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How long do EV main battery packs last before failure (not just manageable degradation)?

To start with, I'm not asking this question to attack Teslas or EVs in general. I love my model 3 and wouldn't change it for anything (well, perhaps a new model Y...)

How long do EV main battery packs really last before they fail entirely? I'm talking about battery failure making the vehicle unusable without battery replacement rather than degrading a manageable amount of range (perhaps as much as 50% of range for a 15-20 year old car). I'm assuming here that battery packs won't be repairable though it's interesting to read about repairers taking on this challenge.

I read breezy predictions of 15-20 year battery pack lifetimes with much evidence AFAICT from various sources promoting EVs.

On the other hand I see quite a few posts on here describing battery pack failures in Tesla cars. I also read about severe battery degradation in the first generation of Nissan Leafs.

Do most battery packs last for 15-20 years but an unlucky minority of cars fail before that? Is it correlated to which version of battery technology was used (e.g. Model S 85 vs later generations of Model S battery technology). Is it mainly limited to batteries that have been treated poorly - depth of discharge, frequency of rapid charging, extremes of climate?

Is battery technology too young to have any certainty about this question? Are we in a parallel situation to the early years of ICE engines where the technology was not mature and unexpected failures were common?

Will manufacturers move to making EV batteries more repairable and making the detailed health of the battery more transparent?

Many Tesla model S cars are out of battery warranty now (here in the UK they'll start coming out of warranty next year, I think). The battery replacement costs are huge compared with the value of an 8 year old car. I can see that people who want to own classic luxury cars like the Model S might be willing to take their chances with this.

Is this situation sustainable for mass market cars? In a mature EV market will the used value of a cheaper EV drop to a very small fraction of its value once out of battery warranty perhaps not much more than the salvage value of the failed battery for energy storage applications and just be scrapped as soon as the battery randomly fails one day?

Perhaps we'll go back to battery leasing schemes like Renault to warranty the battery remains usable underwritten by battery's salvage value.

As a contrast my ICE Mazda mx5 was still going strong when I sold it at 12 years old and is still running today at 17 years of age judging by the public MOT test results (the government roadworthiness inspection system here in the UK). Many other cars are running at much greater ages without requiring engine replacements.
 
Forever really. It's not fair to compare to the Nissan Leaf which was almost useless when new and then quickly degraded due to the lack of a battery temperature management system. With only 60-70 miles of range when new, they could barely make it to the junkyard after a few years. It's also not reasonable to expect that the failure rates of Tesla's early battery designs would suggest similar failures with modern packs.

Tesla has stated they will be producing "million mile" batteries in the near future and their current LFP packs could be half way there already. Even the Nickel/Cobalt packs might take 20 years to get significantly below 50% capacity, at which point they'd still be more useful than a brand new Nissan Leaf.

So you can easily imagine half-range Teslas that are completely worn inside and out being the lowest cost car of the distant future. And unlike a junkyard engine, a junkyard battery is relatively easy to install and it's health/capacity can be accurately ascertained beforehand. You won't see many 40-50 year old Teslas on the road in 2065, but probably a lot more than the 40-50 year old cars you see today.

Batteries will not become "repairable". Automakers have no motivation to add that cost and complexity, plus it's extremely dangerous and difficult to repair a pack. It seems daunting today to think of a $22K battery replacement but that's exactly what BMW would charge to replace an engine. And in 10-15 years you'll be able to get a junkyard battery for $2K just like a 10-15 year old junkyard engine.
 
With the Chevy Volts we are seeing about 10 years in the real world. Age seems to be the bigger factor than miles or charging cycles. These batteries are liquid cooled with system buffers on the low and high end. They have been pampered and not abused. I don't see why the Li batteries from Tesla would be any different.
 
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pouches vs cells, just that difference is huge in temperature control. BMS software, with current limits in cold temperatures and that sort of thing, make sure the batteries are never stressed. Not sure the Volt has a bms as advanced as tesla. Redundancy, the way a bad cell can separate from the pack, the rigidity of the Tesla pack. Seriously, go through Youtube videos that show the internals with engineers explaining what serves what purpose. You'll see there'S something to the Tesla packs. Nothing is perfect, there's continuous improvements, but they've done something interesting.
 
