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Regen Braking Not Working

Discussion in 'Model S: Driving Dynamics' started by TexasTech44, Jul 7, 2017.

  1. TexasTech44

    TexasTech44 Member

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    I charged my battery to 100% for a road trip, and randomly my regen braking stopped working for an hour or two. When I'd let off the gas, it would coast like an ICE car, and no brake lights would come on. Has anyone else experienced this?
     
  2. gabeincal

    gabeincal Enjoying Napa life the electric way

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    So when you charge to >98% you ccan expect lower or total lack of regen and it will be visible in the energy app on your dash gauge via dotted lines! Having said that you mentioned 1-2 hours which, if driven for that long would mean that you're way below that SoC and would seem abnormal to me!
     
  3. sdorn

    sdorn Director of Awesome

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    Right, you only lose regen until it gets down to 95% or so.
     
  4. jerry33

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

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    Totally normal. There's no room left in the battery to take additional charging.
     
  5. Skotty

    Skotty 2014 Model S P85

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    Haven't heard of anyone having problems with this. It's normal to lose regen in the 95-100% battery range. Also check the setting for regen to see if someone turned it to the low setting. It may also get reduced if the battery is too hot or too cold, but I don't know specifics on that. Beyond that, if regen doesn't seem to be working, take it in for service.
     
    • Like x 1
  6. daniel

    daniel Active Member

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    The first time it happened to me on my Roadster I thought "What's wrong???" Then I noticed a "Regen" icon on the dash, and I figured, "Okay. Something's wrong but the car knows something's wrong." Turns out, as mentioned above, if the battery is too full to accept charge, it won't do regen, and there's an icon to let you know.

    Then it happened again when I had not charged to full, and I went though the same thought process as above. Turns out that if the battery is too hot it won't accept regen either (and as above, it shows the icon.) This was a very hot day. I had driven a fair ways and then parked in the sun for a couple of hours. Car worked fine in spite of the heat, but it put up the regen icon and would not accept regen. So it felt like driving a car without regen, which feels really weird when you're used to regen.

    Nothing was wrong either time. Car was back to normal when the battery went down a bit, in the first case, and was fine after it had cooled off in the second case.

    Love my Tesla. So much fun to drive!
     
    • Like x 1
  7. scottm

    scottm Active Member

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    In hindsight, did you need to charge to 100% do you think?

    If you only go to 90% you'll always have regen as you'd expect when you drive away.

    (Put your car model in your signature profile so we can see what you're talking about.)
     
  8. Tam

    Tam Active Member

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    Some people refuse to read owner's manual because they think it's just a legal disclaimer but please don't ignore its vast information:

    In the section "Instrument Panel - Driving" that has pictorial illustration:

    "6. On the Energy graph, dashed lines appear on the power meter if Model S is limiting power. The dashed lines appear on the top portion (energy being used) when power available for acceleration is being limited, and on the bottom portion (energy being gained) when power that can be gained by regenerative braking is limited.

    Model S limits power for many reasons. Here are just a few examples:

    • Acceleration may be limited when the Battery is reaching a low state of charge or if the powertrain is hot.
    • Both acceleration and regenerative braking may be limited when the ambient temperature is either very high or very low.
    • Regenerative braking may be limited when the Battery is fully charged."

    So if you have a habit of displaying your Energy Consumption Graph on your dashboard, you would see yellow dashed line at its bottom scale indicating reduce regenerativie braking and you could diagnose by the process of elimintation:

    Is the power train too hot?
    Is the weather too hot or too cold?
    Is the battery charged up more than 90%?

    So, in this case, you would realize those dashed yellow lines are there because you charged your battery fully.
     
    • Informative x 1
  9. gavine

    gavine Petrol Head turned EV Enthusiast

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    Chevy Bolt has a "hilltop mode" which limits charging to 90% so that you'll have regen available the next morning on your way downhill. AFAIK, that's the only way to limit charging on the Bolt below 100%. All EV's should have a slider like Tesla with the 90% max daily charge and you need to "force" it to 100% when needed.
     
  10. AmpedRealtor

    AmpedRealtor Well-Known Member

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    Regen is always limited when you charge to 100% - there is nowhere for the regenerated energy to be stored when the battery is full.
     
  11. AWDtsla

    AWDtsla Active Member

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    Nah, It came out of the pack, it can go back in. Depends on your pack chemistry and temperature. The silicone anode cells are terrible for this, they have to be at nearly 50C for there to significant regen at 100%.
     
  12. AmpedRealtor

    AmpedRealtor Well-Known Member

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    You know better than this. Regen is always limited when the pack is full. Makes no difference about the pack type.
     
  13. AWDtsla

    AWDtsla Active Member

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    Oh it totally does. 85's do better than 90's. And as above, 90's need to HOT. Try a hot day with range mode on (for higher pack temp) and a 100% supercharge.

    edit - (and arrive at the supercharger with an already warm pack)
     
  14. TexasTech44

    TexasTech44 Member

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    Thanks for your answers. It was definitely due to the battery being full. Lesson learned.
     
  15. AmpedRealtor

    AmpedRealtor Well-Known Member

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  16. smilepak

    smilepak Active Member

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    I don't think regen work well when battery charge above 95%, especially at 100%. There is no room for charging. The less battery you have, the better it work.
     
  17. dgpcolorado

    dgpcolorado high altitude member

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    As several have pointed out above, regen is also limited when the battery is cold, as you may find out if you park in a cold place next winter. IME, it seems to start with a battery temperature that is less than about 10ºC (50ºF) and regen drops sharply the colder the battery is. Having a high state of charge and a cold battery reduces regen even more. Charging speed is also slowed with a cold battery (until it warms up).

    Just be aware of this. One workaround for a cold battery is to schedule charging to finish at about the same time one plans to leave, since charging warms the battery. FWIW.
     
  18. gavine

    gavine Petrol Head turned EV Enthusiast

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    This!!!
     
  19. AmpedRealtor

    AmpedRealtor Well-Known Member

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    Too bad the mobile app doesn't allow you to enter a destination time and let it figure it out on its own. Tesla should automate some of this stuff for us.
     
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