Well, because it's not the computer's (the BMS, "battery management system") business to limit range or performance for the sole benefit of maximising battery life.

Many EV owners (myself included) tend to think about preserving their expensive investment as a high priority and it's certainly true that abiding by certain rules can help by a tangible margin. No doubt other owners don't care.

I have a Kona EV but it's all the same, lithium-ion cells prefer to be in the middle of the range in terms of both time-based life and degradation from charge cycling.

Tests of Li-po cells easily found on the internet indicate that degradation per full-charge cycle is significantly reduced if the charge/discharge range is confined to the middle of the range. It's important to recognise that a full-charge cycle means that the sum of charges and discharges equals 100%. So charging from 40 to 60% and discharging the same amount results in the accumulation of 1/5 of one full-charge cycle.

Charging from 0 to 100% and discharging that results in one full-charge cycle. If you check out degradation graphs you can see how many full-charge cycles you could achieve down to a certain capacity retention (SoH). Multiply that by the range to see how far you can drive if time-based degradation was not a factor.

(ref: Battery University)

If you as an owner choose to care about battery life it will definitely help to keep the SoC in about the middle. E.g, I tend to stay between 50 and 70% because I'm unlikely to need more and if I do I'll just visit a nearby fast charger for 20 minutes.

Regarding DC charging, I can't provide as much insight regarding the Ioniq 5 because of it's focus on high charging rates and 800V system. But, from the Kona's perspective the cell datasheet from LG Energy Solutions has been "leaked" and it contains test results from "fast" charging. Without getting into too much detail, if I stick to 50kW chargers (tops at 47, but the Kona can do 77 kW on larger units) the effect on battery life is fairly minimal and I won't be worrying about it. If you max out the charging rate frequently there will be higher degradation.

Hope that's helpful.

 

This is very helpful, and I generally follow the 20 to 80% rule. However, is there not a logic flaw in that if you only charge say 40 to 60% regularly, yes it will reduce degradation per charge, but you obviously need to charge it more often which might defeat the purpose?

 

I too am confused, I’ve read every thread on here and I can’t make my mind up if I charge to 80%, 90% or 100% whenever I choose. I understand we don’t want the cars sitting at a full charge for long and it’s not good to go too low. Also the manual states to charge to 100% once per month for balancing. Beyond that I have no idea?

 

Assuming prolonging battery life is important to you just pick a range of SoC that suits your driving requirements. If you typically need 50% of the range per day then you could position that 50% across the midpoint, e.g. 25 to 75% SoC. But you'd also consider that you might want to not be caught out with only 25% in unforeseen circumstances so position the center a bit higher, say 35 to 85%.

If you have a DC fast charger available nearby you can add a significant amount very quickly and can factor that in.

In the end the main thing to avoid when possible is leaving the car sitting at 100% for days or weeks.

If the car is used somewhat randomly perhaps leave it at 80%.

 

Charge rate is mostly a factor as it pertains to heat, but there are many factors affecting battery life (otherwise known as discharge cycles). If you really want to look at the whole picture, here is a pretty complete and concise paper that explains these factors well.

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

 

I have a home charger set to 6kw charging. I have been charging the car a couple of times a week to 100% thinking 6kw is like a trickle charge compared to a DC charger and wouldn't have too much affect on battery life.
What do you think?

 

No, general wisdom is don't go below 20% or charge above 70% unless you need the range for say a long trip to a charger. It's especially important to not leave it sitting above 80% for days in the heat. This has the most effect on longevity.

 

@KiwiME ’s comments above are quite accurate. Just remember Li ion batteries:

• are uncomfortable above 90% & below 10% for any length of time, and
• hate heat.

So closer you can keep batteries to 50% and minimise supercharging the longer they will maintain efficiency and longer they will last.

But it gets complicated beyond that, Eg:

• There are mitigations such as BMS minimising heat buildup that help HI5s.
• Also different battery chemistries (such as Li iron) can work at low/high states of charge, but LiFe batteries are not used by Hyundai.
• etc

 

This discussion is kind of irrelevant. I drove a BMW I3 for 14 months, and during those months the car was driven for 120 000 km ( approx 75 000 miles ) . It was a 2019 model with 42 kWh (120 Ah) battery out of which 38 kWh was usable. Needless to say that i was charging it once a day (at least, in winter i was doing it even twice or three times a day using DC fast charging). I would say around 20% of my charging for that car during the period i had it, was slow charging using a granny charger that i had at home. The rest was always DC charging. After 120 000 km of this kind of usage, charged multiple times a day using DC charging, at 120 000 km, the usable battery capacity that the on board computer was showing, was 38.3 kWh. This was in a service menu that you can access if you know how to do it. So, DC charged all of its life, 120 000 km driven, 0 loss in usable battery capacity. Yes it does charge slower than Ioniq 5 but i stand by the principle. The manufacturer knows how to build a car in such a fashion that no matter how hard you beat on it, it will always deliver.
I doubt that any Ioniq 5 will ever have a problem with battery degradation for at least 5 years of not more than that. And how many of you will keep you car for longer than that ? Ok, if you plan to keep your car for 10 years or more, then you can start to plan how to charge it on a daily basis with a bit more care, and make sure you use slow charging as much as possible, but in all honesty, just use your cars as you need them and stop worrying about battery life / degradation. This is a non issue for the normal life of the car.

 

This discussion is kind of irrelevant.

If this was an i3 forum I'd agree, but it's not. As long as questions are being asked I'll answer them as best as I can.