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Yes, the Volt has an advanced BMS. The AC is used to chill the liquid cooled battery when needed, even when the vehicle is off, and the pack itself is insulated and rigid. In the winter a heater in the pack is used to warm the battery pack liquid coolant. Unlike a Tesla pack, the system will also not permit the user to charge to 100% or drop it down to zero. Low end discharges are where the real battery damage occurs. The BMS also goes through a cell balancing process at the end of the charge cycle for cell health. The Volt battery packs are never charged at a high rate, so they don't encounter the stress a Supercharger induces. I don't think the size or format of the cell would make a difference.

All Li batteries degrade with time, temperature, and cycles. With systems like those in the Volt or a Tesla, time is looking to be the issue. That's not a bad thing for those of us who put on a lot of miles (myself included). However for those people who who put on low or average miles, and keep cars going for 15-20 years, it's just not going to work for them given the very high pack replacement cost.
 
As a single data point I'm just shy of 248,000 mi on my December 2014 model S. It has been supercharged two to three times a day, run to zero at least a half a dozen times, charged to 100% 100s of times. It's still on the original battery. I think Tesla's BMS is pretty robust. And no, you can't actually run it to zero. Just because it says zero on your screen doesn't mean Tesla didn't reserve a bit. I'm still a year out on my warranty so, hoping! But, I'll probably keep the car either way.
 
That also reflects my point that these can be great cars for high mileage drivers. A non-diesel, gas car would typically be looking at engine or transmission work at that mileage.

A couple questions:
-Why has it been necessary to supercharge 2-3 times daily? I would have thought that the 265 miles (original) rated range would have been plenty for a 5 day work week, even with those miles. What's your normal commuting distance?
-When you say it's been run to zero at least 6 times, does this mean that the car was run until it shut down and required a tow, or zero on the range estimate?
 
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That also reflects my point that these can be great cars for high mileage drivers. A non-diesel, gas car would typically be looking at engine or transmission work at that mileage.

A couple questions:
-Why has it been necessary to supercharge 2-3 times daily? I would have thought that the 265 miles (original) rated range would have been plenty for a 5 day work week, even with those miles. What's your normal commuting distance?
-When you say it's been run to zero at least 6 times, does this mean that the car was run until it shut down and required a tow, or zero on the range estimate?

I ran into financial difficulties and my son's company went out of business at the same time. He drove it Uber for over 2 years. He would set it to 100% before he started (didn't always make it that high) and then charge it during his breaks so that he could drive the rest of the night. Sometimes it would be two or even three times. Never less than once. He did have to get towed, or rather flat-beded, a number of times. We didn't have too many superchargers up in the Pacific Northwest then.

In retrospect I would never have done it. Not worth it financially. True, the car is paid off now, but with that many miles it's also not worth much. So, Tesla as Uber, at least on these expensive cars? Not a chance that it's a financially good decision. Should have just sold it and bought another one a couple years later when I could.

As a side note I have had to have some thousands of dollars of repairs like any car of this milage and value. All the front steering components, all the rear hubs, that sort of thing. Interestingly enough Tesla, at no charge to me, replaced the air suspension pump at nearly 200,000 mi, they said it should have been done earlier. There's actually been about six different things like that that they've done gratis that pleased me quite a bit. Everybody who works at Tesla is actually pretty good. The corporation can drive you nuts, but the people are all pretty dedicated.

Oh and, by the way, I still have people ask me if it is new. The car does look amazing still!
 
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Well 248,000 miles in a more Uber-appropriate car from the mid/early 2010's (35mpg) would have burned 7100 gallons of gas (140,000 lbs CO2), costing about $25,000 in fuel and depreciating by about $25,000 in age/mileage.

Your 2014 Model S has probably depreciated by about $50k but you likely had free Supercharging so the net cost may have been close to that of a Camry/Civic. Not bad for an environmentally conscious luxury car that generates higher Uber profits.
 
Tesla’s warranty tells us what we can expect for degradation with at least one data point, 8 years and varying miles. For all models the warranty applies when degradation is below 70%. The Model S and X at 150,000 miles, Model 3 RWD at 100,000 miles and Model Y and Model 3 LR and P at 120,000 miles. When Tesla does come out with a million mile battery I wonder if the warranty will be updated.
 
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Tesla’s warranty tells us what we can expect for degradation with at least one data point, 8 years and varying miles. For all models the warranty applies when degradation is below 70%. The Model S and X at 150,000 miles, Model 3 RWD at 100,000 miles and Model Y and Model 3 LR and P at 120,000 miles. When Tesla does come out with a million mile battery I wonder if the warranty will be updated.

