Erroneous message that battery is fully charged in cold weather?

Discussion in 'Hyundai Kona Electric' started by Mattsburgh, Dec 6, 2019.

  1. Mattsburgh

    Mattsburgh Active Member

    I have noticed that since it got colder, there have been quite a few times where my SOC is at 96-98% and yet I will get the message that regenerative braking is not available b/c the battery is fully charged... when obviously that is definitely not the case.

    Anyone else experiencing this? I only saw in warm weather once and when I did, it was actually true, the battery was at 100%.
  2. hobbit

    hobbit Active Member

    Slamming a lot of current into a cold battery isn't a particularly
    good idea in general, especially when it risks pushing cell voltage
    above 4.2, so the car is trying to help both you and itself.

  3. I do notice that charging jumps from 98% to 100% after only 5 addition minutes charging at 1.6kW. The normal increase at that rate is 2% SoC per hour.
  4. Yup, all the time for the past couple of (cold) weeks. Sometimes the warning comes up after I have been driving for quite a while and there's clearly lots of headspace available in the battery. Also, the message will come up even while the Regen "counter" on the speedometer is counting up the regen distances being generated. Sometimes when the message comes up I cannot use the paddle to slow or stop but other times the paddle works fine even as the message is being displayed.
  5. Mattsburgh

    Mattsburgh Active Member

    Yeah it's done it even after I've driven 10 miles, which is why it seemed to me pretty clear that as you said there should be lots of headspace available. One time it happened I looked and SOC was only 96% and a couple other times it was 97%. It did it tonight in fact even though according to the charge info it would take 2 hours 55 minutes on level 1 to fully charge.
  6. Mattsburgh

    Mattsburgh Active Member

    I like this answer so I'm going to assume that's why it does it. :) Plus, mostly I wanted to verify there isn't something "wrong" with my regen, but sounds like others have noticed similar behavior.
  7. I've noticed a couple of different situations: when I am fully charged and try to use the Regen paddle, shortly after starting out, the "can't Regen, battery is fully charged" message will come up (along with a chime) and the paddle will have ZERO effect. I need to use the brakes to stop.

    Next day, same situation, I pull the paddle, chime and message appears, but the paddle WORKS, Regen metre shows it's making power and the car slows and stops using only the paddle.

    Also, I will get this same behaviour after driving for 15 minutes (battery clearly can't be full anymore)

    Sometimes I wonder if the car actually means "battery is too cold" but they just didn't create a proper message for the display.
    Mattsburgh likes this.
  8. I think what hobbit mentioned is the culprit. When you regen it can be as much as a 150+ Kw/h hit . Depending on the temperature the BMS is making the executive decision to decline the fairly large incoming charge even if there is small battery headroom available.
  9. hobbit

    hobbit Active Member

    I know this at an intuitive level from watching the Prius, where slowing on a
    cold day only regens at like 30 - 40 amps on a pack that can take up to
    100, and the hydraulics come in to help. As I drive more and the pack
    warms up, the limit gradually increases. Most Prius drivers can't tell the
    difference since there's no instrumentation to show this. But it's pretty
    standard [and important] BMS behavior at this point.

  10. ehatch

    ehatch Active Member

    Are you guys using winter mode when this happens?I haven't seen the regen.unavailable/fully charged alert.Just that snow flake to warn of potential ice. I don't charge to 100% unless it's for a road trip,or I have a lack of charging once on the road. 90% at most.
    electriceddy likes this.
  11. I always start off at 100%. And it's cold in Ontario. Winter Mode is on.
    Mattsburgh likes this.
  12. Mattsburgh

    Mattsburgh Active Member

    I'm not sure we have winter mode in the U.S. ... hmm. I will check.

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