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Comment by dragontamer | Hacker News Reader

LFP is 3000 cycles last time I checked.

NCA, a very common LiIon chemistry, is only 500 cycles as the article rightfully claims

The article is anywhere from 'correct' to off by 600% depending on which LiIon chemistry. But that's the nature of such a wide chemistry, there's so many LiIon out there it's hard to generalize.

NCA / NMC is common for phone and even EV applications though. So it's not necessarily wrong and both have similar endurance specs.

> Anyway, the article carefully avoids talking about energy density. Which is of course the key thing here.

No one cares about density in utility scale applications. It can be heavy as all heck but as long as it's cheap it will be an effective solar or wind battery.

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You can't really generalize cycles based on chemistry alone. Battery management and usage matters. But two examples with NCA/NMC chemistry:

- The Tesla Powerwall 2 battery warranty[1] is for effectively 3650 cycles (daily cycle for 10 years).

- Many cases of Tesla cars at 200k mileage (~1000 cycles, depends on battery size) with less than 15% capacity loss[2].

And these batteries didn't die after reaching the high number of cycles, they just retained less capacity.

[1] https://energylibrary.tesla.com/docs/Public/EnergyStorage/Po...

[2] https://insideevs.com/news/723734/tesla-model-3y-battery-cap...

Yes, Your phone or laptop though... that we dont have regulations that at least require manufacturers to give users the option to not charge to 100% is beyond me.

Many billions of batteries and thus billions of devices needlessly scrapped.

FWIW, Apple's current batteries are stated to last 1000 cycles until they reach 80% capacity. [0]

Anecdotally I have 98% capacity at 248 cycles on my 15 pro. I use an 80% charge limit as I don't use that much battery in a day.

[0] https://9to5mac.com/2024/02/20/iphone-15-battery-lifescyle-s...

The 80% charge limit will dramatically extend the lifespan.

It turns out the top few percent is what really damages the cells - which means there is always an inherent capacity vs cycle life tradeoff.

Energy density indirectly matters in utility scale applications, since it implies the cost is more dependent on raw materials and therefore it limits how low the cost of production can get.

In contrast if the raw materials are dirt-cheap per watt-hour (because you don't require as much mass) but the manufacturing process is expensive, then over time the manufacturing process can generally be made cheaper and you can expect the batter to get cheaper quicker.

3000 for LFP is a common number, but there are some that are now claiming 6000 cycles. Of course like everyone has mentioned, battery management matters and charging temperature, discharge temperature, charge and discharge limits matter.

Also for utility uses, why is 80% the benchmark? It seems likely that batteries will be used down to 60% capacity; so double the number of cycles for a reduced capacity.

Also, in a utility-scale battery with literally millions of cells there will always be gradual but constant replacement of a small amount of cells, while the remaining cells continue to bear the load. This is something you can't do in a phone, and what may be too costly in a EV.

It doesn't quite work out for a centralized utility scale battery unless it gets built gradually over the expected lifetime of the component batteries, as most existing infrastructure projects tend to get financed and built all at once, so all the batteries are the same age and are likely to require replacement around the same time. On a small scale that is quite visible with UPS batteries in data centers that all fail at once.

The easiest way to avoid that is to slow things down and build up a decentralized grid scale battery over time through incentives.

A few companies are cropping up to do EV battery repairs so it may be affordable to a consumer.

E.g. https://cedarelectric.co.uk/electric-and-hybrid-battery-repa...

My thoughts are that even after 80% usage the battery still has a second life for use in home power storage. Even after that most of the battery parts can be recycled. I think that battery trade-in schemes will start to become affordable once these reuse and recycling routes are scaled up.

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