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Kia E-niro 4+
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Discussion Starter · #1 ·
So… literally anywhere and everywhere you read about Li ion batteries and EVs, the suggestion is to only charge to 80% or 90% to prolong the batteries operational life and capacity. It’s told as an objective fact.

I’m about half way through the manual (yawn, apart from the funny typos (alcohole anyone?))…. But nowhere in the manual tells me to charge the car to 80% to prolong the batteries life.

Even though it tells me not to exit the vehicle when it is moving, don’t drive from the boot, and don’t clean the seats with alcohole!

Surely if something is as objectively true as the webz suggests, it would be mentioned in the manual.

I’m sure I read somewhere that the gross capacity of the e-Niro’s battery is 67kwh, with a net capacity of 64kwh.

Could it be that we’re limited to 64kwh to avoid overcharging the battery - and that for this specific platform (and other that do similar) the 80% rule doesn’t apply - because it’s managed by the vehicle?

Just wondering, becauseI left it to charge to 100% for my first home charge, and plan to run it down to <20% to get a feel for range, charge times etc. I plan to then set the charge limit to 80% after that. But wondered if I’m reducing my range by ~50 miles because…. Well, the internet sez so?!

I’ll be driving about 250 miles a week, so it’s not like it will be sitting there 100% for days on end.

I’m not trying to be narky, just trying to understand the car.
 

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The battery longevity is best preserved by keeping between 20-80%, though it says to charge to 100% once a month to balance the cells. If you are driving 250 miles a week then you don't need the full capacity every day, so charge to 80% then again when it drops to 20% then 100% once a month or if you are going on a journey in excess of the car's range.
 

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64kwh is a lot. At 1,000 cycles, charged to 100% and discharged to 0%, driven badly with lots of hard acceleration and deceleration, it’s still 150k miles. How many miles on your battery warranty again?

so, treat it bad and you’ll still not need to claim on warranty, but treat it nice and it’ll still have good capacity at 300k miles and 15 years of age.
 
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Discussion Starter · #4 ·
64kwh is a lot. At 1,000 cycles, charged to 100% and discharged to 0%, driven badly with lots of hard acceleration and deceleration, it’s still 150k miles. How many miles on your battery warranty again?

so, treat it bad and you’ll still not need to claim on warranty, but treat it nice and it’ll still have good capacity at 300k miles and 15 years of age.

Well this is the thing, it's a lease car, so we're getting rid in 4 years, no matter what.

We drive ~12k miles a year, so will be no where near that. Assume one charge a week, 230 miles on average, seems reasonable. 52 charges a year. ~>400+ charges during the lease.

Ignoring the reality that we drive about 180 miles a week, with rest coming from the odd longer trip... details eh :p It's still a long charge once a week or so.

That makes the car convenient to run, as well as well as nice to drive and cheap to run. Which was my trigger for going BEV over ICE.

I have a pang of guilt about the next owner - but unless my employer, the leasing company or the manufacturer say only charge to 80%, I'll charge to 100%. I will report battery back degradation at the end of the lease!

My grandparents used to say never run a fuel tank dry because it has dead birds or slugs or something-or-other in it. And couldn't move on when fuel is better filtered, cars have their own filters and no longer last 30+ years.

I think what I'm trying to say is that surely car manufacturers would have thought their way around this problem with the more mainstream EVs? They are being bought by less and less enthusiastic electron-heads (if that's a term... should be :) - I can't imagine most people I know sticking to the 80-20% rule.

With the current gen of cars - it's like the guy putting tiger repellent on the London train........ But there has never been a tiger on the train! I wonder if the 80% rule is built into the cars with extra unadvertised capacity in the current generation? But there is a hangover from early EVs which persists unchallenged.
 

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64kwh is a lot. At 1,000 cycles, charged to 100% and discharged to 0%, driven badly with lots of hard acceleration and deceleration, it’s still 150k miles. How many miles on your battery warranty again?

so, treat it bad and you’ll still not need to claim on warranty, but treat it nice and it’ll still have good capacity at 300k miles and 15 years of age.
This from a post by Xinix 8 months ago:
There´s ample information on this subject over at BatteryUniversity.com. See e.g. this page:
TL;DR 300 - 500 cycles when charging at 100% for NMC cells, 600 - 1000 cycles when charging to 85-90%, 1200 - 2000 cycles when charging to 70-75%.

I imagine these figures are based on maximum capacity of the cell chemistry, too, i.e. 67kWh. Also, cycle life is not to be taken literally - think of all the charging and discharging that goes on as you drive - rather it is a standard way of measuring the total amount of energy that a battery will deliver before its capacity degrades excessively (80% of original?) and is also typically based on 80% depth of discharge. So...

67 x 0.8 x 1000 = 53,600kWh at 4 miles/kWh = 214,400 miles. So, yes, 300,000+ if kept to a moderate state of charge most of the time, especially as even 100% SoC is only around 96% of total.
 

