Kona EV "Winter Mode" - defined and condensed

Discussion in 'Hyundai Kona Electric' started by nzkiwi68, Jan 5, 2020.

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  1. nzkiwi68

    nzkiwi68 New Member

    I've been reading the manual, watching videos, reading posts and trying to properly understand the "Winter Mode" function for Kona EV that have the battery warmer fitted.

    I thought I'd layout what I now think it does. Please be kind to me if I've got it all wrong, because the manual description is pretty useless.

    1. You only get the "Winter Mode" on/off menu option if your Kona EV has the battery warmer fitted.
    2. The BMS will use the battery warmer to heat the battery whilst plugged into a charging connector, regardless of winter mode off or on, according to the battery temperature automatically. Manual page "H6".
    3. Winter Mode ON will heat the battery whilst driving if the battery gets very cold. I've read others say at under -10 deg C.

    So point 3 is really what 'Winter Mode" is all about, heating the battery whilst driving in very cold conditions for 2 reasons;
    • At very cold temperatures (under -15 Deg C) the BMS will drastically reduced the power output from the battery to a very low 35 kW. With Winter Mode ON, the battery warmer will prevent the battery from becoming too cold and thus continue to allow full power output from the car, at the expense of reduced range (because the 2 kW battery heater is used whilst driving)
    • Because the battery was heated during driving, fast DC charging is possible at higher rates immediately, because the battery has not allowed to get too cold. Without winter mode ON, the battery heater would come on when plugged in to charge, but obviously it will take time to heat up the battery and allow the faster DC charging rates. So winter mode ON helps faster DC charging rates, only useful at low temperatures and again at the expense of range as the battery warmer operates whilst driving.

    Therefore in Auckland NZ, with our comparatively mild climate (rarely under 0 Deg C, a few frost days per year) Winter Mode ON or OFF makes no difference, because it won't operate anyway.
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  3. You are likely correct on all points and already know more about it than many of us here. Where the 35 kW number come from?
    I left it on all last winter for lack of any better info. You can witness it's operation using Torque Pro, if required.
  4. Probably from this EV Puzzle Video starting @ 2:55

    Note : additional condition is below 20% SOC
    nzkiwi68 likes this.
  5. nzkiwi68

    nzkiwi68 New Member

    Yes, from that video
  6. nzkiwi68

    nzkiwi68 New Member

    Kind of annoying... all Hyundai need do in the manual is add a tiny bit more text, along the lines of:

    "Winter Mode is used when ambient conditions are below XXX Deg C and assists by keeping battery above yyyy Deg C whilst driving to assist with high speed DC charging and also to prevent the car from reducing output power from the high voltage battery. Winter mode in these colder conditions does reduce your range by approx aaa-bbb% but allows faster DC charging and full power output.

    Winter mode can be safely left on or off in milder climates as above XXX Deg C Winter Mode has no effect."
    navguy12 and ehatch like this.
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  8. Noting that he doesn't mention a source for that information. I take his videos with a medium-sized grain of salt since he's a bit prone to speculation.
    navguy12, SkookumPete and nzkiwi68 like this.
  9. papab

    papab Member

    It sounds like the battery warmer is an option? If you don't have the 'battery warmer', is there another system for cold weather thermal management for the battery?
  10. nzkiwi68

    nzkiwi68 New Member

    It's reported that even without the battery warmer, the system has the ability to scavenge heat from the electronics to help keep the battery warm. How well that works I don't really know. I can't imagine that it's going to work well enough in really cold sub 0 Deg C conditions.

    The reality is, if you live in a climate with below 0 Deg C temperatures, especially -10 Deg C and below, then it's my view that the battery warmer is essential equipment.

