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Comment by cgyvbunji | Hacker News Reader

They still die by calendar age based degradation. High miles low years isn't interesting. We know that works well. They don't like talking about the calendar age degradation. Every article like this leaves that part out. It's annoying. Many articles have been written like this. Many more will be written yet. I guess there are still people out there who don't know that EVs are ideal for drivers who accumulate high miles per year. Personally I don't think batteries are going to get interesting until solid state batteries. The problem is the electrolyte.

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Do you have more information regarding age based degradation? I haven't looked too deeply into the topic and I am not sure if the argument had been about pure age based degradation or about "after X years because a person will have driven Y kilometers since then".

False

"A 2015 Model S with over 265,000 miles on the original battery (85% capacity remaining)"

That's 25000 miles per year, which is high. So the opposite of false.

The comment above is (I would guess) about the eleven years of original battery usage rather than the mileage.

The implication being that runs counter to the claim of "calendar age degradation".

Do you mean 11 years is a "long" time? I'd say it doesn't matter how long it was - it ended up better the expected based on the miles, and since it was a high-mileage-per-year car, that supports the claim that degradation is determined (at least more than expected) by calendar years, as cgyv.. claimed. I don't see how it doesn't support his claim.

It's all moot speculation in the absence of any firm notation of what cgyvbunji considers "calendar age based degradation" to be.

The battery industry defines calendar age degradation, not a random guy on the Internet like me. It's like saying you can't discuss voltage without me defining what voltage is.

So according to you, the more you degrade the battery, the longer it lasts?

Usually you would think that 25000 miles per year over 11 years would degrade the battery faster than the car just sitting around for 11 years.

According to cygv... the more intensely you use the battery, the more miles you get out of it, so kind of yea, the faster you use it, the "longer" it lasts in miles. And this example supports that idea because it was used more intensely than usual and lasted more miles than usual.

Yes, exactly, as long as you don't fast charge. The ideal scenario for TCO measured as dollars per mile driven should be driving every day until you are down to some threshold, slow charging overnight, and repeating that each day until it's a brick. Should end up with something like 200-300k miles that way.

OP said 'They still die by calendar age based degradation', they don't was my point. They degrade based on charge cycles.

My EV is also over ten years old and has no noticeable battery degradation. I'm sure there is some degradation that could be measured, but in daily driving, I have the same range I did the day I bought the car.

> They still die by calendar age based degradation

Source?

Not OP, but this talks about it: https://www.sciencedirect.com/science/article/pii/S2352152X2...

That article says calendar ageing was the dominant ageing mechanism for batteries in their test vehicle, because said vehicle spent 96% of its life stationary. Unless I'm missing it, the article doesn't put a number figure on the rate of calendar ageing.

Real-world observations suggest batteries are likely to be serviceable for around 20 years, which is around the same lifetime of an average ICE car. Users who can tolerate a much reduced range (which is most of us) can likely extend this even further.

It's not clear how much of a factor calendar age degradation is in EVs because almost nobody is straightforward about it like they are in the battery industry itself.

Lithium batteries age even just sitting on the shelf. I fly RC planes and we store our batteries at 3.8V to lengthen their life, but they still deteriorate even when not used. Like anything else, I guess.

The article specifically talks about how this has changed with the evolution of chemistry in Li based car batteries.

I suspect the RC plane batteries you've been using for five years are not the same chemically as the EV car batteries in use in the UK for five years.

I can't read the article, as it's paywalled, but they're all LiPo/Li-Ion batteries, what's the difference? Hell, most cars just use the same 18650 cells we use, just a lot more of them.

> but they're all LiPo/Li-Ion batteries, what's the difference?

As I mentioned, the article specifically mentions that the battery chemistry has been changed and improved.

It neglects to dive into the chemical engineering specifics of such changes, as would be expected for press such as the WSJ.

I dare say there is as much variation in the attributes of the LiPo/Li-Ion battery family as there is within the borosilicate glass or soda–lime glass families (ie heaps).

Sure, but why are you assuming RC planes don't use the chemistry improvements as they come out?

It’s a niche, small-volume market. I would be shocked if novel industrial battery chemistries are reaching it within even years of the frontier. (Less surprising would be small-batch novel chemistries. But these aren’t really comparable to the industrially-produced thing.)

We mostly use the same 18650 cells everyone else uses for everything, it's not like we're waiting for custom batteries.

Again, the article specifically talks about improvements in car battery life since changes were made to tweak the chemistry (very likely in small dope ways).

The fact that the article states that this appears to result in longer life and the fact that you talk about your RC plane batteries not having a longer life would suggest that the fine specifics of the two batteries may well differ.

IDK I rarely see 18650 cells in RC. It's mostly pouches which I assume come from smartphone/laptop industry - these are likely to have highest margins and highest tech (other than space).

Put them in the vegetable bin in the fridge, too. Should make them last much longer.

Can confirm, I bought some Panasonic cells roughly 10 years ago for a battery pack, and have ~12 cells that didn't make it into the pack.

They've been sitting unused, in their original packaging, never opened... They're still sitting at the charge they shipped at, but the capacity is so diminished that one can't even run an esp32 for a day. I've tried cycling them to see if I can get the capacity back up, but I think they're toast already.

Yeah, and those come at 3.8V (storage voltage) already, so it's not like they were sitting fully charged.

But these are not sitting on the shelf are they, they are in a car with all sorts of systems managing the battery (well Teslas do).

If this is true it's interesting, as ICE cars typically prefer to be driven continuously at operating temperatures, rather than cold. This is why a high-mileage low-year car can actually have an engine in much better condition than low-mileage high year cars.

This is just untrue.

It is not necessarily untrue (source: am currently involved in battery R&D). However, the degree to which it is true will vary strongly based on the particular choice of chemistry, what sort of additives/agents are used (e.g. scavengers/getters), cell/pack engineering choices (protection against ingress of outside atmosphere and such), and so on and so forth.

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