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Engineering Explained: How To Ruin Your Electric Car's Battery - LFP Edition!
- Thread starter petercc9
- Start date
Not watching the video.
Just follow Tesla's guidance.
Stop watching battery videos
Just follow Tesla's guidance.
Stop watching battery videos
Well Tesla's guidance changed to 80% in 2023..it used to be 90%+ for how long..a decade? Model S released in 2012.
Note the "Charge Tip" change (in green)...without much explanation either
I keep my (non-LFP) battery at 65%.
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E90alex
Active Member
Tesla guidance is not meant to maximize battery health but to balance customer convenience with anticipated warranty replacements.
If you are not concerned with maximizing battery health then that’s totally up to you. You can follow Tesla’s guidance and most likely not have your battery fail within warranty.
But for people concerned with maximizing battery health and longevity then there are certain best practices to help with that which minimally or don’t affect at all how you can use the car.
That's like where ICE cars these days are saying you don't have to change your oil every 3,000 miles anymore.
They know the car engine will probably survive the warranty period...but you aren't going to be driving it for 200,000 miles doing infrequent oil changes.
And so how much more do you get?
So far Tesla's guidance is showing the Model 3/Y batteries passing 200,000 miles and going strong.
Funny you should mention 200,000 miles. Since that's what the batteries that were mostly charge to 90% are lasting beyond.
Well if this was easily expected don't you think they'd quickly up the warranty and use that as a humongous selling point....
We are talking about getting the most life out of your battery so it lasts for a LONG time..not just simply matching the warranty.
If you want to ditch your car at the warranty...fine. Others want it to last for far longer.
I got 18 years out of my 2005 Honda Accord V6 when I dumped it for my new Model Y.
The reason many of us buy a Tesla new is because we don't trust how a previous owner of a used Tesla treated the battery.
If battery life wasn't an issue ...maybe more paranoid people would buy used ones for 50% off the new price.
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E90alex
Active Member
The answer is something higher than that. The exact number is not relevant. We won’t see the results for many more years and probably never will if we don’t keep the car long enough. But early data does show less degradation in real world with low SOC charging.
You make it seem like low SOC charging is something you really have to go out of your way and inconvenience yourself to maintain and micromanage. There is exactly zero difference in how I use my car whether I charge to 55% vs 80% daily. I still plug in daily. I still only use 15-20% daily. The charge limit is set and I don’t even think about it. If such a minor change that doesn’t affect me and doesn’t require to alter my habits can potentially prolong the life of the battery, then why not?
Of course, if it doesn’t work for you for whatever your reasoning, then it doesn’t work for you. It’s an option. You can chose if you want to do it or not. No one is forcing you to. The data is there to back it up that it’s beneficial. Whoever wants to follow the recommendations are free to do so, just as you’re free to ignore them. But to keep arguing about it and calling it FUD and false is just being willfully ignorant.
Part of it is just also the nerd/geek/enthusiast factor that we want to maintain the battery as well as we can because we find it interesting to do so. Same reason people PPF their entire cars. Same reason people put screen protectors and cases on their phones. Are those things necessary? Of course not. Some people would consider those things a waste of money. But others like to keep things they spent lots of money on the in best shape they can. Even if it makes zero difference at the time they get rid of it.
I agree that these videos aren’t helpful. Most people replace their cars after 10 years and you won’t destroy the battery in that time no matter how you charge it. I’ve got a 7 year old robo vac with 3000 cycles and always at 100%…. Still 75% Capacity. Perfectly usable.
Micro managing batteries like this will put people off EVs. We need everyone to change their gas cars to EVs eventually and most of those people aren’t going to charge to 60% or whatever.
Micro managing batteries like this will put people off EVs. We need everyone to change their gas cars to EVs eventually and most of those people aren’t going to charge to 60% or whatever.
Well Tesla's guidance changed to 80% in 2023..it used to be 90%+ for how long..a decade? Model S released in 2012.
Note the "Charge Tip" change (in green)...without much explanation either
I keep my (non-LFP) battery at 65%.
Why does @petercc9 have screenshots of @Gauss Guzzler 's car?
The video cites the work done by Jeff Dahn who works with Tesla and yes it’s true that charging LFP to 100% often does cause issues with the battery. But in the grand scheme of things, is it enough to worry about? Up to you but I don’t think so.
Take this 2017 Model S 90D with over 430k miles on the original battery and drivetrain. If mine lasts half this many miles (same year and model/version), I’ll be pleased. Mine has over 120k miles. (Granted, not LFP but similar concept.). I don’t fret over the battery. Time may affect the battery more than mileage but so far I’ve only lost about 10% and degradation has slowed.
Take this 2017 Model S 90D with over 430k miles on the original battery and drivetrain. If mine lasts half this many miles (same year and model/version), I’ll be pleased. Mine has over 120k miles. (Granted, not LFP but similar concept.). I don’t fret over the battery. Time may affect the battery more than mileage but so far I’ve only lost about 10% and degradation has slowed.
ucmndd
Well-Known Member
Absolutely shocking that your take is “trust Tesla absolutely without any thinking, facts, or outside influence clouding your judgment.”
The research paper referenced in the video is probably this:
Gauss Guzzler
Safety Score = 42
I feel like part of my soul has been taken.
Maybe but in the US, Average age of vehicles hits new record in 2024, the average age of cars and light trucks is 12.6 years and passenger cars being 14 years and "light trucks" (includes SUVs, most "crossovers", most pickups and minivans), is 11.9 years.
