Charging Amount is Consistently Dropping Over Last 3.25 Years

My three year old 2020 model is still averaging 320-340 miles at full charge, well ahead of the EPA range. Living in Hawaii, winter cold is not an issue, of course.

 

I should have mentioned that my car is very low mileage for its age -- about 13,500 -- so battery degradation isn't an issue. Strikingly, when I moved to my current location my range took a leap upward. I'm in the hills about 7 miles out of town, so my typical shopping/errands run starts with about 6 miles of fairly gradual downhill, which seems to hit a sweet spot in terms of regen vs. consumption.

 

This conversation is getting us to the measurement of the vehicle's battery pack State of Health rather than using the vehicle's (unknown?) algorithm which is affected by way too many variables. Any updates on recommended OBDII hardware and/or bluetooth apps which readily show the pack SoH and individual cell voltages and the usual parameters of interest as well as perhaps calculated driving efficiency with graphs? Prefer iOS, but have an old Android tablet and OBDLinkLX if needbe, but willing to splurge on our 'new' Kona Electric (named 'Konik').

 

I haven't seen any significant change in GOM since I bought the Kona in 2018. It was 515 km (322 m) when new and it's stayed between 496 (winter) to 510 (summer). The replaced battery pack in Oct 2022 didn't change anything. My local climate is essentially identical to yours (adjusted for opposite hemispheres in the image), just slightly narrower in span. However ... local speed limits are low, 50 to 80 km/h (30-50 mph) with light traffic. I just drive normally but rarely use (heat-pump) heating or AC. There are no higher-speed roads local to me and that is one important difference. After my most common daily trips the dash reads under 12 kWh/100km (5.2 mi/kWh) which is very good economy. My tires are set to 40 psi. I also don't drive much and only have 26,000 km on it, not that it should affect the comparison.

The normal max cell voltage is 4.16 and I don't think an aged cell would go higher, or lower than the minimum of 3.16 V despite that I suspect some might believe it dynamically adjusts to compensate for natural loss of capacity.

Aside from reading the current SoH value, to properly assess the battery you need to document the pack's 'odometers' CCC, CDC, CEC and CED at both extremes of SoC, as I've posted about several times. One reading at 95-100% (incl displayed SoC preferably to half a percent from OBD) and another set of the same parameters under 15%. It doesn't matter how you drive in between those readings, or how long it takes.

A couple of owners have reported (on FB) reading under 95% SoH but I noted that both live in fairly hot areas, inland SoCal and Phoenix.


(https://weatherspark.com)

 

I have a 2019 and used to be seeing 285-310miles on 100% charge. now I only see 265mi on 100%. I initially thought its related to the battery recall because my ranged dropped about 10% after battery swap but now I'm getting close to 265mi range and about 220mi real world driving range...

 

There are a lot of variables out there.....Did you get new/different tires, change tire air pressure, different driver or driving habits..and so on? My 2019 still shows about 400 miles @ 100% (based on the previous driving conditions, back country roads and no highway speeds, on the interstate after a 70 mph run for an hour or more, 80% shows about 220 miles, LOTS OF VARIABLES!

 

My 2019 Kona EV is currently at 64,000 miles. I live in SoCal. I only charge my battery to 90%. At 90%, I still get between 287 and 318 miles depending on the outside temperature. In the winter, I get 287 miles at 90%. In the summer (which is at the time I am typing this), I still get 316 to 318 as the day I bought the car. The car is still on the original battery. Hyundai keeps contacting me to change the battery. I want to wait another year until I get around 75,000 to 80,000 miles before making the jump for a new free battery. I hate to see a good working battery going into scrap. The car has 100,000 miles or 8 years of warranty on the battery as I spoke to them on the phone. I have a blue tooth OBDII where I can monitor the voltage of every single cell from my phone. The battery has 98 cells. If I detect any anomalies in the voltage readings, I will have Hyundai change the battery for me right away. Until then, I will keep pushing it as far as I can.

