90%

 

90%

 

Officially 90% but personally I always charge to 80% unless I have a reason to go higher...

 

90% is the maximum recommended but if you really want to maximize the life of the battery, then keeping it at 40-60% is the best -- there are other threads here that provide the data to back that up.

So if you only use 20-30% per day, let's say, then set the limit to 60%. No need to keep charging to 90% unless there is a need to have that capacity for unexpected trips.

 

I usually keep the battery between 20% and 70% in my everyday use. Sometimes charge up to 90%. I try and not let the battery sit too long above 90% or below 20%. These seem to be pretty good rules for battery health without being too annoying. I've also heard somewhere there is a specific stress point in this particular Polestar battery at 70%, so try not to let it sit too long right there either. But ultimately I don't overstress any of it. Haven't seemed to lose much range at all over almost 3 years, even predominantly fast charging.

 

At 95K miles I also don't have any discernible range loss, with a ton of fast charging in the first two years (11,067kWh to be exact!)

 

At least for a 2024 P2,
My interpretation of the manual is this.....

• Do not set a Very high charge level (over 90%) unless you need it for an almost immediate journey. Hence the common understanding that setting 90% is a good level to maximise 'range ready' levels whilst not being VERY high. So 80% even 70% would also be a decent 'battery health conscious' level if you don't need that extra range on tap.
• The 40% to 60% is stated for leaving the car parked up for longer term (more than a month). I guess this still wouldn't hurt on a day to day basis either but it does beg the question why you would buy anything but the standard range model (if you didn't) and then only ever need the 40% to 60%.
• Also, using an AC charger is more battery friendly.

In summary if you don't need the range in the bank, 70% to 90% sounds an insignificant difference and either end of this would be fine depending on your preferences in being range ready.

Edit
Well Time rolls on, you live, learn and ponder making new decisions.
I'd like to point out these posts

#29
#37
#43

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It depends on how much you drive it … when it’s sitting, the closer to 50% the better, so don’t charge it to 80 or 90 if you’re going to let it sit a long time. But if you drive a lot every day, then charging it to 80 or 90 every night won’t be an issue since it won’t sit there long. Personally, I work from home so I charge to 70 once or twice a week and don’t normally run it below 40. But for road trips I’ll charge to 90 or 100 so I can avoid fast charging en route with no worries.

 

@All, appreciate the very helpful responses.

I am closest to @Jupiter7 in my work life so will likely follow his approach in that i) I will keep the car between 20% and 70% daily and ii) will charge to 90%+ when going on journeys that need the range.

Thanks to all!

 

To anybody 'normal' out there thinking about buying an EV - don't worry. You don't have to spend your waking hours thinking about this stuff at all. Set your limit to 90% and all will be well.

 

I’m probably a heavier user than most people (19,000km in 5 and a half months—80% long distance drives of 350-600km several days a week). Typically I charge to 80-90% at home (some of those long drives are at a moment’s notice), or 100% when a long drive is definitely on the menu. When doing DCFC, I usually charge the recommended amount to reach the next station, or 80% if I’m doing something else like having a meal.

Since I’ve had the car (29 October 2024), I’ve only had about 10 days total where weather is ideal (15-22C without rain). I’ve had far more long trips in -15-25C with heavy wind and moderate to heavy snow, and I’ve been on winter tires since 10 November. As a result, I don’t know if I’ve had “first year range decline” common to many EVs. What I do know is I have no complaints about the range I do get relative to the prevailing conditions so far (wintry, mountainous, autoroute/interstate speeds averaging 115-120km/h). I am looking forward to non-winter weather and summer tires to get the best possible results at some point.

 

I do 80% in the summer, 90% in the winter, this ensures I get the range I need (need 120 miles+).

Being in spring, I've left it at 90% right now, but most days it's warm enough I'll likely drop it to 80%. But with all of that said, it's safe to just leave it at 90% all the time, otherwise Polestar wouldn't have suggested that.

 

The Polestar recommended charging limit to preserve the lifespan of the battery is 90%. When you need to go on a long trip, charge to 100% but do it about 2 hours before you leave so it's not sitting at max level for longer periods as its not good (long term) for the battery. When on the road and using fast chargers, charge to 80%.

 

I remember the Out of Spec video where Kyle Conner said that a polestar engineer told him there was a 70% 'stress point' but I have never seen anything else about it anywhere. Has there ever been another source for this claim?

 

Yes, this is the same place I saw it too, and the only time I've heard it. Doesn't sound like something you'd just make up, and also something Polestar might not want to be putting out there themselves. It may be hooey but I do try and avoid my car sitting at 70% just in case.

