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Just delivered P2 has 90% as recommended battery charge

10K views 40 replies 18 participants last post by  fabrice 
#1 ·
Just sharing for all, I just received my P2 this morning and I noticed that the recommended charge by Polestar is now 90% and not 80% as I was reading a lot on this forum (sorry it is in French but I guess it is clear for all :) ):
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#7 ·
Interesting. Ipace owner here. Possible P2 in my future. Jaguar just says charge to 100% as much as you want. Won't hurt. I know Tesla also doesn't recommend charging to 100. The Ipace keeps a large buffer of 5 kWh to protect the battery (90kWh with 84.7 available). I thought the P2 also did this? I haven't seen any battery degradation after 1 year / 19500 km. The Tesla seem to drop up to 5% in first yr.
 
#8 ·
Thanks for the post Fabrice. Good of you to share the update.

I must admit it sounds like psuedo science limiting it to 80%. Unless I misunderstand it, it is all to do with not charging all the cells all the time and therefore reducing the amount of damage done by charging. For example of the cell is good for 100 charges then you can give its life a 25% boost by charging it only 80 times out of 100. Sounds good in theory but I don't think they have the evidence to be conclusive on this.

It's also worth noting that the warrenty is for 8 years 100k miles and as far as I or they know you can do what you want to those batteries. Super charge them twice a day if you want as they can't tell you how to charge them. But it's only if they drop to less than 70% capacity within 8 years that they wil replace them so supercharge them for 8 years and have 71% remaining it's on you to fix them.

I'll stick to charging to 80% because i use less than 20% a day and can plug it on at home whenever but I wouldn't be too concerned if it was charged more as that's a problem for 8 years time.
 
#10 ·
78kWh with 75kWh usable means there's a 3kWh buffer, by definition. That's why the Polestar takes an absolute age to charge fully to 100%, because it's got a very small (indeed) top buffer. It's also why regen is severely limited until you've used a few more kWh. This is why I don't expect to see much range "unlocked" as Audi and Jaguar have done, as they had far bigger buffers to start with.

It's also why the rapid charge curve is agressive to 80%, then suddenly massively drops; they're pushing their luck to hold the charge rate to 80% (for marketing purposes) when really it should taper off evenly. I think they've got all they're going to get out of the battery.
 
#12 ·
I'll have to watch Bjorn Nyland's tests again - he normally calculates the actual amount available based on his low and high speed test runs...
 
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#16 ·
Well, it's 72.8kWh that's gone into moving at 90kph, and 69.8kWh at 120kph - it varies due to the internal resistance of the batteries having a self-heating effect which increases as the temperature rises (due to increased load on the battery), so I'd suspect without this effect, i.e. purely in terms of available capacity, it's 75kWh usable. In other words, if you drove (almost) endlessly at 10mph, you'd probably measure around 75kWh.
 
#22 ·
That will take a while, but is expected. I guess that is why PS suggest 90% as the normal maximum.
I will certainly be going to 100% if I need to do a long journey, but for nomal use 80-90% is fine for me (working on the basis that 90% gives me 180 (winter)/ 200 (summer) usable miles). I would normally look to charge at no lower than 15% (prefer 20%) and typically my bladder gives in long before I get to that point.
 
#21 ·
And so you should. I'd ignore the 80/90% thing whenever you need the range.
 
#23 ·
Is it possible to approximate usable battery by measuring the battery percentage increase when you use your home charger vs the kWh input of your home charger. For example I charged up the other day from 68% to 80% at home and Podpoint recorded 8.4kWh of charge which is 0.7kW per % so 70kW for 100% (usable capacity)
 
#24 ·
It will depend heavily on the efficiency of the on board charger for 240V mains; generally they're about 85-90% efficient, so if you look at the kWh put into the car, then multiply by 0.9, you'll get a rough idea of how much of it went into the battery. You ideally need a big step, not just 12%, as otherwise rounding errors become significant - for instance that could be 68.49% to 79.5% (about 11%) or 67.5% to 80.49% (about 13%).
 
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#26 ·
So I think we might be getting closer to 70kW usable.

Last night I returned home with 25%. I charged last night I set the charge limit to 90%. So that's 65% of the battery to charge up.



