What you need to consider is that the battery is either correctly manufactured or it is manufactured with a fault. If it is manufactured with a fault then it normally rears its head not too long after purchase, like yours did, and well within the warranty period. Batteries that run without issue for years, right through to the end of the warranty, are unlikely to have a manufacturing fault. The only thing left to worry about being any degradation from the number of charge cycles. Current evidence suggests though that this is not turning out to be a significant issue and therefore buying a used EV that has also run for several years without manifesting a battery fault is probably a safe used purchase. Just my thoughts on the matter.

 

Batteries are composed of dozens of prismatic or thousands of cylindric cells and any one or more cells failing over a period of time has its own probability.

When you are talking about thousands of cylindric cells, the failure probability is not that low as it is the sum of all failure probabilities. In a 5000 cell battery pack with a 5 year cell failure probability of 0.02%, the 5-year failure probability at the pack level is 100%. This is why it's becoming a norm to see "just got a new pack under warranty" in used BEV adverts. But nobody wants to talk about the CO2 impact of battery pack failures...

The million mile Tesla Model S was on its 4th battery when it reached a million miles, so in that case the million mile battery failure rate was 300%.

Even perfectly manufactured batteries can fail at any given moment, it's the nature of the product.

An older battery is generally more likely to fail than a new one. In most cases current battery cells do not last longer than 20 years, so the 20 year failure rate can be considered to be 100%.

Some are talking about 18650 failure rates of 1 in x million but that is nonsense and non-scientific as failure rates should be a function of time, cycles and other parameters of use.

Some like Tesla are even embarking into structural batteries, it's a suicide mission.

 

On June 15, 2022 (Europe time), he expects to pass the one million mile mark, and to have it officially recognised by the prestigious Guinness Book of Records.
All this on three batteries replaced under warranty, the last of which has done 400,000km.

Tesla Model S owner passes incredible one million mile mark, but may switch to Lucid

Hansjörg Gemmingen reaches another remarkable milestone in his Tesla Model S, but is considering changing to a Lucid Air.

thedriven.io

Tesla PR Xinix is accusing of lies when his own quoted article is confirming the car had 3 batteries replaced.
Don't trust his lies.

Also, battery failure rates have nothing to do with battery degradation, those are parallel subjects.
Battery degradation can also be hidden by how you program the BMS.
The 30kWh Nissan Leaf is evidence of this as its BMS was wrongly programmed to show a larger degradation than it really underwent, hence requiring a software update to rectify this.
As this software update proves, the BMS can be programmed to show a larger degradation and then tweaked to show a smaller degradation, the only way to measure real degradation is to compare a new cell with a used cell on a test bank.

 

On June 15, 2022 (Europe time), he expects to pass the one million mile mark, and to have it officially recognised by the prestigious Guinness Book of Records.
All this on three batteries replaced under warranty, the last of which has done 400,000km.

Tesla Model S owner passes incredible one million mile mark, but may switch to Lucid

Hansjörg Gemmingen reaches another remarkable milestone in his Tesla Model S, but is considering changing to a Lucid Air.

thedriven.io

Tesla PR Xinix is accusing of lies when his own quoted article is confirming the car had 3 batteries replaced.
Don't trust his lies.

Also, battery failure rates have nothing to do with battery degradation, those are parallel subjects.
Battery degradation can also be hidden by how you program the BMS.
The 30kWh Nissan Leaf is evidence of this as its BMS was wrongly programmed to show a larger degradation than it really underwent, hence requiring a software update to rectify this.
As this software update proves, the BMS can be programmed to show a larger degradation and then tweaked to show a smaller degradation, the only way to measure real degradation is to compare a new cell with a used cell on a test bank.

You really are being an obnoxious persona on this forum. You spill all kind of drivel of how Hydrogen is the future and BEV doesn't cut it when all evidence is just showing you are wrong on both accounts. How's that cognitive dissonance of yours doing?

Tesla PR Xinix??? LOL... You really have no idea do you? FYI: I drive an e-Niro so that's one blooper.

Second: please make sure you know what you're writing about. Which article did I quote? The one that says this?

He is also currently on his third battery pack, a 63.1kWh pack that has about 310km (193mi) of range on a full charge after driving it for about 400,000km (248,000mi).

Let me explain: his third battery pack means it was replaced twice.

And please don't give the 30 kWh Leaf as an example of battery degradation. Instead, since you are the one arguing this: show me numbers that prove there's a significant percentage of battery packs that show premature failure in cars built after 2015. Hint: you won't be able to since they don't.

 

Very few EV's have reached the end of their battery warranty yet so there is a very limited pool of data to draw any conclusions from. I'm running my Ampera battery out of warranty but i'm not concerned by that it's serious ly understressed with only 66% of it's capacity being used. Compared to 90% for most more modern EV's.
Number of cycles to failure is really dificult to predict as there are so many variables in general I don't think I would run a structural battery beyond warranty but it would depend on the warrany in California to qualify as ULEZ compliant one of the criteria is 15 years or 150,000 miles design life and we are seeing high milage Volt and Amperas with more that 100K miles and 12 years on the road.

 

Battery failures are not as rare as you think.
They are frequent enough that owning an out of warranty BEV entails a serious financial risk.

"New reconditioned battery in Dec 2022" Auto Trader UK - New and Used Cars For Sale
"New 90Kw main battery installed by Tesla Dec 2022 (less than 4K miles since) " Auto Trader UK - New and Used Cars For Sale
"New battery from last year with 30k miles ." Auto Trader UK - New and Used Cars For Sale
Full New Battery Installed recently by Tesla Auto Trader UK - New and Used Cars For Sale

 

Au contraire... seems they are even more rare than I thought. I asked you to show me numbers that prove there's a significant percentage of battery packs with premature failures. And you end up with 4 cases. All of them Tesla Model S, and 3 of them P85s. P85 packs are indeed known for having problems more than average and that's why Tesla have been quite lenient in replacing them.

