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Full Charge Means No Regenerative Braking - 2016 Tesla Model X Long-Term Road Test

Edmunds.comEdmunds.com Posts: 10,059
edited July 2016 in Tesla
imageFull Charge Means No Regenerative Braking - 2016 Tesla Model X Long-Term Road Test

Turns out the regenerative braking system in our long-term 2016 Tesla Model X isn't always on. A full charge means there's basically no regen effect.

Read the full story here


Comments

  • kirkhilles1kirkhilles1 Posts: 860
    Interesting. I would think they would want the experience of braking to be the same no matter whether you had a full charge or near empty even if that meant discarding that electricity. Maybe discarding it is the problem...
  • Holy crap is that an oversight. You change the vehicle's coasting and braking performance based upon the amount of vehicle range - ? That's nuts.
  • texasestexases Posts: 8,829
    If the battery's full there's no place to put the regen electricity. And adding an extra device would cost $ and pounds.
  • thecardoc3thecardoc3 Posts: 4,995

    Holy crap is that an oversight. You change the vehicle's coasting and braking performance based upon the amount of vehicle range - ? That's nuts.


    No that's normal. Even the hybrids have to start relying solely on the mechanical brakes once the battery reaches a certain state of charge. Toyota hybrids use "B" mode on the shifter for mountain braking to create an engine braking condition to assist the mechanical brakes when the hybrid system regenerative braking has to shut down.


  • legacygtlegacygt Posts: 599
    On the list of drawbacks of electric powertrains I would say this is pretty low on the list but it's real. Having the state of charge contribute to a significant change n the way a car drives is annoying and potentially dangerous. Maybe they could add some dynamic aero to make up for the fact that there's no regen or engine breaking available.
  • yellowbalyellowbal Posts: 234
    This doesn't even seem like a hard problem to solve... dump the excess electricity to resistors and keep the brake feel the same.
  • texasestexases Posts: 8,829
    We're talking HUGE resistors. Why spend the $$ when all one has to do is press on the brake pedal?
  • lmbvettelmbvette South FloridaPosts: 93
    This surely is a design oversight.

    I have a Chevy Volt. Granted, the Volt is not a one-pedal driving experience, but it coasts like a normal car when in "D". However, if you put the vehicle in "L" it is 70% of what a one-pedal would be, and the brakes work the same. The brakes work the same whether I have a full charge, in Mountain Mode or zero charge running on gas regardless of "D" or "L".

    Don't worry about what other people think. Drive what makes you happy.
  • Holy crap is that an oversight. You change the vehicle's coasting and braking performance based upon the amount of vehicle range - ? That's nuts.


    No that's normal. Even the hybrids have to start relying solely on the mechanical brakes once the battery reaches a certain state of charge. Toyota hybrids use "B" mode on the shifter for mountain braking to create an engine braking condition to assist the mechanical brakes when the hybrid system regenerative braking has to shut down.


    OK, so when that condition is reached, does that engine braking profile cut in automatically or what?
  • yellowbalyellowbal Posts: 234
    edited July 2016
    texases said:

    We're talking HUGE resistors. Why spend the $$ when all one has to do is press on the brake pedal?

    Because the driving feel should not fluctuate when the battery is full or not. Plus the Model X is not an economy car.
  • 5vzfe5vzfe Posts: 161
    I'm sure other automakers employ something similar, but Honda's hybrid system avoids that scenario by diverting excess regenerative energy to the engine bay (in "B mode", after the batteries are full), where the electric motor creates friction by manually spinning the gasoline motor, and voila, engine braking. Again, not sure if other automakers have been doing this already, and it doesn't help the Tesla, but I thought that was a pretty clever solution to avoid braking inconsistencies.
  • kyolmlkyolml Posts: 37
    what? you charge the battery to full? it's going to degrade the battery every time 100% charge. Mostly just 90% charge per Tesla suggestion. Don't buy this X when edmunds done with it
  • gslippygslippy Posts: 514
    My former 12 Leaf did exactly the same thing - it's normal.
  • gslippygslippy Posts: 514
    lmbvette said:

    This surely is a design oversight.

    I have a Chevy Volt. Granted, the Volt is not a one-pedal driving experience, but it coasts like a normal car when in "D". However, if you put the vehicle in "L" it is 70% of what a one-pedal would be, and the brakes work the same. The brakes work the same whether I have a full charge, in Mountain Mode or zero charge running on gas regardless of "D" or "L".

    The Volt is different because the battery never completely drains or fills. "Empty" is something like 25%, and "Full" is something like 75%, so Chevy has the luxury of maintaining the same regenerative braking feel no matter what. Plus, keeping the battery in this narrow state of charge greatly extends its life.
  • thecardoc3thecardoc3 Posts: 4,995

    OK, so when that condition is reached, does that engine braking profile cut in automatically or what?

    No, the driver has to use the shift lever to go into "B" mode. http://www.toyotanation.com/forum/105-camry-hybrid/415634-b-mode.html

  • metalmaniametalmania Posts: 167
    Maybe they could just put some kind of warning light in the dash that the regenerative braking isn't in use until the battery drains to the appropriate level. I don't like the idea of the car's driving dynamics being variable like that, especially if there was a possibility of someone else driving the car that doesn't do it every day.
  • gslippygslippy Posts: 514

    Maybe they could just put some kind of warning light in the dash that the regenerative braking isn't in use until the battery drains to the appropriate level. I don't like the idea of the car's driving dynamics being variable like that, especially if there was a possibility of someone else driving the car that doesn't do it every day.

    The difference is noticeable, but not alarming. The variable is how hard you push the brake pedal, that's all. With regen not helping, an EV stops just like any other car.
    And, it should be noted that regen is restored very soon after starting a journey with a full battery, because the battery's depletion means it now has room for that regen energy to go.
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