 

And to that i would add that all of my DC charges with the I3 were usually started from 10-20%, up to 95%, and i have even driven it to 0% a hand full of times and still, no degradation for that battery during the time i used the car (granted it does have a big 4kWh buffer.. as the manufacturer is stating 42kWh gross with only 38 kWh available to the user ... but still... ). I am sure it had SOME degradation, but even after 500+ DC charging cycles, it still had the advertised 38 kWh usable battery capacity. And seeing how battery tech is not that different between manufacturers, i would expect the Ionic 5 to be at least this good, if not better. Use your cars as you see fit, they are very well designed for you not to cater to them, but them to you, so enjoy them, and stop worrying about nothing.

 

Sure thing, if charging to 80% covers 200% or more out of your regular daily usage, (so your range anxiety is 0 at all times) then by all means, limit the charge and do your bit to keep it in the best shape possible.(kudos to you). My point was just that you do not have to worry, as the end user, that you will damage the battery in the long run if you are DC charging it often. They can take it, and then some.

 

My thinking is the issue is analogous to full throttle acceleration in an ICE car. Will occasional full throttle acceleration hurt an average ICE car? Of course not. But if you do it constantly over the course of tens of thousands of miles will it cause undue wear to the powertrain?

Plenty of evidence has been presented on this forum suggesting the absolute best thing you can do is to keep the SOC between between 30 and 70% as much as reasonably possible.

I take it a step further and try to keep it between 40 and 60% when I can. Feel free to accuse me of overkill. but I've always been the type to meticulously maintain my vehicles.

But at the same time I also won't hesitate to go below 10% or fully charge to 100% when I need to. I believe that saying either practice is "bad" for the battery is also overkill. While I doubt my extra effort will make a substantial effort in the longevity of the battery, I believe the miniscule effort required to do what I do likely will make a difference long term, and I plan to keep the car many many years and would like to avoid degradation as possible as much as reasonably possible for as long as possible.

 

One other thing I do to minimize heat while charging is I normally keep my Wallbox on the slowest charging speed possible. Of course when I have a need for a faster charge I won't hesitate.

My charging situation is perhaps easier than some others in that I don't normally drive more than 50 miles in one day and 95% of the time my car is home in the garage with the Wallbox every night.

 

Stop worrying about it. The car has a great BMS and you cannot charge it to a real 100% in any case.

 

Shark, it's clear to me your efforts to avoid degradation are not wasted. My sister and I have identical Tesla Model S (except the colors). We normally use the Level 2 charger in our garage whereas she doesn't have one and almost always uses Superchargers. And she does not generally charge every day the way we do and often waits until SOC is 10-20%. After about 100k miles we've lost 5-8% of our range and she is about double that. Not bad, but it does make a difference.

 

Thank you for posting - very interesting info. On question though. What level do each of you charge to? 80%? 100%?

 

As I seem to be the bad guy not caring so much about battery degradation, I started to think about potential new owners in the future.
If I always charge according to the worst case between 25-100% SOC, my battery capacity retention will be 93% when I sell the car after 4 years.
What happens to the battery degradation graph if the new owner is a good guy, and starts to take care of the battery by keeping the SOC between 75-65% ?

I'm curious to know if the cells can "recover", and follow the best case graph (orange) so, that the new owner still can have over 85% left after 8000 cycles (added yellow curve).
Or have I destroyed and weared out the battery for good?

 

As I seem to be the bad guy not caring so much about battery degradation, I started to think about potential new owners in the future.
If I always charge according to the worst case between 25-100% SOC, my battery capacity retention will be 93% when I sell the car after 4 years.
What happens to the battery degradation graph if the new owner is a good guy, and starts to take care of the battery by keeping the SOC between 75-65% ?
View attachment 38934
I'm curious to know if the cells can "recover", and follow the best case graph (orange) so, that the new owner still can have over 85% left after 8000 cycles (added yellow curve).
Or have I destroyed and weared out the battery for good?

"An interesting discovery was made by NASA in that Li-ion dwelling above 4.10V/cell tend to decompose due to electrolyte oxidation on the cathode, while those charged to lower voltages lose capacity due to the SEI buildup on the anode."

BU-808b: What Causes Li-ion to Die?

BU meta description needed...

batteryuniversity.com

Sounds like there are two primary mechanisms of battery decay that depend on the type of use, but 100%-25% cycles probably do both so I'd imagine that damage is done and the best you can do after reaching 93% on the black line is your yellow line. But maybe that's not even possible as the orange line likely only involves the second mechanism.

 

I’m normally a big fan of ‘set it and forget it’ and yea, you don’t need to babysit or obsess over every single charge or go out of your way to optimize every

If you’re not planning on keeping the car for longer than 5 years you’re most likely fine to do whatever you want since you won’t really see the tail end of the battery’s life cycle.

It’s not any different than a laptop or a cell phone. If you’re constantly trading them in you never really worry about it. If you’ve owned a phone or laptop for longer though, you begin to notice how much faster the battery runs out. (Especially if you keep it plugged in all the time).

The difference is I can replace my phone battery for $100. Replacing an EV battery to get your performance back is going to be over $10,000.

So even in that instance I would still say just use the car the way you need to use the car. But you should really be aware of these guidelines if you want and need your investment to last longer. (Especially with the deprecation hit you’re already taking owning an EV).

 

If you’re not planning on keeping the car for longer than 5 years you’re most likely fine to do whatever you want since you won’t really see the tail end of the battery’s life cycle.

But unless you are leasing, don't forget when you go to sell or trade in the car any knowledgeable buyer or dealer is going to be looking at the condition of the traction battery irrespective of the remaining warranty. If you don't believe that just look at how some used Model S Teslas that are 5 years or older are being marketed today.