This person in the super mild climate of city of San Francisco charged to 100% all the time on their 2013 Leaf and was down 6 capacity bars out of 12 by the time they reached July 2020: 2013 Battery Bars half way. They ignored Nissan's directions in the manual and I suspect they topped it off and left it at high SoC a lot of the time given 2013 Battery Bars half way. Yes, I know it's not LFP (and a lousy chemistry to boot, they got better with Leafs built on/after 4/2013) but you can't blame lack of thermal management and high temps for that. I bet if they used the 80% limiter that was in '11 to '13 US Leafs, they'd have been down maybe 2 to 4 capacity bars on that build month (a bad one) of Leaf, not 6.
Battery - Electric Vehicle Wiki was a mapping of capacity bars to remaining capacity.
Attaching average temps for SF per Google, as reference.
For me, I have no LFP-based car, but I usually set my car's limiter Mon to Thur to 80%, sometimes lower. In my normal commute 5 days a week on a dry non-winter day, I use 8 to 10% battery for my roundtrip commute. I charge at work for free. There's no reason for me to needlessly beat up my battery by charging to 100% daily. My car's average SoC would be above 90% most of the time. And, I'd have no to little regen each time I leave with 100% SoC.
If I didn't have free juice at work, charged at home and didn't have the fear of having to stay home for awhile due to COVID, I'd probably set my limiter to its lowest possible (I have no Tesla), 50%.
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Because I actually read some previous relevant posts here related to recommended charging levels maybe?That search field on the top right of the page is quite useful...
Here's the thread where he posted the pic:
Tesla app recommending charge level now?
Mine has always said 90% but will check tomorrow when I plug in. Currently awaiting my THIRD HV replacement so don’t currently care what I charge to. Yep, now shows 80% daily charge rate. That won’t get me the range I need in the winter, but awaiting HV batt No3 so see what happens anyway.
teslamotorsclub.com
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That EE video for one thing, only looks/references a single report and another thing is mixing up calendar aging and cyclic aging.
That report, just as most of the things I see people reference to from Jeff Dahn is about cycles.
We need to get one thing straight:
-we will not kill our LFP batteries from cycling them when using the car.
They can litterally do several thousands of 100-0% cycles.
So *any* discussion about how to cycle them from a cyclic aging perspective is going on a hunt on an issue that simply does not exist.
The cyclic aging will be almost undetectable or close to this anyway.
This is only one of several tests showing how little cycles wear on LFP.
The chart shows how many EFC (equivalent full cycles) we get before we have lost 20% (80% remaining capacity).
Just look to the right and compare with NMC and NCA.
Regardless of how we cycle the LFP's we seems to get 3000 FCE. One FCE is driving from 100% until the car stops. This would probably give us at least 300km or 200 mile on a 3 or Y RWD.
3000 x 300 ? 900K km, for 20% loss. This equals about 0.2% per 10K km or 0.4% annual for most drivers. This was when using the worst case scenario of the tested. Most people will do smaller cycles and the curerent rate is not above C/2 (more like C/3-3.5). So we probably are looking at something more like the 20-80 chart with 6000+ FCE....then the annual cyclic aging would be ~0.2% for the average driver.
Hunting cyclic aging on LFP is hunting ghosts.
So we need to focus on calendar aging if we would like to reduce the degradation (which there isn’t any need to, but it is possible).
Calendar aging is reduced by timing charging so the car does not spend a lot of time between 72-100%, where 75-90% probably is as “bad” as 100% or worse.
Maximizing the time the pack spends at 70% or below will reduce the cyclic aging noticable (if the car manages to see the saved capacity is still to be determined).
Charging late, with 11kW AC and driving shortly after the charge is finished does not cause much calendar aging. In the big picture it is not noticable.
That report, just as most of the things I see people reference to from Jeff Dahn is about cycles.
We need to get one thing straight:
-we will not kill our LFP batteries from cycling them when using the car.
They can litterally do several thousands of 100-0% cycles.
So *any* discussion about how to cycle them from a cyclic aging perspective is going on a hunt on an issue that simply does not exist.
The cyclic aging will be almost undetectable or close to this anyway.
This is only one of several tests showing how little cycles wear on LFP.
The chart shows how many EFC (equivalent full cycles) we get before we have lost 20% (80% remaining capacity).
Just look to the right and compare with NMC and NCA.
Regardless of how we cycle the LFP's we seems to get 3000 FCE. One FCE is driving from 100% until the car stops. This would probably give us at least 300km or 200 mile on a 3 or Y RWD.
3000 x 300 ? 900K km, for 20% loss. This equals about 0.2% per 10K km or 0.4% annual for most drivers. This was when using the worst case scenario of the tested. Most people will do smaller cycles and the curerent rate is not above C/2 (more like C/3-3.5). So we probably are looking at something more like the 20-80 chart with 6000+ FCE....then the annual cyclic aging would be ~0.2% for the average driver.
Hunting cyclic aging on LFP is hunting ghosts.
So we need to focus on calendar aging if we would like to reduce the degradation (which there isn’t any need to, but it is possible).
Calendar aging is reduced by timing charging so the car does not spend a lot of time between 72-100%, where 75-90% probably is as “bad” as 100% or worse.
Maximizing the time the pack spends at 70% or below will reduce the cyclic aging noticable (if the car manages to see the saved capacity is still to be determined).
Charging late, with 11kW AC and driving shortly after the charge is finished does not cause much calendar aging. In the big picture it is not noticable.
So did your 2005 Honda Accord have a 15 year warranty?
Do most cars die after 4-5 years? If not, why isn't their warranty longer.
Just because a warranty ends doesn't mean that the product won't last longer. i.e. your Accord!
It really doesn't matter how you treat the battery, Tesla's number come from fleetwide, not cherry picked vehicles.
People worry about the battery when buying used, because they are normally first-time EV owners and are worried about anything EV.
BTW, are you suggesting that no one cares about the engines on used ICE?
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