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I have a pang of guilt about the next owner - but unless my employer, the leasing company or the manufacturer say only charge to 80%, I'll charge to 100%. I will report battery back degradation at the end of the lease!
Would it really inconvenience you that much to only charge to 80% or 90% and by doing that knowing that you will extend the car's useful life with a couple of years? Even if the next owner is anonymous, they will be a real human being, they will be stoked with having an EV that will probably be the first one they own and they might even plan on owning it for 5 or 6 years. Wouldn't it be nice that they got the best experience they could have, just because you could be bothered to plug in 5 times a month rather than 4 times a month?
 

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Discussion Starter · #7 ·
It's interesting stuff - I'm not trying to be awkward in any way, just chewing the fat as it were. Getting an EV as a lease car is a bit of an experiment with a known exit strategy. I think this will be our last lease car via work, and this is all feeding into my decision on what to do at the end of the lease. A needy 150 mile car which needs plugging in and will be a constant range-worry isn't doable for us.

An 80kwh Enyaq (for example), providing it's not going to need plugging in and out all the time might just tip the ownership balance for us. We are constantly in and out during the day and evening, so actually charging little but often will be a right PITA. It might only add 4 minutes to unplug, tidy the cable away at the start and end of each journey - but multiply that by 6 ins and and outs a day and it soon adds up. Especially when the kids are rabbiting on about who hit who in the playground, look at this 6000th picture of a distorted house, as well as nipping here, there, everywhere for work... It's an additional stress I don't want, and one that made earlier EV's incompatible with my needs.

If I can charge once a week (OK, once every 6 days and take it to 90%) and that combined with the car's on safety margin will reduce the battery wear to an acceptable level for a 10 year ownership - I would take that. The 64kwh battery is just on the margins of being doable. An 80kwh battery will (probably) allow me a once-per-week charge and keep that battery between say 15 & 85%, even accounting for some degradation.

I expect manufacturers will need to account for the known limitations of Li batteries in their engineering if these cars are to become mass-market. Most people won't faff around with charge limits etc, they will fill up and go. The cars need to be OK for those people.

I'm still not convinced that, in order to keep my lease car in an OK condition, that I should not regularly charge the SOC indicator to 100% (OK, 90%). Genuinely; not just in a trolling/antagonistic way.

I know Li cells benefit from such treatment, It's the resulting batteries consisting of those cells where my doubts are creeping in.
 

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Unfortunately, some of the battery hyperbole has become EV folklore. If the manufacturer doesn't specify that you should regularly charge to only 80% or doesn't specifically prohibit you from charging to 100% then you don't have to worry about it. The battery will almost certainly outlive the car.

However, in some cases, charging to 100% limits the amount of regen you can get as there is nowhere for the power regenerated to go and so they regularly top up to 80% or 90% so that they have regen available when they start off.

Then again, I may be having to scurry around in the shadows from now on as the pitch forks and clubs are wielded against me for my heresy for worrying about charging to 100% all the time. :rolleyes:
 

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Here's another pov. I haven't tested this and, frankly I don't have good enough metering and can't be arsed... but, does the charging efficiency drop significantly when you get up near 100%. The rate certainly does and I know the onboard chargers are not as efficient when running at 2.2kW from a granny charger.

So if you always charge to 100%, is that costing wasted power in lower efficiency?
 

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Discussion Starter · #10 ·
Here's another pov. I haven't tested this and, frankly I don't have good enough metering and can't be arsed... but, does the charging efficiency drop significantly when you get up near 100%. The rate certainly does and I know the onboard chargers are not as efficient when running at 2.2kW from a granny charger.

So if you always charge to 100%, is that costing wasted power in lower efficiency?
Good point! Didn't think of that. I can't check it. I did notice it was drawing 6.5kw until near the end of the charge, but I don't know if it did until the end.

But again, if the actual gross capacity is 67, it didn't actually get to 100%. It just displayed 100%.
 

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If I can charge once a week (OK, once every 6 days and take it to 90%) and that combined with the car's on safety margin will reduce the battery wear to an acceptable level for a 10 year ownership - I would take that. The 64kwh battery is just on the margins of being doable. An 80kwh battery will (probably) allow me a once-per-week charge and keep that battery between say 15 & 85%, even accounting for some degradation.

I expect manufacturers will need to account for the known limitations of Li batteries in their engineering if these cars are to become mass-market. Most people won't faff around with charge limits etc, they will fill up and go. The cars need to be OK for those people.
If you have a home charger, then the regime would rather be charging it every night to 80% and charge to 100% once a month or whenever you have a longer trip coming up. I don't see any reason for plugging it in for 30 minutes during the day if your daily usage does not exceed 150 miles.

As for the charge limits and the longevity. It's a bit like driving an ICE car to the limits by revving it to the red zone, going full throttle with a cold engine and hammering the brakes for every stop or driving it with some caution. Your warranty will cover everything independently of your driving style, but the car will definitely last longer if you treat it like you love it.
 