Not sure when they changed it but the model S and x did not use to have any guarantee of capacity. That is to say as long as the battery was working it could be down to 10% and you still couldn't ask for a warranty replacement. In practice, of course, they've never let that happen. But, there is no guarantee at all on our older cars as to battery pack capacity.
 

thesmokingman

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Jun 21, 2021
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As a single data point I'm just shy of 248,000 mi on my December 2014 model S. It has been supercharged two to three times a day, run to zero at least a half a dozen times, charged to 100% 100s of times. It's still on the original battery. I think Tesla's BMS is pretty robust. And no, you can't actually run it to zero. Just because it says zero on your screen doesn't mean Tesla didn't reserve a bit. I'm still a year out on my warranty so, hoping! But, I'll probably keep the car either way.
Concur. My aunt has an early S and they are over well over 200K miles. That car is commuted every day and basically lives off supercharging. She was thinking of getting a new one but the old one just won't die, so shrugs...
 
With so many factors determining battery life, imagine it will be difficult to predice your unique batteries life. Same thing with ICE motors.

Pretty much. Except that it's really, really, easy to destroy an ice engine. Just don't change the oil! Or rod it too hard, etc. With the Tesla's it's pretty hard to ruin the battery. You'd have to leave it at almost zero or almost all the way charged pretty regularly.
 
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We have the 2018 Tesla MS 100D and it has been reliable until a few days ago. I was driving from San Francisco to San Diego. I stopped near Bakersfield to charge the car to about 270 miles. We started down freeway 5 and I got a warning that I needed to charge the car and to pull over to the side of the road. I was lucky we were not hit by other traffic as it was about ten am. We had to wait for about two hours for Geico to send us a tow truck. Tesla in Bakersfield told us that the main battery needed to be replaced. Worse case it may take seven weeks to get it done. The battery is still under warranty so that helps. They provided a model 3 to continue our trip home. I had to learn how to drive this M3 as it does not operate like the MS does. I have to say it rides ok, but I like my MS. Tesla Workers at the Bakersfield location are very nice. Our Model S did not give us any indication in the days leading up to this battery failure. Has anyone else had something like this happen to them? Are the batteries installed in the newer cars better?
 
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So the consensus seems to be that its about age and not miles, but degradation happens due to heat generated.

The new 4680 batteries produce less heat, so they should last much longer than current batteries right?
Tesla batteries, like most EV's are liquid cooled. So unless the vehicle is in Arizona, and it's allowed to heat soak for long periods of time, I don't see this being an issue. I don't know if Telsas do the same, but the Volt will even cool the battery when needed even when it's not plugged in, provided an adequate charge level is present. The thermal management system also runs to cool the battery when it's plugged in.

I see batteries failing from infant mortality (manufacturing defects) or age. Heat and cycles shouldn't be an issue for most, provided you plug in at home as normal.
 
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So the consensus seems to be that its about age and not miles, but degradation happens due to heat generated.

The new 4680 batteries produce less heat, so they should last much longer than current batteries right?
The above is pretty much irrelevant to the problem @Sunray mentioned:

We have the 2018 Tesla MS 100D and it has been reliable until a few days ago. I was driving from San Francisco to San Diego. I stopped near Bakersfield to charge the car to about 270 miles. We started down freeway 5 and I got a warning that I needed to charge the car and to pull over to the side of the road. I was lucky we were not hit by other traffic as it was about ten am. We had to wait for about two hours for Geico to send us a tow truck. Tesla in Bakersfield told us that the main battery needed to be replaced. Worse case it may take seven weeks to get it done. The battery is still under warranty so that helps. They provided a model 3 to continue our trip home. I had to learn how to drive this M3 as it does not operate like the MS does. I have to say it rides ok, but I like my MS. Tesla Workers at the Bakersfield location are very nice. Our Model S did not give us any indication in the days leading up to this battery failure. Has anyone else had something like this happen to them? Are the batteries installed in the newer cars better?
This failure happened fast, age, heat, or mileage (charge-cycle) based degradation would reduce range over time, not suddenly give out on a 4 year old car.
@Sunray experienced some sort of unusual breakage in the battery. It is not common with old or new cars but, it does happen occasionally as do mechanical breakdowns with any car or device.
 
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Sandy Monroe stated that the 4680 will last a gazillion years, and he would know.

Plus, in the video showing off the 4680, tesla played a lyric in the background “i will go a million miles” Seems pretty reasonable to assume that 4680 batteries will last many many decades and for a million miles due to improved heat discharge.

Can anyone tell me why I am wrong to think this?
 

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