    The battery warmer in very cold conditions will keep the battery warm whilst plugged in and AC or DC whilst charging, so when you get in to drive, the battery will have a proper full charge. Without the battery warmer, the battery will struggle to get a full charge
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  12. KonaScot

    KonaScot Member

    My thinking was that the heat from the warmer in motion, while an energy expense, nets a greater increase in power available for range than would exist in a ambient temperature cold battery. No?
  13. Its an interesting thought but I have wonder when it actually does come on. I pretty much watch the battery care monitor most of time while driving. I have been driving with winter mode on with recent overnight lows in -25C range and day times highs around -15 to -18C and have yet to see the battery warmer come on while driving. A previous poster had indicated documentation that mentioned that it does not come on until -17C. I suspect that may be the actual battery temp not ambient. I have witnessed it come with the aid of torque pro while DC charging at -10C and I suspect it has also come on while the car was connected to shore power overnight.
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  14. nzkiwi68

    nzkiwi68 New Member

    What if the outside temperate was really cold, -20 Deg C and you needed to start and drive? Without the battery warmer the battery will be very cold and the power output will be severely limited, fast DC charging very slow and regen braking off. In these conditions a battery warmer is essential.

    If your garage is unheated and gets well below 0 Deg C, even when plugged in, without the battery heater, the battery will get cold.

    But, yes, you're right, the system does scavenge heat from the inverter and other electronic components to help warm the battery, but in severe conditions that won't be enough.
  15. KonaScot

    KonaScot Member

    Sorry, but I may not have been clear. I was talking about the electric battery warmer that the OP mentioned (on my 2020), being used while driving, and not any warmer to help with charging or while not in motion.

    My question is whether the stated 2kW energy cost of running the electric heater while driving recoups more in the way of range than it costs.
  16. I think if it did there would not be a switch. The tradeoff is performance over range.
    navguy12 likes this.
  17. KonaScot

    KonaScot Member

    I'd be good to know for certain....
  18. SkookumPete

    SkookumPete Well-Known Member

    I don't believe that range is affected significantly by battery temperature. Going back to the OP, the idea of running the heater while driving is to enable faster charging when you stop, and to prevent loss of power in very cold conditions.
  19. nzkiwi68

    nzkiwi68 New Member

    The manual states a albeit at a loss of range. Using the battery warmer whilst driving does reduce your range.
  20. herode10

    herode10 New Member

    Tired of getting frustrating charging rate on fast chargers (18-25 kW) under cold weather conditions, we got together a group of Kona owners to do some reverse engineering to understand when the battery heater activates. First thing to know, the BMS uses the temperature of lowest battery module in its logic to activate the battery heater. We found 3 conditions for the heater to activate:

    1. The battery heater will come On if the SOC is less than 33% and battery temp is -5 degC or less. It goes off when battery reaches 5 degC. This seems to be for conditionning the battery for an eventual stop to a fast DC charger. The Winter Mode needs to be active for this to happen.
    2. It will also be active when charging on 240v depending on battery temp as well. At -15 degC, it will engage around 82% soc. At 0 degC, it will engage around 91%. At 5 degC, activates around 93%. The Winter mode doesn't need to be active for this.
    3. The battery will be active on fast charger as well. In most conditions, it will heat the battery upto to 15 degC depending of the starting % SOC. The battery will continu heating due to the heat lost during charging.
    Good to know on fast chargers:
    Battery temp < 1 degC : max power 18 kW
    1 degC > Battery temp > 5 degC: max power 25 kW
    5 degC > Battery temp > 15 degC : max power 40 kW
    15 degC > Battery temp > 25 degC: max power 50 kW (50kW chargers) or 56 kW (>100kW chargers)
    Battery temp > 25 degC: max power > 70 kW (>100kW chargers)

    With battery temp as low as -20 degC, no heater activation was observed in other situations. It is believe that at much lower battery temp, the heater will activate to protect the battery. Minimum exterior temperature we had so far is about -25 degC.
  21. nzkiwi68

    nzkiwi68 New Member

    For point 3, DC fast charging, does the Winter Mode have to be on for the heater to operate?

    I would think not, but I'm interested to know from your findings.
  22. herode10

    herode10 New Member

    We forgot to test this. On my next DC charge, I am planning to validate this one. From an other forum I saw, a guy said it needs to be On. We assumed it was not required since it works without it on 240V charge.

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