Fast charging the Kona

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Ev050

Ev050

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Hello forum,

I tried for the first time the Electrify America fast chargers network, and I was disappointed about how low the maximum charging rate was(28.8 kW/min) Although I still got charged at a rate of 1-150kW. Talked to them to understand the reason of that rate and basically told me was the car fault. That’s after the initial communication with and DC fast charger and the onboard charger, the needed kW was set to 80 kW but then the safe rate of charging was set at 28 kW/m??? So this means I cannot charge to more than 28.8kW/m? I have seen videos where the Kona is charged the at a 50kW/h in a 150kW charger like the one I used. Can anyone help me understand this? Should I get my battery checked? Have the 2019 ultimate btw.
Thank you in advance

Lou


Sent from my iPhone using Inside EVs
 
I have seen this complaint on forums where the Konas and Niro won't accept the 57 kWh/hr the manual implies it should (80% SOC in 54 minutes for the Niro). I noticed the charge management menu when flipping through the various settings. I have a Niro, but perhaps Kona uses the same software. Go to the charge management screen and play with your charging current settings for DC charging. I bet you are not set to maximum.

Note that frequent fast charging will quickly reduce your battery capacity. My plan is to only use fast charging when I must, like if I am on a long road trip and do not want to stop for several hours at a time.

Screen Shot 2019-12-16 At 10.07.32 PM

Screen Shot 2019-12-16 At 10.07.32 PM

the charge management menu
 

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Yeah that happens with the Kona and Niro. It's a) a rip off to charge at EA due to the price, b) batteries don't like the cold, and c) batteries don't like fast charging at higher %.

I'm not going to mention the user settings DavidT already covered. He did a good job on that.

How cold was it when you charged? Where you driving the car for a while before level 3 charging? Basically what I'm getting at is, was the battery warmed up before level 3 charging?


Cold temperature limits the kW speed the car battery can accept. 20-30 degrees F isn't enough for the battery warming to kick on to help warm it up. Being above 40-50F or driving for a while are the two ways of warming up the battery and being below 40% battery is the ways to get the car to accept the full 74-76ish kW charging speed.


Another thing to elaborate on with the below 40% battery. There is a battery charging curve. The charging speed from 0-40% is 74-76ish kW. From 40-55% it's around 60ish kW. From 55-70% it's around 55kW. From 70-75% ramps down again to 30ish kW. From 80-100% it curves down to from 25kW to 1.4 kW.


All of this is found in the graph on https://ev-database.org/car/1204/Hyundai-Kona-Electric-64-kWh. It's the same graph for the Kona and the Niro. Basically, the car battery is protecting itself from fast charging. At higher SoC, there is higher voltage, making it harder for the battery chemistry to accept more charge. An analogy is manually pumping a bike tire pump. The higher pressure the tire is, the harder it is to press down on the pump. The higher the battery charge, the harder it is to accept more charge.
 
niro525 said:
Yeah that happens with the Kona and Niro. It's a) a rip off to charge at EA due to the price, b) batteries don't like the cold, and c) batteries don't like fast charging at higher %.

I'm not going to mention the user settings DavidT already covered. He did a good job on that.

How cold was it when you charged? Where you driving the car for a while before level 3 charging? Basically what I'm getting at is, was the battery warmed up before level 3 charging?


Cold temperature limits the kW speed the car battery can accept. 20-30 degrees F isn't enough for the battery warming to kick on to help warm it up. Being above 40-50F or driving for a while are the two ways of warming up the battery and being below 40% battery is the ways to get the car to accept the full 74-76ish kW charging speed.


Another thing to elaborate on with the below 40% battery. There is a battery charging curve. The charging speed from 0-40% is 74-76ish kW. From 40-55% it's around 60ish kW. From 55-70% it's around 55kW. From 70-75% ramps down again to 30ish kW. From 80-100% it curves down to from 25kW to 1.4 kW.


All of this is found in the graph on https://ev-database.org/car/1204/Hyundai-Kona-Electric-64-kWh. It's the same graph for the Kona and the Niro. Basically, the car battery is protecting itself from fast charging. At higher SoC, there is higher voltage, making it harder for the battery chemistry to accept more charge. An analogy is manually pumping a bike tire pump. The higher pressure the tire is, the harder it is to press down on the pump. The higher the battery charge, the harder it is to accept more charge.
Click to expand...