 

Two things to think about:

• Hyundai want to swap out your battery because a number of units in Korea have spontaneously ignited. I hope that you are not parking your unit indoors!
• Your Kona like mine (2019 model year) has a lifetime warranty on the battery, so you don't have to worry about changing it out too soon.

 

My old battery was in perfect shape as well but I had to accept that I couldn't drag it out forever and was one of the last in this country to have this done Oct '22. The defect present doesn't affect the battery energy capacity as long as it doesn't fail. My new battery had been waiting in stock, unlike in other parts of the world and was already 10 months old according to the manufacturing tag.

The battery of course really has 296 cells. Each of the 98 "cell" voltages is the combined total of three cells in parallel - with a voltage resolution in 0.02 V increments. One rogue cell would have to "fight" the other two good cells enough to force the combined reading out of the normal range (0.00 to 0.04) and of course these cells have a very low internal resistance so current passing between them would be high. I understand the BMS will trigger a dash warning at 0.1 V deviation which would mean that the defective cell would have to be in fairly bad shape, which I suspect is why they were not able to detect the onset of runaway failure in all cases with software updates. But, I believe that limiting SoC to under 80 or 90% is very effective at limiting dendrite formation from the anode through the separator, which seems to be what causes the leap between the "folded anode" manufacturing defect (clearly visible in the sectional cutaway view of a Bolt cell) and a thermal runaway event, or what engineers call "a fire".

 

Here is the power use/cost of my 2021 Kona EV in April @47,810km. (Wide sheet and there are some holes in the info and some weird numbers here and there - I am not perfect )
I normally charge to 80%, which next morning reads as 79%. The green/black character colour change shows switch from ECO to Normal driving. I drive in ECO mode during the winter to have finer torque control om ice. The Kona range, according to government data is 415km. Columns L and M show range extrapolated from to 79/80% SOC to full charge. L with climate ON, M with climate OFF.

Column P shows the hours needed to charge from the dash , I break it out 1/10 of hour.
Column Q is my calculated cost at overnight rate @0.074c/kWh plus including other charges and tax. I came to the actual cost of 0.1275c/kWh
Column S shows what the 'hydro box' calculates as power used. But their price does not take into consideration delivery, tax etc. So again I use 0.1275c/kWh.

OBDII reading @79% SOC shows Max cell voltage = jumps between @39.7V and 37.8V; Min cell voltage @39.6V (solid)

At this point I am not concerned about my HV battery.

Hope this info is useful.

 

probably not the original owner thats why warranty is as stated.

 

Guys, charge your battery to 100% from time to time to let the BMS know they have a full capacity of 64 kWh.
Also, all the cells of the battery need to be balanced by their voltage on a full charge.

Since you charge your battery to 80% your BMS does not see a fully charged battery and it reflects on your GOM.

Personally, I don't see a problem to charge my battery to 100% frequently. Just don't keep the car charged to 100% for days.
Charge in full and drive on the same day. There is a little buffer even if you see 100% on a GOM.
So 100% is not true full charge

Probably you saw that the regen still works on a full charge. It means you have a buffer in your battery capacity.

 

Your advice is unique, but it goes against the most common concept/belief of charging EVs, unless you have a battery with LFP chemistry in your car. At least that is what I recall from the 'Tesla world'.
The truth is that no one is absolutely sure.

• There will be an upcoming EVS meeting with Jeff Dahn - https://www.dal.ca/news/2021/01/19/advanced-battery-scientists-join-exclusive-tesla-partnership-at-.html
  
• You may want to participate is you can. Follow https://evsociety.ca/calendar/

 

That's not always necessary. I haven't charged past 70% since last Oct and my GoM shows over 500 km at around 16°C battery temp and all cells are in perfect balance. The BMS knows the charge level from the open-circuit pack and cell voltages. I made the graph below based on LG Energy's specifications for the original E63 cell used in the Renault Zoe and Kona.