This is what the Andersen A2 Charger said it had delivered. Assuming zero loss that would be 45.8kWh / 0.65 = 70.46 (note: There would be some loss, but for now ignore that)

From my Trip Computer yesterday:
1773


( 122.6 / 100 ) x 37.5 = 45.975 kW used.

This is within margin of errors (45.97 vs 45.8) - So what I used on Sunday was replaced last night, as I started at 90% yesterday and charged back to 90% last night.

So conclusion ... either we are getting less than 70kW of usable battery, of the software is doing some odd things with the battery % reporting (or a 3rd is my math is terrible)!

Are we really getting =<70kW from an 78kW battery ?

Or is there some extra hidden battery below 0% the car isn't telling us for idiots that drive to 0%?

The only way to know is to become one of those idiots. I'll have to fund a car park with a working charger, where I can drive around in loops until I get to 0% and see what happens.

So I'm am hopeful that Polestar can not only address the high usage at the starts (hopefully via pre-conditioning app) and/or unlocking more battery later on, as there seems to be a huge chunk we could access.

Is my maths right? What's your thoughts / experiences?
 
#27 ·
The trip meter is showing an average, not actual consumption. So you're seeing rounding errors on top of rounding errors on top of rounding errors... Every time that thing updates, every few seconds, the quality of the data is degraded.

Unfortunately, what is missing is, ironically, the simplest instrument to implement. Just show us how many kWh have been consumed since the trip meter reset! Then these sort of calculations could be done accurately.
 
#28 ·
The trip meter is showing an average, not actual consumption. So you're seeing rounding errors on top of rounding errors on top of rounding errors... Every time that thing updates, every few seconds, the quality of the data is degraded.
I get that hence why I said it seemed to be within margin of error. Plus it does seem to match up with how much my Charger distributed to how much on average was used. Obviously again there will be a small lose in the car transforming AC to DC, but we don't know what that is ... it wasn't meant to be perfect science but a ball park figure.

My point was though .. it does seem that based on 65% of the battery we are getting =<70kWh usable.

I could try and get a 0-100% charge and use the A2 it would tall me how much it pushed out, then we could assume a % of loss ?
 
#29 ·
Just to be clear - I wasn't criticising your workings. It's annoying the car won't show actual kWh used. You're doing the best you can with duff data.

I think assuming 90% charging efficiency is reasonable and erring on the generous side. So that means your charger put 41kWh into the battery.

With that 41kWh, you added 65% charge - so that's an even worse capacity of 63kWh. This clearly cannot be correct which means there are just too many unseen variables.

There may be a non-linearity with the charge level indication for example, or some other weirdness.

Until we get some kind of app access like LEAF Spy, this will all remain a mystery I expect...
 
#30 ·
Without even having a car yet I dare not enter into such technical discussions as I can’t replicate or add to the experiments.

All I can state is what was passed to me some weeks back in that capacity is being held back and will be released at some future point. I don’t think this was simply conjecture but take it as you will. Maybe this has some sense to it if PS are gathering real world usage data?
 
#31 ·
Maybe this has some sense to it if PS are gathering real world usage data?
Jag did it ... Tesla did it ... not sure if Merc/Audi did it though ... but it's not uncommon for this to happen. What confuses me is that Geely make a lot of EV's in China so would have some idea to start with, plus this car has had over a year of testing ... although maybe not with the final mass produced parts, Who knows?

@stevelup I agree something isn't being reported correctly or we really are only getting a lot less battery usage! I'm hoping too for a Leaf Spy like app or an OTA update that shows us more info & data!


I'm just glade both nights this weekend were almost free from Octopus Agile! :D
 
#35 ·
I did the same too and came out with 70kWh (less if including charging losses). 8.4kWh from home charger to get from 68% to 80%. Although as some have said % is not likely to be very accurate measure . Even if it was accurate, rounding to zero dp still makes it inaccurate.
 
#33 ·
It's clear to me that the percentage shown is not accurate, just like the gas gage in an ICE car. This makes sense, too, as it's bound to be pessimistic as you get low. Hit near zero percent on the meter and you've got more in the tank, so to speak.

It's probably some sort of curve...
 
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