Thank you for your reply! Regarding the temperature, it was in the low 30’s that day and I did drive the car for at least 10 min before charging. I will look into the settings but I think I set it up to 90% for fast charge. Maybe I should just go to 70% unless I am planning a road trip. Thanks for the links and advice! I need to learn more about my EV otherwise how am I suppose to convince others than EV’s are superior!


Sent from my iPhone using Inside EVs
 
David T in Silicon Valley said:
I have seen this complaint on forums where the Konas and Niro won't accept the 57 kWh/hr the manual implies it should (80% SOC in 54 minutes for the Niro). I noticed the charge management menu when flipping through the various settings. I have a Niro, but perhaps Kona uses the same software. Go to the charge management screen and play with your charging current settings for DC charging. I bet you are not set to maximum.

Note that frequent fast charging will quickly reduce your battery capacity. My plan is to only use fast charging when I must, like if I am on a long road trip and do not want to stop for several hours at a time.

Screen Shot 2019-12-16 At 10.07.32 PM

Screen Shot 2019-12-16 At 10.07.32 PM

the charge management menu
Click to expand...

Hi David!
Thank you for the advice, I believe the charge management is set at 90% for fast charge, but maybe I should lower it to 70 or 80% and see if that helps? It was a cold day so probably that had something to do with it, but I am guessing that battery wasn’t cold since I was driving line for 10 min prior to start charging. Although I did have some issues with the app and had to call costumer service(seems to be a common thing).
Thank you again!


Sent from my iPhone using Inside EVs
 
David T in Silicon Valley said:
Note that frequent fast charging will quickly reduce your battery capacity.
Click to expand...

I think this overstates the danger. What I have been reading is that the major thing that will reduce the battery capacity is overheating. And DCFC does raise the pack temperature, so DCFC together with high ambient temperatures are going to be the worst case. That being said, the car should limit the charge rates when the battery temperature is high in an attempt to prevent further increases in the temperature.

Some of the concerns related to DCFC seems to come from experiences with the Nissan Leaf, which has air-cooled batteries, and cannot do as good of a job with temperature management. This becomes a problem on long road trips where you need to make multiple DCFC stops in a single day. Every other EV out there has liquid cooling (circulating glycol with a small radiator), which does a much better job of temperature management.

There was a recent article that discussed battery health:

http://www.insideevsforum.com/community/index.php?threads/8-lessons-about-battery-health.7811/

In the winter excessive temperature is going to be less of a concern - the temperatures may in fact be too low to support the highest charge rates. So in the winter the optimum strategy is probably to use DCFC after having driven a bit to raise the battery temperature.

In the summer the opposite is true. The optimum strategy would be to use DCFC 1st thing in the morning (if possible) when the ambient temperature (and the battery temperature) is the lowest.
 
Ev050 said:
Hi David!
Thank you for the advice, I believe the charge management is set at 90% for fast charge, but maybe I should lower it to 70 or 80% and see if that helps?
Click to expand...

There is a setting for charging current that is separate from the maximum percentage charge. That is the setting highlighted in my screenshot in the left column.This setting limits how quickly your battery is permitted to charge and should have the ability to increase or decrease the charging rate in kWh/hr. The maximum percentage charge will only limit how far your battery charges up, not the rate.
Screen Shot 2019-12-16 At 10.07.32 PM

Screen Shot 2019-12-16 At 10.07.32 PM

the charge management menu
 
I think a couple things are not quite correctly mentioned here:

- The mentioned charge speed settings ONLY apply to AC charging not DC charging as you can see in the screenshot.
- yes, excessive temperature and charging are not necessarily good for the battery. However, that's why our batteries are liquid cooled! So it shouldn't be as big of a danger as it might be implied above.
- driving for 10 minutes will not warm up the battery enough to get the maximum charge rate (assuming it is cold outside and the car has been sitting in the cold). Things are of course different if you're parked in a garage etc.
 
My only concern about DCFC is that the Kona owners manual warns about avoiding this if practical in two places at least, giving no further explanation or advice. Oddly it never mentions avoiding sitting at 100% if practical even though all generic Li-ion references warn about avoiding that part of the envelope to enhance life.
The pack is rated at 180 Ah so you can work out that 70 kW is about "1C" charging at 4.0V per cell, so 47 kW is really not that high.
 
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