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Would it really inconvenience you that much to only charge to 80% or 90% and by doing that knowing that you will extend the car's useful life with a couple of years? Even if the next owner is anonymous, they will be a real human being, they will be stoked with having an EV that will probably be the first one they own and they might even plan on owning it for 5 or 6 years. Wouldn't it be nice that they got the best experience they could have, just because you could be bothered to plug in 5 times a month rather than 4 times a month?
Depends how often you are charging. I charge once a month anyway so 100% is best for AC charging. I try to always charge the day before a trip though so it's sat at 100% charge for a minimum amount of time.
 

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I don’t know how far manufacturers manage the batteries to be honest. The slack capacity 67 vs 64 kWh is probably a combination of avoiding any over charging and also to allow for regen. A complaint I heard a lot early on with Tesla cars was how the braking behaviour changed significantly when the battery was full because there was no capacity for regen.
 

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...

I’m about half way through the manual (yawn, apart from the funny typos (alcohole anyone?))…. But nowhere in the manual tells me to charge the car to 80% to prolong the batteries life.

...
It's on page 6 of my manual. Possibly somewhere else as well, can't remember.

But, yes, it does say that AC charging (vs DC) will prolong the batteries life and also that occasional charging to 100% is recommended,
 

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I don't worry, I charge to 100%.

by the way for the people who are somewhat rabid about not charging over 80%, so you also limit the charging to 80% on your laptop, toothbrush, portable speakers, cell phone, etc.

(you get the drift)

Greg
I don't have an electric toothbrush
My laptop does not allow me to only charge to 80%. But some brands like Dell have an option to limit the charge
I have an alarm on my mobile phone so I only charge it to 85%
 

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I don't worry, I charge to 100%.

by the way for the people who are somewhat rabid about not charging over 80%, so you also limit the charging to 80% on your laptop, toothbrush, portable speakers, cell phone, etc.

(you get the drift)

Greg
I hardly think I’m rabid about it, but yes I do where possible. Some computer manufacturers have a charge limit setting in the bios. I have a couple of old Toshiba machines that at 7 years old will still run on battery for a good 4-5 hours and I suspect that’s in part by looking after the battery.

Apple introduced a change to iOS that links charging with the alarm so although it does charge to 100%, it doesn’t do so until the alarm so the battery spends as little time as possible in a fully charged state.

These are also not reasonable comparisons given the difference in scale of the battery.
 

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the same had been said for smartphones, and I have actually never cared about it. So, I'd say, stop worrying for unnecessary stuff, don't overcharge if you don't need it, but don't be afraid to charge >80%.

a case scenario. I have 77% and go to a place where there is no close available parking spot except for EV. I'm going to plug the car, even if it reaches 90% although I don't need the charge at all at that time.
 

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Unfortunately, some of the battery hyperbole has become EV folklore. If the manufacturer doesn't specify that you should regularly charge to only 80% or doesn't specifically prohibit you from charging to 100% then you don't have to worry about it. The battery will almost certainly outlive the car.

However, in some cases, charging to 100% limits the amount of regen you can get as there is nowhere for the power regenerated to go and so they regularly top up to 80% or 90% so that they have regen available when they start off.

Then again, I may be having to scurry around in the shadows from now on as the pitch forks and clubs are wielded against me for my heresy for worrying about charging to 100% all the time. :rolleyes:

Not only is this very true, but it also shows that very few people have a clue as to why their cars have a sophisticated battery management system (BMS). The BMS does several things, but as its name suggests its purpose is to manage the battery. It will prevent it being over-charged, it will prevent it being over-discharged, it will limit rates of charge and discharge depending on things like temperature, cell balance and state of charge (SoC). It does all this with no user input at a all. with the express aim of ensuring that the battery lasts a very long time, no matter what the user does. The BMS is generally designed to ensure that if the car is owned by the dumbest person on the planet, it will still be reliable and last at least for the period of the warranty.

There is a slight exception to this with Teslas, as for some reason they do allow the battery pack to be charged to a true 100%, and they allow the driver to override the default lower maximum SoC setting that the cars are set to when delivered. Most other EVs have a buffer at the top and bottom of the true capacity, such that 100% displayed in the car isn't really 100%, and similarly 0% displayed in the car isn't really 0%. Manufacturers tend to be a bit coy about the actual size of the top and bottom buffer zones, but some do quote two overall capacity figures, a usable capacity (i.e. the capacity between the indicated 0% and indicated 100%) and a maximum capacity (i.e. the capacity between the true 0% and true 100% SoC). Some people have tried to work out what these buffer capacities are, and there a third party gadgets around that allow a better view of what's going on, although estimating SoC is far from easy from just measuring things like cell terminal voltage.
 

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It's on page 6 of my manual. Possibly somewhere else as well, can't remember.

But, yes, it does say that AC charging (vs DC) will prolong the batteries life and also that occasional charging to 100% is recommended,
Page 6 on my manual just says that you should charge to 100% at least once per month.
There's nothing about limiting to 80% at other times.

Also page 4 says if you are parking up for many months, to charge to 100% before you do so, so that it never discharges fully.
There's plenty about never fully discharging, and about limiting the use of DC charging due to 'stress', but absolutely nothing about AC charge limits that I can see.
By default the charge limiter is set to 100%.

I'm starting to believe that we're overthinking this.......
 
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