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Comment by pengaru | Hacker News Reader

I fully expect grid energy storage to be where used BEV batteries spend the end of their usable life before getting recycled.

It'd just be nice if the manufacturers would establish some vendor-neutral standards already, paving the way for this future. I hate the idea of buying a BEV with a proprietary battery of such obvious long-term value beyond my vehicle's needs, especially when it forms such a huge portion of the vehicle's cost. At this point I'm half assuming I'll need to DIY a powerwall out back when the time comes to replace my future BEV's battery.

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> It'd just be nice if the manufacturers would establish some vendor-neutral standards already, paving the way for this future.

I don’t think we’ll ever see this happen. Being able to tweak battery chemistry to suite different vehicles is just too valuable. I imagine at some point different manufacturers will start touting their specific magic battery sauce as being a reason to buy their cars over a competitor. Not to mention the onward march of incrementally better battery chemistries.

But equally the fundamentals of the battery chemistry don’t change that much, and in a recycling scenario where you don’t need to squeeze every last electron into, or out of the battery. You can probably throw a very generic battery management circuit over the top and call it a day.

As for the physical form factor. Again I suspect this will always be different for different cars. But equally, if you can find the positive contact and the negative contact, then the physical form factor doesn’t matter much.

So at the end of day, we probably won’t see much standardisation. But equally it’s probably not that important if you’re recycling. Fundamentally all the batteries will be electrically similar enough it won’t really matter.

None of that prevents them from establishing a standard size and connector type and a standard format for communicating properties of the batteries. NiCd batteries come in all kinds of minor configurations but as long as you know the basic chemistry and voltage you can use a cheap charger to charge them. Even if we hit a period of explosive experimentation with geometry (conical batteries, sheet batteries, string batteries, string batteries wound into comical coils made into slabs), we will eventually have a few specific form factors and that matters more to reusing these than the exact chemical composition.

Imagine if you had to buy Ford branded gasoline because that was slightly more efficient in Ford vehicles and therefore couldn’t be used in Toyotas. That’s effectively what you are advocating.

I think in a recycling scenario you’re gonna be stripping these batteries down to their cells anyway, so their physical format is kinda irrelevant.

As for their properties, you’re almost certainly better of just measuring them, rather than relying on some sort of digital spec sheet. You’ll have no idea what life these batteries have led, and thus no idea how much they’ve drifted from their spec sheet.

The battery chemistry pretty much determines all their important characteristics such as voltage, and charge/discharge pattens. There’s a very limited number of fundamental battery chemistries to pick from, and you can almost certainly ignore the secret source car manufactures are using. You just end up running the batteries slightly less efficiently, but again their at the end of their automotive life, which is the bit when people actually care about peak efficiency.

As for you analogy, it’s a bit more like wheels and tires on a car. There are hundreds of different tire treads, and plenty of different wheel sizes. But if you’re recycling a wheel or tire, you almost certainly don’t care much about either it’s size or tire tread, because it’s trivial to build a recycling process that can handle almost any type of wheel or tire.

They form a huge portion of the vehicle’s cost today, but battery prices have been dropping 21% a year. Assuming the pack in the car lasts 10 years, by then a new pack would cost just 10% of the one put in the car. At that point is it even worth reconditioning, adapting and reusing over recycling?

I didn't mean cost strictly in the monetary sense.

The battery in a BEV accounts for a substantial portion of the resources involved in its manufacture. The battery forms basically half the mass of the entire vehicle, and we're not talking about a sack of unprocessed dirt here. If it has usable life left for energy storage purposes as-is, we should absolutely take advantage of it.

The decision on whether to reuse or recycle should be informed by lifecycle analyses of the costs and externalities of both options. Maintenance isn't free of externalities and it will presumably be much higher in a system made up of older batteries. The opportunity costs shouldn't be entirely dismissed either - lower hanging fruit for removing emissions may be available elsewhere.

For Tesla's the battery pack is about 1/4 of the vehicle's weight. The battery pack weighs around 500Kg and the car is around 2,000Kg, depending on the model. The main problem as EV manufacturers look to shave weight the batteries are going to become more integrated into the car's structure, which is going to make them harder to remove and reuse the cells at the end of the car's life.

Do you have any examples of designs where batteries are literally integrated into vehicle structure?

The iconic Tesla battery-skate design is still modular/replaceable for example (they're all 18650/2170/etc cells).

Individual cells might in theory be modular, but Tesla for example is gluing them to their battery packs which makes them much harder to reuse at the individual cell levels. The battery pack it’s self is becoming a structural element though it can still be removed, but unfortunately it’s proprietary.

On top of this EV batteries are getting very close to lasting the normal lifetime of the vehicle. Car manufacturers are likely to tray and leverage this as a form of built in obsolescence by making replacing the battery unappealing under normal usage patterns.

Here's some pictures of Tesla's plans for it's battery pack:

https://electrek.co/2021/01/19/tesla-structural-battery-pack...

In that article it specifically mentions the cells being "bound" (their words not mine) into the honeycomb pack.

> The main problem as EV manufacturers look to shave weight the batteries are going to become more integrated into the car's structure

For those looking for a source, here's Elon Musk saying exactly that to Sandy Munro.

https://youtu.be/YAtLTLiqNwg?t=1335

I feel like it's unlikely for pack prices to continue to drop 21%/year. Tesla+Panasonic have gotten pretty good at reducing pack costs, and while Tesla's in-house cells could reduce costs significantly, IIRC, a 21%/year reduction in costs for a decade would be significantly less than the materials cost.

I watched this last week and was blown away at how useful "used" cells could be in the right hands. Also, imagining what low skill labor looks like a battery offset world.

https://www.youtube.com/watch?v=PenPYwa00CA

My understanding is that used laptop batteries are particularly good for this sort of thing, because what happens is that one cell (out of six or nine) dies and the laptop battery becomes unusable since they are wired in series, and then you have five (or eight) used but relatively healthy cells to reuse.

I am not sure whether the same idea could be applied to a car battery with much more advanced battery management systems, since in those situations dead cells don't cripple the battery, so the other cells keep getting used until they lose efficacy. So I suspect cells scavenged from car batteries will be of lesser quality than those scavenged from laptops.

Not totally sure if I have it right.

I'm imagining for a more advanced BMS system that manages dead cells for you, you don't scavenge cells but instead use the battery pack as a whole unit, just separated from the car.

Think something like a conversion kit that turns your Model 3 battery pack that you've removed from your car into a powerwall.

People on the DIY solar forum already use old Tesla batteries for powerwalls so there’s likely to be kits in the future to make it plug and play.

Not sure about EVs, but replacing single dead cells is common on hybrid vehicles. It's pretty common for them to be series'd up as well.

The power plant operators do not agree, currently. the energy storage margin is thin and li-ion lifetime too short already... if you refer to grid scale. Look at the APS battery 'event' and the hazard to emergency response personnel batteries pose as a grid asset. Some form of home hybrid using recycled batteries may work, but the safety expertise and market payback don't work except at the DIY scale... Maybe it's a biz opportunity.

That sounds right. What utilities want are components that you install and thereafter take little attention. Re-using recycled batteries does not fit that model. They'd be much happier with something that cost more but lasted 20-30 years.

It's not even really a question of attention so much as maintenance. Fixed up front costs are easy to handle as capital that can go into their rate cases, but more so power equipment lifetime is measured in decades and the discharge lifecycles of available battery technology is already not great for an installation expected to go to near full discharge on a regular basis.

If the planned usage is only a 10% semi-daily scenario for stability support that may result in 5-10 years longer lifetimes versus daily discharges for capacity shifting.

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