 

It's important to remember that you never can charge to 100%. The 100% you see in the car is a Polestar set limit, it is not a true battery level. In the same way, you cannot totally drain the battery packs. Tesla allowed you to get closer to Zero because it helped increase their Range numbers. The reason you don't charge to 100% on a Level 3 charger is because 80% to 100% takes about as long as 0% to 80%.

90% is fine for at home charging. If you are going to leave it unused for a week or more, keep it between 40% and 60% (the normal storage charge % for the batteries). 80% at a Level 3 is a nice courtesy for others waiting to use the charger.

 

Lots of good advice, but don’t overthink or worry about it too much. Someone runs a red light and those 70 some kWh are all going to the big charger in the sky.

 

Ever since I got the performance upgrade on my Polestar 2, I like charging it to 90% — it lets me enjoy the extra power for longer now since the boost is disabled under 70%.

 

Well it is not disabled per se but the difference becomes less noticeable as you go below 70%

 

Wouldn't this depend on what the electronics and software is doing? As I understand things, the battery is not connected directly to the motor(s), indeed the motors are AC anyway and wouldn't even work if this was the case. So it could be a bit like 100% charge not actually being 100% of the battery capacity to allow for a bit of headroom by the BMS. It's probably also the reason that we can buy a performance upgrade that is purely software. In other words, there's a lot more going on than might appear from a simplistic anaysis of battery SoC. Also, I can't say I've ever noticed any difference in performance between 100% SoC and 15% SoC (the lowest I've ever got to), but perhaps that just means I'm not driving like a maniac all the time

As for the question posed by this thread "what is the correct charge level", this surely just begs a further question about the definition of "correct". 'Correct' for battery longevity? 'Correct' for performance? 'Correct' for range? 'Correct' to avoid worrying that I'm doing something wrong?

My take on this is that Polestar offer an 8 year warranty on the battery with no contractual conditions regarding how the battery is charged, which as we all know can vary a great deal from slowish AC charging to rapid fast DC charging. The only advice they provide is to recommend limiting charging to 90% in order to maximise battery life, but that's just advice and not a contractual condition. So, I take this as meaning that if I only ever DC fastcharge to 100% then the battery is still going to be in good condition after 8 years, unless it is faulty in which case the warranty would kick in. Assuming the warranty is pessimistic, as most are, I'm not losing any sleep over the 'correct' way to charge it.

For the record, I mostly AC charge at 7kW to 80% at home unless I have a long trip in which case I charge to 100% the night before, and I avoid DCFC as much as possible, not so much for the battery's sake but simply because it's about 10x more expensive than using my home charger!

 

All great points.

As the OP, I was asking the question in terms of longevity but am interested in the other aspects that you raised as well (i.e., for longevity, for performance and for range).

 

It was 80% just like tesla in the beginning, then they wanted to sell more cars and changed it to 90%.
90% is just marketing

 

Obviously if you have home charging and don't need the full capacity of the battery there's no need to do any potentially harmful practices, but generally speaking, the worst possible thing you can do to your EV battery is leave it for an extended time at either very high or very low state of charge.

Most important of all: you've bought (or leased) a car - use it for the purpose you have it and don't let perceived battery deg stop you from doing so. Eventually second hand buyers will accept they are buying a used product that may not have the original advertised range - just like very few ICEs will be capable of achieving out of the factory performance or mpg when they've been used for a few years, or a second hand iPhone might not last you two days on a charge like a new one could.

 

I charge mine to 100% every single day, just for the hell of it

 

The most important factor is to minimize the time your battery spends above certain thresholds, where there is a sudden increase in wear.

For NMC those are at around 60 % and around 95 %.

Due to buffer and degradation, this equals about 55 % / 90 % displayed SoC.

Ideally, keep the SoC at or below 55 % SoC for as much as possible. When travel requires more, just charge more, as it doesn't matter much then in the grand scheme of things.

For extra care, a lower SoC is beneficial so optimal long term storage SoC is around 20 to 30 % SoC. However at normal temperatures (25 C) it's only really relevant to minimize the time beyond 55 %, no much difference below.

 

What is NMC please?

 

So is this how it goes then?