Anyway, if that's all you can come up with, then please go away. You have zero arguments that batteries have high failure rates.

Incidentally, I agree with your view that structural batteries are an aberration. They go fully against the 'right to repair' so should be forbidden. Just to show I am no Tesla PR boy

 

This post could have the words ‘HV Battery’ replaced with ‘engine’ and I could take you to dozens of threads on BMW, Mercedes, Audi forums where £10K-£25K entire engines, gearboxes or parts thereof have been replaced under warranty (a 3 year warranty in most cases) and all similarly delayed by the pandemic. Expensive parts go wrong on expensive cars. That’s what warranties are for. You’re at least smart enough to have bought a car with a 5-year unlimited mileage warranty and an 8-year battery warranty. In straight comparison terms there is very to little fail on an electric motor and inverter so people focus on the battery. Main dealer prices (especially warranty claim prices) are, and always will be, daft compared to an independent so get yourself a quote for a part or full battery swap from a HEVRA garage and it will be significantly less.

And I would much rather buy a used EV than a used ICE car just because of the complexity of the oily bits and the ease whereby you can shorten the life of an internal combustion engine by taking it on short trips, ragging it when cold, not running it in properly etc.

 

This post could have the words ‘HV Battery’ replaced with ‘engine’ and I could take you to dozens of threads on BMW, Mercedes, Audi forums where £10K-£25K entire engines, gearboxes or parts thereof have been replaced under warranty (a 3 year warranty in most cases) and all similarly delayed by the pandemic.

I agree. My Chevrolet Volt had its main battery replaced (under warranty) when it was about a year old. A few years earlier than that my wife's Mazda 3 had the engine replaced (also under warranty). So as a family we're one all.

These things are much more likely to happen when new for several reasons, not just that if there's a faulty part when manufacturing it will go sooner rather than later but also when there's a warranty they're much more likely just to switch out the whole unit rather than spending time trying to diagnose the actual problem. I expect with the Volt's battery they could probably have switched much less than the whole battery if they had the time and expertise. The Mazda's engine was a melted lump though so that was definitely a full replacement needed (and extra delay because there were more melted bits under the engine).

 

This is not a cheap fix, and had the battery being just out of warranty, would have had a catastrophic affect on personal finances. Will I keep it beyond the warranty period? No. Would I consider buying a used electric vehicle with no battery warranty? Probably not, unless the price was amazing.

Thoughts?

It sounds like there was an initial failure to diagnose the problem and either incorrect, or insufficient parts replaced. Because we don’t know what was actually wrong with the battery system it’s hard to say, but my suspicion is this was a parts canon repair. What I would expect is that by the time these cars are completely out of warranty there will be sufficient interest from third parties to be able to diagnose faults and provide cost effective repairs.

After all the battery we’re talking about is a modular thing with a lot of cells, various bits of BMS, contactors, comms units…. The failure of any of those components would result in the failure of a battery.

There’s a great example from the I-miev of the BMS failing - a very expensive repair that almost certainly led to some cars being scrapped. The actual component failure is a particular chip that’s cheap and can be replaced. This fault can be a very cost effective repair but only when done by a third party.

 

It sounds like there was an initial failure to diagnose the problem and either incorrect, or insufficient parts replaced. Because we don’t know what was actually wrong with the battery system it’s hard to say, but my suspicion is this was a parts canon repair. What I would expect is that by the time these cars are completely out of warranty there will be sufficient interest from third parties to be able to diagnose faults and provide cost effective repairs.

After all the battery we’re talking about is a modular thing with a lot of cells, various bits of BMS, contactors, comms units…. The failure of any of those components would result in the failure of a battery.

There’s a great example from the I-miev of the BMS failing - a very expensive repair that almost certainly led to some cars being scrapped. The actual component failure is a particular chip that’s cheap and can be replaced. This fault can be a very cost effective repair but only when done by a third party.

Third parties have limitations as OEM's are intentionally making it hard to decode their hardware.

Everyone said something similar to you about the Leaf, which is built in larger numbers than the Kona will ever be.
Yet it's very hard for third parties to get around the obstacles set by Nissan.

This post could have the words ‘HV Battery’ replaced with ‘engine’ and I could take you to dozens of threads on BMW, Mercedes, Audi forums where £10K-£25K entire engines, gearboxes or parts thereof have been replaced under warranty (a 3 year warranty in most cases) and all similarly delayed by the pandemic. Expensive parts go wrong on expensive cars. That’s what warranties are for. You’re at least smart enough to have bought a car with a 5-year unlimited mileage warranty and an 8-year battery warranty. In straight comparison terms there is very to little fail on an electric motor and inverter so people focus on the battery. Main dealer prices (especially warranty claim prices) are, and always will be, daft compared to an independent so get yourself a quote for a part or full battery swap from a HEVRA garage and it will be significantly less.

And I would much rather buy a used EV than a used ICE car just because of the complexity of the oily bits and the ease whereby you can shorten the life of an internal combustion engine by taking it on short trips, ragging it when cold, not running it in properly etc.

It's out of warranty that things diverge significantly.
An out of warranty ICE will have scrapyards full of parts and myriads of garages with the skills to do the repairs, while an out of warranty BEV will struggle with both those elements.

Take for example someone like Dala, who is the top authority on BEV DIY's and mods, even for him things are not straightforward.
I suggest you watch the following video's.

 

@stageshoot is the definitive authority on this - to spare him the pain of reliving the experience, search out his posts on the forum which document the high mileage Kona sagas he has enjoyed / endured.