Researched Data: How Long Should A Tesla Battery Last?

SEP 13 2018 BY STEVEN LOVEDAY 31

Let’s take an up-close look at Tesla battery life, with analysis from a long list of owners’ cars.

Not long ago, we shared our friend Sean Mitchell’s video about having to replace the 60-kWh battery in his Tesla Model S. He shared what caused his battery’s rapid degradation so that other Tesla owners will make more informed choices. When all of this happened, it piqued his interest in Tesla batteries and how long they should last, etc. Because of this, Sean felt compelled to do some research.

Last week, Sean published his first video in the series “How long will a Tesla battery pack last?” We didn’t share it right away since it was essentially preliminary information stating that he’d found some valuable sources surrounding Tesla owners’ battery life and he intended to put together a more in-depth analysis of his findings. The above video is the culmination of Sean’s hard work. At the bottom of this article, we’ve embedded the previous video for your enjoyment. Kudos to Sean for including screenshots and shares from InsideEVs’ contributor George Bower and Keith Ritter in his analysis.

Sean told us that “failure is surprisingly low (2.24%) and overwhelmingly isolated to the 85 kWh battery and before 50K miles.” Based on what we’ve learned from George, it seems the Model 3 battery packs should fare even better.

Have you had any issues with your Tesla battery? How long have you owned the car and how much has the battery degraded? Share your information with us in the comment section below.

Video Description via Sean Mitchell on YouTube:

How long will a Tesla battery pack last? Pt 2

How long will a Tesla battery pack last? Pt 1: https://www.youtube.com/watch?v=6KPPTdYdpBM(Embedded below)

Battery degradation shared by owners: https://docs.google.com/spreadsheets/…


Video Description via Sean Mitchell on YouTube:

How long will a Tesla battery pack last? Pt 1

Tesla Model 3 Battery Cooling Much-Improved … Track Mode?: https://insideevs.com/tesla-model-3-b…

Categories: Battery Tech, Tesla, Videos

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31 Comments on "Researched Data: How Long Should A Tesla Battery Last?"

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Another Euro point of view

Interesting video. Thanks.

Viking79

Bad data. (it needs some processing before blindly looking at it)

3 of the battery failures are the same user with the same mileage of the failure so they represent only a single failure. This represents 50% of the failures. It looks like 3 different entries over time when survey was conducted as each time the total mileage goes up.

Did the video address this?

Viking79

Looks like out of 132 Unique cars, 4 had failures (3%). All were 85 kWh, 2 were D other 2 were P models. Average miles at failure was about 22,500. These are definitely not capacity loss, probably quality control, but need to monitor. Average car mileage in report is about 32,500. Given this is a self selecting survey I will assume the actual failure rate would be much less than this.

Will

3LR delivered end of June, with about 3,000km now, with most of my charging from 20% to 80%. 1st charge to 100% I got 509km. 2nd charge to 100% I got 504km. 3rd charge to 100% recently I got 496km. I’m moderately concerned this trend will continue. I’m not going to charge past 95% anymore, not even for long trips.

theflew

If the range is calculated like the Volt/Bolt EV then it will calculate the total range based on your energy usage. So the battery capacity has changed just the energy usage it uses to calculate the range.

CCIE

For better or worse, Tesla doesn’t adjust it’s range calculations like GM does. The system takes the usable kwh in the battery and divides by 240 wh/mi. In reality the RWD M3 with aero wheel covers is more efficient than that in most circumstances.

Example: The car thinks the battery has 75kwh of usable energy, so 75/0.24=312 miles range.

Joel B

Instead of seeing the (estimated?) range, is it possible to see the kWh storage or voltages?

Pushmi-Pullyu

No. No EV maker designs their cars to display that data. That’s why it’s almost impossible for anyone — even an expert — to accurately measure the actual kWh capacity (or capacity loss) of their EV’s battery pack.

Viking79

A sample of 3 charges is not statistically relevant. 3000 km only represents about 6 full charge cycles. My Volt would get 15 miles AER one charge, then 6 months later it would suddenly get 50 mile AER. Temperature. Too many variables.

Alex

It seems that variation is not related with battery condition but rather with road, driving . Relax :).

Unplugged

First – Yes, it’s a good idea to keep charging below 100% at all times. With the range of the 3LR, it really doesn’t make much difference whether you start at 90% versus 100%. Superchargers are usually spaced out to easily allow 80% to 90% charges. Second – It’s really hard to figure battery degradation based on estimated range. I use TeslaFi, and my range graph goes up and down depending upon kW used. (My 130 mph run didn’t help my range estimate.)

According to TeslaFi, my range began two months ago (my 3 is five months old) at 314.2, and now is down to about 310. But I attribute most of that 1% range loss to increasing my freeway speeds and driving less around town.

You would have to do a control test and then a later test over the same road, with the same temperature and wind at the same speed in order to come to a more accurate estimate of range.

Rusty

Lion chemistry shows more rapid degradation in the first 50000 miles of about 5%.
Thereafter flattens to around 1% per year.
https://electrek.co/2016/11/01/tesla-battery-degradation/

Doggydogworld

I wonder how many of these failures were contactors vs. cell/module? Contactor failures aren’t important, IMHO, but so many cell/module failures before 80k would be troubling.

Tesloop’s 400k mile Model S had its battery replaced twice. Neither was a simple contactor failure, Also, they recently talked about their Model X named “Rex” hitting 300k on the original battery. Odd they didn’t list Rex but did list “Deuxy” which has the same mileage. Perhaps Rex and Deuxy are the same car?

