[Bill N]

Apologies in advance for basically reposting this particular question from another thread that I started, but I’d really appreciate any advice on this as I’m unfortunately unable to use the ODB port in my car to easily work any of this out for myself!

I’m hoping there may be some experienced Kona (or eNiro / Soul EV) drivers here (probably with ODB devices) who are able to say how long is typically required for the battery heater to heat the pack to 25°C, under a range of example conditions.

Earlier today I was trying out 100kW+ DC charging for the first time after arriving at 41% (too high to be ideal, I know, but the consumption was a lot less than ABRP predicted), and it didn’t manage to get over 56kW before the standard ramp down point around 57% - I take this to mean the battery hadn’t completely reached 25°C in the relatively short amount of time since plugging in (the ambient temp was 1°C).

So, for example - if the ambient temp is approx. 1°C, and charging is initially at 40kW (indicating the battery is somewhere between 5-15°C when plugging in), then how long might it typically take for the battery to reach 25°C, and hence for the max charge rate to kick in?

I suppose what I’m really trying to work out is, at different ambient temperatures, how low does the charger arrival SoC need to be to make it worth going to/occupying/paying for an ultra rapid charger?

In an instance such as my session today, I may as well have used a 50kW charger given the very small time saving from charging at 56kW for just several minutes.

How low would the arrival SoC needed to have been today in order for the max charge rate be achieved for a worthwhile amount of time? What about if the ambient temp was 5°C or 10°C?

(All of the above is on the basis of the car being driven 'normally' for at least 100 miles and with with no attempt to heat the battery by driving in an unusual manner).

 

[KiwiME]

I looked at my graphs and the battery heater manages a rise of about 5°C in 10 minutes. There was a 2 minute delay after start of charging before the heater actually kicked in.
If you listen carefully you can hear the coolant gurgling when the pump starts.

But, the heater stopped once it reached 15°C. It might matter that it was a 50kW charger which is all I have access to.

If you were relying on battery losses alone to warm the pack, take about 2% of the prevailing charging power as losses and factor that with the 5 minutes per 2 kW from the battery heater to get an idea of the time.

There is a long thread on a German Kona site but the automatic translation is sometimes painful to read. I try not to post there much because I can't respond in German and don't want to annoy them. The gist is this (from Gearsen):

In short:
Battery will be heated while charging when below 15 ° C
Battery will be cooled while charging when over 35 ° C
Battery wellness temperature and highest charge and discharge rates between 25 ° C and 35 ° C

The thought is that losses only provides heat from 15°C up.

 

[Bill N]

Thanks again @KiwiME for your input. I think that post from 'Gearsen' that you mention is (or is similar to) this post from him on 'going electric'. But I noticed someone else then states the battery heater stops at 20°C, not 15.

In any event, useful to know that it takes about 10 mins to rise 5°C - so if I guess that the battery was, say, 10°C when I plugged in then it might take at least 20+minutes to reach 20°C, and then some additional time to hopefully reach 25 just via the charging losses and residual warmth from the heater.

I suppose I could fudge a test for myself even without an ODB reader by just arriving at a charger at different ambient temperatures with, say, 10% and then timing how long it takes for the max power to kick in. I’d then know that at a given ambient temperature it probably isn’t going to be worth using an ultra rapid if the arrival SoC is above x%.

I guess I’m just sort of hoping someone has already figured all this out for me so I can be lazy!

 

[Steven4]

There are actually 3 coldgate levels:

Reaching and maintaining 25°C in battery pack in winter (here at 2°C) is possible only on higways (85+ mph) in E-Niro with heat pump:

 

[Bill N]

Thanks @Steven4 - this seems to confirm what I’ve found on another forum

I tested charging again in my car this morning:

• left home with cold battery (no charging overnight and ambient temp about 1°C)
• drove 65 miles to the ultra rapid charger including 40 miles or so at 70 and a bit mph.
• arrived at 15%
• charging started at 38kW then 42kW after a minute

• cabin heating turned on
• about 2m30s after plugging a noise started (presumably the battery heater kicking in)
• 12m after plugging in and at 25%, charging increased to 56kW, then 54kW

• stayed like this for the next 12 minutes, and then I decided to turn cabin heating off (thinking that perhaps the cabin heating is 'stealing' some of the heat that could otherwise be helping the battery reach 25°C)
• about 6 minutes later (so about 30 minutes after plugging in) and at 50%, charging increased to 77kW
• stayed at 77kW for only 1 minute then reduced to 71kW for another 2 minutes

- then charging reduced to 57kW again at 54% (a little earlier than expected).

Thoughts/conclusions:
1. Not sure if turning cabin heating off made any difference or not.
2. Arriving at an ultra rapid charger with 15% after leaving home with a cold half empty battery and driving normally in the UK only gives a few minutes of maximum charge rate in 0-2°C weather.

 

[Bill N]

This video is useful. Basically, it's only going to potentially be an issue if the ambient temperature is close to zero. If it's nearer to 5 degrees (more typical for an average 'cold' winter's day in the UK) then it seems the car is able to keep the battery at or near to 25 degrees between ultra rapid chargers. (The first charge of the day will still be a little slower due to having to begin at 56kW for 15-20 mins.)

 

[KiwiME]

But I noticed someone else then states the battery heater stops at 20°C, not 15.

Here's proof that mine stopped at 15°C. The heater temp spikes before the coolant flow starts and then stays high for some time after it stops for fairly obvious reasons. The continued increases in pack temps after the heater switches off is likely due to temperature equalisation throughout the mass, in addition to acquiring the approx 1 kW heating due to battery losses.

 

[Bill N]

a was

Here's proof that mine stopped at 15°C. The heater temp spikes before the coolant flow starts and then stays high for some time after it stops for fairly obvious reasons. The continued increases in pack temps after the heater switches off is likely due to temperature equalisation throughout the mass, in addition to acquiring the approx 1 kW heating due to battery losses.

View attachment 140009

Thanks - yes, after some more reading it definitely seems like the suggestion of 20% by that one person was an outlier.

 

[eurokeitai]

Given the 3 conditions where battery heater turns on, no wonder charging is slow and "battery care" is almost never observed . Take a normal long trip
1. You leave at home at SoC 100%, because you are going to need all the juice. Given the battery heating rule #2, your battery has been warmed past +5c. Depending on how cold it is and how long ago before leaving home 100% was reached, the battery cools back into less than +5c.
2. You drive 300km, and because Kona is efficient, the battery doesn't warm up by just driving. Eventually the Battery SoC drops below 33%. But the rule #1 doesn't trigger, because your battery is warmer than -5c!
3. You arrive to the charger, with a battery at less than +4c, and get the whole whopping 25kW charging speed until the batttery warms up.

The "battery need to be < -5c" rule should be updated to "whenever battery is < +5c" so we get at least 40kW when arriving to charger.