new transformer is needed on the street to handle the car's charging load.
    charging Post.JPG
     
  4. ratsbew

    ratsbew Member

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    Wow. Will this become an issue in the not so distant future as more people own EVs?
     
  5. Cosmacelf

    Cosmacelf Active Member

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  6. Forty Creek

    Forty Creek Member

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    No doubt. One Tesla drawing 80 amps continuously adds more load than an average house. The transformer can only handle a fixed number of homes.
     
  7. mibaro2

    mibaro2 Member

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    I haven't got that 2nd update that you referenced, but am now looking forward to it. I have a public j1772 charger I use which constantly drops from 30a to 22a, and never goes back to 30a. Would be great if that 2nd update helps to fix this.
     
  8. David99

    David99 Active Member

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    It definitely will try to adjust up again, but it might drop down again as well. What might help is setting the charge current to 28 Amp for the start to avoid the drop altogether. It might still charge faster overall.
    In my case I tracked the charging session with VT. After the car dropped the load, it showed the voltage rise up over time (don't know why) and then the car eventually increased the charge current again. So I'm not sure if the car will just try to adjust up again from time to time or if it monitors the voltage and only adjusts up as it sees the voltage level increase.
     
  9. TexasEV

    TexasEV Active Member

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    It sounds like it's the public charging station that needs to be fixed, not the car.
     
  10. EriCal

    EriCal Member

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    What is "VT" that you used to capture your charging performance??
    We are having decreased charging rate problems on my Dear and Beloved Spouse's 85. I suspect the power source but can't pin it down. Your 'VT' would help.

    thanks, Eric
     
  11. David99

    David99 Active Member

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    VT = Visible Tesla. It's a software that communicates with your car and tracks all kinds of available data.
     

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