Weird/dangerous ACC/regen braking behavior

Discussion in 'Hyundai Kona Electric' started by victor_2019, Aug 17, 2019.

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  1. victor_2019

    victor_2019 Active Member

    I just experienced something weird and dangerous.

    Radar cruise control was on and i was getting of the highway and traffic was slowing down to a light. I was in eco mode with level 3 regen selected. Battery was at 30% charge.

    The car started to decelerate and then suddenly the regen went away and car was coasting.

    I had to slam on the brake to stop and while i was braking the car was still coasting, no regen and braking was with mechanical brakes. The power display was not showing any regen.

    And the braking was not very strong. The force i felt was lower than the force I feel from level 3 regen.

    No error message was shown l, blue link diagnostic showed no problems.

    The regen came back after i left from the stop light, without me doing anything special.

    Anyone else experience something similar?

    It's the first time it happens to me
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  3. sosmerc

    sosmerc New Member

    Strange behavior indeed....especially since no error message occurred. The only strange behavior I have experience with my Volt was when something must have suddenly blocked the Active Cruise Control Radar sensor....but I DID get an error message and "normal" behavior returned a few minutes later.
  4. You did of course check the brake fluid level?
    robxb likes this.
  5. Your breaking with the friction brakes was less than Regen 3 braking? How did you come to a stop then?

    Sent from my moto x4 using Tapatalk
  6. CJC

    CJC Well-Known Member

    There are no reports of anything similar on all the Kona EV forums I read. I suspect some sort of driver error that we all make on occasion. I would think if your Smart Recuperation/Auto Gen was set to a level it would not have failed without an error showing in the diagnostics. It is a wake up call for all of to not become too reliant on the wonderful technology available to us. My husband uses ACC all the time and I worry that he will forget about using his own brain such as it is lol.
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  8. victor_2019

    victor_2019 Active Member

    The car is brand new.
    No i didn't check fluids in the past month but why would that make the regen braking disappear?
    robxb likes this.
  9. victor_2019

    victor_2019 Active Member

    Why wouldn't i come to a stop? Regen level 3 is pretty strong. It's stronger than my normal driving braking.
  10. CJC

    CJC Well-Known Member

    Did you actually pull the right paddle?
  11. victor_2019

    victor_2019 Active Member

    I don't use the smart regen option, eco is set to regen 3, normal mode to regen 2 and sport to regen 1.

    That stop was in a curve and it's possible that the radar stopped seeing the car in front and wanted to accelerate. But that doesn't explain the lack of regen when i pressed the brakes?

    I tried some braking later and moderately pressing on the brake pedal will show almost full regen (4 bars or more) and i get a good decel level.
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  13. CJC

    CJC Well-Known Member

    Yes I read somewhere in the owner's manual about hills and curves affecting the radar, and we have experienced that twice. I'm not sure what you mean about lack of regen when you press the brakes? I always use Smart Recuperation and I can make all regen disappear with the right paddle. Then I use the left paddle to get back the regen level that I desire.
  14. I honestly don't know if low brake fluid would have any affect on regen, but I was trying to address the weak braking you reported.
    One of my Leafs had an issue with master cylinder that required a TSB to resolve similar type complaint.
    I would venture to guess this would be the first thing a Hyundai service tech would check for.
    With the multitude of software on this car who knows how one system failure (or software freeze) could affect another.
  15. ACC is not designed to detect a stopped object in front of the car. As you described it was in a curve, so the ACC and possibly the front collision avoidance system didn't detect the traffic in front of you until the last second and didn't activate.

    The only weird thing is that you report the normal brakes didn't work right which is weird. I'm still not sure how you were able to come to a stop at all if your brakes didn't work right!?

    Sent from my moto x4 using Tapatalk
    Last edited: Aug 17, 2019
    electriceddy likes this.
  16. I don't understand your situation. You said Regen didn't work and your brakes didn't work. Now you're saying Regen 3 got you to a stop? If your Regen 3 is stronger than your brakes, then your brakes definitely need a check! Or you have a very light foot. The brakes need to be able to bring you to a stop in no time. Actually they need to be so strong that they stop the tires. Only ABS will then release the brakes to stop then from skidding.

    So have your brakes checked if that is not the case! Immediately!

    Sent from my moto x4 using Tapatalk
    electriceddy likes this.
  17. ^^^ I second that
    XtsKonaTrooper likes this.
  18. FloridaSun

    FloridaSun Well-Known Member

    I firmly believe that there is a software bug in the regen settings. I had my regen change level without me changing it, even during a trip. Mine didn't turn off but dropped down a level.
    ehatch likes this.
  19. Please be sure to report these issues to Hyundai as without reports nothing will ever get done to fix.
    ehatch and FloridaSun like this.
  20. FloridaSun

    FloridaSun Well-Known Member

    Will report it.
    ehatch and electriceddy like this.
  21. ehatch

    ehatch Active Member

    isn't a car an "object?" My ACC stops from hitting another vehicle in grid lock. I am still unsure about pedestrians. It definitely doesn't sense cyclists with the blind spot detection whereas the Bolt EV does.
  22. ehatch

    ehatch Active Member

    I feel the quite unpredictable now that I've driven over 2 months. Some days regen.3 ,my permanent setting will bring me to a stop.Under the same speed, conditions,it will not. Where even the left paddle does literally nothing,forcing me to use the mechanical brakes.

    The ACC has actually continued to drive forward/creep even though it has detected another vehicle stopped in front of me,and had already stopped. Frankly, I thought I was pressing the accelerator,but during the same drive,I paid more attention,and it wasn't a twitchy right foot :rolleyes:

    My concern for complaints like the ones in this thread surrounding ACC,and regen. Hyundai will want its dealers to "duplicate"the issues.Mine are intermittent,and I highly doubt the dealership's going to let their EV tech.hang out with us indefinitely to duplicate. Even IF the issue reproduced.Are Hyundai's EV techs.experienced enough to "feel" the difference given how few Kona electrics get sold? My Bluelink health report shows everything's fine.
    Last edited: Aug 18, 2019
  23. I had a play around with this today. I could not get SCC to do anything wrong other than the usual sudden braking due to parked cars on the outside of a corner.
    I can only guess that once the radar lost the car ahead the SCC accelerated back to the set point at the rate determined by the SCC response setting: slow, normal or fast. ("Slow" could be misinterpreted as coasting, perhaps?) Whenever I hit the brake pedal SCC dropped off immediately and I was back to whatever fixed regen level was set and the brakes worked fine on top of that.
    I can only suggest that if it happens again, take the car in to the dealer because it certainly doesn't sound normal and perhaps an error has been logged.

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