Charging to 100%? Is it that bad?

[the_burninator]

Tesla themselves, and almost every other vehicle manufacture explicitly recommend not charging to 100% unless needed for a road trip for this exact reason.

Just follow the recommendation of the manufacturer and charge to max 90 unless you need it for a long journey.

Where, specifically, is this explicit recommendation from Tesla?

I own a new Model S Plaid, and I have searched the owner’s manual for such a recommendation. Maybe I overlooked something, but I couldn’t find it.

(So we’re on the same page, I don’t consider statements by Elon Musk to be manufacturer recommendations. I’m not saying that you do, but I have seen other people referencing Musk statements in this thread, and I want to make sure we’re talking about the same things.)

 

[STS-134]

Where, specifically, is this explicit recommendation from Tesla?

I own a new Model S Plaid, and I have searched the owner’s manual for such a recommendation. Maybe I overlooked something, but I couldn’t find it.

 

[boombap]

Where, specifically, is this explicit recommendation from Tesla?

• What percentage should I charge the battery to?
  For regular use, we recommend keeping your car set within the 'Daily' range bracket, up to approximately 90%. Charging up to 100% is best saved for when you are preparing for a longer trip. You can adjust how full the battery charges from the charge settings menu.

Source: The FAQs

 

[DaveNN]

I'm at -1.5%
8k miles since March 22,from new.

 

[MartinA65]

I have a MIC SR+ LFP. I only cover about 4000 miles pa so the advice to charge to 100% once a week is tricky as sometimes I don‘t need to charge every week. When I do I tend to charge to 80% overnight on octopus Go and then top it up to 100% just before I drive. I do this so that the battery isn’t left standing for 4-6 hours at 100%.
Is this necessary or am I being over cautious? Also I usually charge from about 40% will that be enough for the BMS or do I need to sometimes charge from lower, around 20% ?

 

[Jason71]

I have a MIC SR+ LFP. I only cover about 4000 miles pa so the advice to charge to 100% once a week is tricky as sometimes I don‘t need to charge every week. When I do I tend to charge to 80% overnight on octopus Go and then top it up to 100% just before I drive. I do this so that the battery isn’t left standing for 4-6 hours at 100%.
Is this necessary or am I being over cautious? Also I usually charge from about 40% will that be enough for the BMS or do I need to sometimes charge from lower, around 20% ?

depends on if it's yours or its leased.
Whatever anyone else says NO Li battery LFP or otherwise actually benefits from charging to and being held at 100%
Tesla asks you to do this because the voltage variation on LFP is very small so its easy for the BMS to lose calibration and charging to 100% fixes this.
Doing so does not benefit the battery. The question is how much if any harm does it do it? Tesla obviously think not a lot or they could not recommend this charge strategy even if it does benefit the BMS.
The problem is I am not sure we really have enough data to know for sure independently.
If you don't do it the worst that can happen is the BMS is out of whack so the car may show inaccurate range so I would not stress about doing it only every few weeks.
As for the leaving Standing for 4-6 hours at 100%. I personally would not do this every day whatever Tesla says. Once every couple of weeks? maybe if I had to. In an LFP.
on my car which is not LFP. If I am doing a long journey I charge overnight to 90% then start charging again an 1 1/2 before I set off. This costs me an extra couple of £ but I consider it worth it since I don't do many long journeys and I own the car.

 

[Owner4523]

That’s the wrong question.

Lithium ion cells suffer from chemical reactions at high states of charge, which do a couple things. The battery cell contains what is called a “jelly roll” basically two sheets of rolled up metal foil, one copper, one aluminium, both are coated with a thin layer of a paste containing the lithium, nickel, manganese, cobalt, etc. If you charge to 100 it begins to cause cracking and other damage in this paste, the more cracks it gets the less energy it can store. There is a secondary issue if something called dendrites which is a process where the chemicals deform and grow spikes, these spikes can pierce the foils in the jellyroll, not only is this bad, it’s potentially dangerous and can lead in very rare and extreme cases can lead to battery short circuits and/or fires.

Tesla themselves, and almost every other vehicle manufacture explicitly recommend not charging to 100% unless needed for a road trip for this exact reason. The same reason Apple have implemented a smart charging process for iPhones where once it has worked out what time you wake up in the morning, it’ll only charge to 80% overnight, then a short while before you wake will charge to 100% so that the battery spends as little time as possible at that maximum charge which will cause problems with accelerated degradation. How much that is is impossible to put a generic number on, it’ll depend if you’re doing it at a supercharger or at home, if you’re leaving it a 100% for a day or a week. regardless, however you do it your battery will degrade faster that someone charging to 80%. Furthermore, it‘s just a waste of time. Above 90% you’ll get a max 50kWh charge rate, so if you’re clogging up a fast charger at a slow speed, it’s just poor etiquette.

Just follow the recommendation of the manufacturer and charge to max 90 unless you need it for a long journey. If as per your original post you're having issues with that because of your OCD, that’s a different issue to discuss with your healthcare professionals.

@AAKEE - Here is another post about cracking. What are your thoughts on this? Is this real? Is it something that could give people a pause about charging to 100%?

 

[AAKEE]

@AAKEE - Here is another post about cracking. What are your thoughts on this? Is this real? Is it something that could give people a pause about charging to 100%?

I didn’t read it all.

Calendar aging causes the absolut most part of the degradation during the first 5-8 years. The cycles cause very little degradation, for the majority of the owners.

Using the low SOC stategy will reduce the degradation so much that you can Supercharge whenever needed, charge to 100% whenever needed and still have much less degradation than the most people that charge to 80% and think they baby the battery. If they ”stay out of the microcracking” by never charging higher than 80% will not help.