F150 Brian

Hopefully the Model 3 fares better than the S’s in that video, because that’s way too many battery/motor replacements.

To me, the better question to ask is what options will exist after the warranty is up. Is the car/pack designed to accept replacement batteries using better battery tech (more range, faster charging, lighter, etc).

If the answer to the above question is “like replacement”, then I would hope for a failure every 7 years (assuming 8 year warranty) so that I could get 14 years out of the car without paying for a replacement pack 😉

John Hollenberg

Meaningless analysis as sample was self selected. Would need a random selection to get data rather than anecdote.

Viking79

Not meaningless, but have to understand that it has a bias to the data. Organisations like Consumer Reports have similar self selected surveys.

John Hollenberg

True, but for Consumer Reports the key issue is the relative rates of defects reported for different cars, thus making the absolute level less important in selecting a vehicle to purchase. Also, they have a much larger sample size. My guess is that the actual failure rate is at least one order of magnitude less. There is no way 5.6% is the failure rate or Tesla would rank up there with Nissan’s battery capacity debacle.

Viking79

If you look at Google Docs spreadsheet, 3 of the 7 failures are the same failure, and also multiple reports there for each user. The data definitely needs some adjustment before use. I didn’t watch the video to see if that was done or not.

Counterpoint

Interesting. I have a Prius, and failure rates of 2nd & 3rd generation NiMH Prius drive batteries are extremely low (a Toyota exec was quoted as saying 1 in 40,000) for approximately the first 10 years, after which it increases to approximately 3%. To hear that the Model S has a battery failure rate of 5.6% over the first 80,000 miles driven would seem to imply that this failure rate would increase over time if the batteries are failing due to common wear. However, the other option is that the batteries that failed were poor quality or factory outliers from the beginning. If the second option is true, then more recent Teslas should have lower failure rates as they improve their quality control procedures. So while 5.6% is a comparatively small number, it’s important to keep monitoring this statistic to determine if it increases with vehicle age or decreases with newer models (or both).

Alex

I don’t know the details, but Prius usage of battery is very conservative. It’s like they use the battery between 30 and 70% of a usage in a mobile phone or pure electric car. I think that can explain part of the reliability they have.

Viking79

3 of the reports are the same battery failure, so statistics are off already (the same failure was reported 3 different times).

Alex

Liion batteries should last (conservative) for 1000 cycles keeping 80% of the capacity, that’s like 300K miles – more than the typical life of a car. If temperature is kept within limits. I suppose temperature outside good limits is the “best” enemy of liion batteries.

That’s the theory, cars with temperature active management seem to do a good job, but in phones (and I think they are much more radical with batteries) after 2 or 3 years or less it’s normal to see a severe decrease in capacity – sometimes 50% or less.

For a home project I would use lead acid batteries (blaspheme), because I think liion are still less reliable, if everything goes well, they will worth the extra up front cost but if something goes bad (like in Sean’s car) they can become a bad deal and offer a higher risk. But as car makers all (or close) insure batteries that’s a non problem.

Speculawyer

That’s a weird view for a home project, IMHO. Li-Ion batteries very reliable now. Yes, there is a chance they go bad…but with lead-acid, you KNOW they will go bad since they have shorter lifespans. So while you *might* have a problem with li-Ion, you KNOW you will have a problem with lead-acid in a few years. Plus there’s that releasing of hydrogen gas issue.

Alex

For some cases lead acid batteries are not a bad idea. If you look careful price of liion batteries can be 4 times higher – and I’m not considering cheap low cycles batteries.
Liion batteries should have a longer life but warranties offered don’t always follow at the same rate that greater expected life.
Hot climates are more troublesome for liion, Tesla per example offer less capacity warranty for some countries.

It’s true that in an application where deep cycling is very frequently liion is just the only way to go, but those requirements are not always the case.

Pushmi-Pullyu

Yeah, nobody who is serious about an EV conversion uses lead-acid batteries any more. It was several years ago that the rule of thumb was that if you have to replace the deep-cycle lead-acid batteries twice, you were better off starting with li-ion in the first place, just on price.

These days li-ion batteries are even cheaper, so there’s no way to justify using lead-acid instead, assuming you’re planning on driving the car for at least a few years.

Jason

Someone should tell the fuel cell crowd. Surprised they haven’t proposed “drive on Lead Acid batteries, and capture the hydrogen to use in the fuel cell”.

Speculawyer

Remember how the haters used to always say “Durrr…you’re gonna have to replace your battery in 3 to 4 years”? Glad those days are mostly gone. Actually, I still do run across such posts now & then. EV batteries have proved reliable over the long term. Especially when they have a thermal management system.

Jason

Yep, that’s right, had to replace those damn Leaf batteries twice now…Wait… That’s not right…Nope, never had to replace them yet!

James Reno

I had a Model S 85 built in mid 2014. In June of 2016 a service warning popped up on the dash display. When I called Tesla they informed me that engineers in California had detected intermittent issues in my HV battery. I had experienced no symptoms and we travelled a lot and had about 55k miles on the car. Most miles using Superchargers. I took the car to a service center in Ohio since we were traveling at the time. They gave me a loaner for the day. They replaced our HV battery with a loaner and shipped our battery pack to California for inspection and repair. We put about 5000 miles on their loaner pack. Two months later they shipped our pack to our service center in Florida and we again got a loaner for the day while they swapped packs. We sold the car in 2018 with 117,000 miles on it. We never experienced any battery issues in the time we drove the car. Full charge at the time we sold it was about 250 range miles.

Alex

In two years 90% charged pack on my car went from showing 242 miles to 216 -(25000 miles, mostly L2 charging)