Mr Polestar: "Hi Mr Customer, thanks for buying your car with an 82KWh/220kw battery. Here have this new winter coat."
Mr Customer: "Really ? thanks what's that for?"
Mr Polestar: "For when you are putting your car on charge."
Mr Customer: "Sorry, I'm a bit lost. I just nip out occasionally and plug it in right?"
Mr Polestar: "Sort of, but you should be keeping the battery state of charge at less than 55%"
Mr Customer: " Go on then what's the punch line? the manual recommends 90% thats OK isn't it?"
Mr Polestar: "Ummm.....It is but really what we haven't told you is that 55% to 90% you are doubling the aging and increasing degradation rate".
Mr Customer: "So, I thought the 90% took care of the battery? are you telling me it's not?"
Mr Polestar: "Well, just charge to 90% when the journey needs you to."
Mr Customer: "That was my understanding for when to charge to 100% and that 90% is fine the rest of the time."
Mt Polestar: "55% and under is better."
Mr Customer: " So for everyday use then, preserving the battery, the WLTP figure of 409 miles should be changed for real world representation to something that aligns with 55% of that if you want to look after the battery? which in my rough calcs is WLTP of about 210 miles or in reality in mid winter considerably less? maybe 140 miles or so?"
Mr Polestar: "Something like that"
Mr Customer: "140 miles is naff all, I'll need to charge way more often if thats the case, especially in the winter."
Mr Polestar: "Try your coat on, lets see how it fits."

 

So is this how it goes then?

Mr Polestar: "Hi Mr Customer, thanks for buying your car with an 82KWh/220kw battery. Here have this new winter coat."
Mr Customer: "Really ? thanks what's that for?"
Mr Polestar: "For when you are putting your car on charge."
Mr Customer: "Sorry, I'm a bit lost. I just nip out occasionally and plug it in right?"
Mr Polestar: "Sort of, but you should be keeping the battery state of charge at less than 55%"
Mr Customer: " Go on then what's the punch line? the manual recommends 90% thats OK isn't it?"
Mr Polestar: "Ummm.....It is but really what we haven't told you is that 55% to 90% you are doubling the aging and increasing degradation rate".
Mr Customer: "So, I thought the 90% took care of the battery? are you telling me it's not?"
Mr Polestar: "Well, just charge to 90% when the journey needs you to."
Mr Customer: "That was my understanding for when to charge to 100% and that 90% is fine."
Mt Polestar: "55% and under is better."
Mr Customer: " So for everyday use then, preserving the battery, the WLTP figure of 409 miles should be changed for real world representation to something that aligns with 55% of that if you want to look after the battery? which in my rough calcs is WLTP of about 210 miles or in reality in mid winter considerably less? maybe 140 miles or so?"
Mr Polestar: "Something like that"
Mr Customer: "140 miles is naff all, I'll need to charge way more often if thats the case, especially in the winter."
Mr Polestar: "Try your coat on, lets see how it fits."

There is not only one optimization target.

Polestar will - reasonable speculation from my side - optimize variables so that the battery will have 70 % or more after 8 years (garantuee) while under the constraint of having the car and charging instructions as simple as possible.

They will internally have more complex models, together with CATL, but the above is a reasonable minimum because for sure they want to avoid battery replacement cost during the garantuee.

Your goal may or may not be identical to the ones of Polestar or it may overlap.

 

Also, I've seen battery specs that include the number of charge cycles they can support. So, if we only charge our batteries to 50% then surely we'll be doubling the number of charge cycles for a given mileage/lifetime, which might also be bad for them.

Frankly, it seems to me there's a lot of 'urban myths' flying around about EV batteries and it's difficult to see the wood for trees. I presume that battery researchers and EV manufacturers have spent billions developing this technology so where's all the real scientific data about it? Or are we really reliant on the modern equivalent of 'a bloke down the pub' for information?

Again, given that the only advice Polestar offers is to 'recommend' only charging to 90% while still offering an 8 year battery warranty (along with most EV manufacturers), my feeling is that it doesn't really matter how we charge.

 

"Charge Cycles" are 0-100%, so charging from 25-50% twice is the same as charging 25-75%, on that specific thing.

A lot of this is typical gearhead pedantry though. The same kind of stuff where people run different oil with more frequent changes, replace "lifetime" gearbox oil, run higher octane fuel than required, use the fuel additives, handwash vs carwash, etc. All of these things absolutely add up over the 20 year life of a car, but at the end of the day it doesn't matter for 99% of the population. The problem is with EVs this stuff has gained media traction, so all the non-gearheads are thinking about it.

We're nerds talking nerd stuff. It's a car, just drive it. If you want the super distilled "change oil every 3k miles" equivalent, it's "stay as close to 50% state of charge as possible without inconveniencing yourself".