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Can “second life” EV batteries work as grid-scale energy storage?

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Re: Can “second life” EV batteries work as grid-scale energy storage?

#161

Post by formerly_proven »

kragen wrote: post #130
maxerickson wrote: post #100

Earlier quoted context omitted.

What's the proposed system design? For example, in January, I get about 9 hours of sunlight and have an average daily high of 25 F. I'm gonna need to store heat somehow or another.

I haven't seen pfdietz's proposed system design, but a so-called "sand battery," consisting of a box of sand with a heating element running through it, should work fine. You can PWM the heating element with a power MOSFET to keep it from overheating; you can measure its temperature with its own resistance, but also want additional thermocouple probes for the sand and to measure the surface of the box. A fan can blow…

Did you just reinvent electric night storage heaters?

Re: Can “second life” EV batteries work as grid-scale energy storage?

#162

Post by p0w3n3d »

stetrain wrote: post #30
p0w3n3d wrote: post #18

Earlier quoted context omitted.

Tesla batteries fail after 8 years at least from models up to 2014

The number of Teslas sold up to 2014 is less than 1% of all Teslas sold. Tesla has an 8-year battery and drivetrain warranty but they don't necessarily fail after that date.

there is an ubiquitous failure of Panasonic-created cells for Tesla. I made a research on forums, because I wanted one, and investigated why there is such a price drop. Cars getting close to the age of 8 years immediately drop on price to even 10k usd. It's because if you get your battery replaced on warranty - you won. Otherwise it often deteriorates suddenly.

Re: Can “second life” EV batteries work as grid-scale energy storage?

#163

Post by kragen »

formerly_proven wrote: post #161
kragen wrote: post #130

Earlier quoted context omitted.

I haven't seen pfdietz's proposed system design, but a so-called "sand battery," consisting of a box of sand with a heating element running through it, should work fine. You can PWM the heating element with a power MOSFET to keep it from overheating; you can measure its temperature with its own resistance, but also want additional thermocouple probes for the sand and to measure the surface of the box. A fan can blow…

Did you just reinvent electric night storage heaters?

I would instead say that, familiar with many designs from millennia of history of using thermal mass for indoor climate control, I outlined a design of an electric night storage heater that is especially cheap and convenient. Or an "electric day storage heater", I guess, since the day is when it stores heat.

Re: Can “second life” EV batteries work as grid-scale energy storage?

#164

Post by jwr »

bryanlarsen wrote: post #2

This is less useful than most people expected. Redwood has been struggling because the expected battery turnover is not occurring. EV batteries are lasting a long time, so they stay in the car are and not being recycled or reused in any quantity yet. If EV batteries last 20+ years in EV's, it'll be > 2040 before there are significant numbers of EV batteries available to recycle or reuse. https://www.geotab.com/blog/e…

> the expected battery turnover is not occurring

I find this somewhat amusing, because the black PR of the fossil-fuel industry would have us believe that EV batteries basically have a 2-year lifespan, cost lots of CO2 to produce, instantly become toxic waste after those 2 years, are non-recyclable, and overall as a result EVs emit more CO2 than gasoline-burning cars. We are being told that EVs have a larger CO2 footprint than gasoline-burners.

Then Redwood shows up with a perfect way to utilize all those discarded batteries without even opening them up, and… that toxic industrial junk isn't even there?

Re: Can “second life” EV batteries work as grid-scale energy storage?

#166

Post by formerly_proven »

numpad0 wrote: post #88
formerly_proven wrote: post #58

Earlier quoted context omitted.

EVs no, but I think some Toyota hybrids (which are of course not even PHEVs) still use NiMH. Toyota tends to be very tight-lipped about their batteries and their sizes (or rather, lack thereof).

Tends to be tight lipped??? It is in the catalog[1]! It is more that American consumers aren't tech obsessed than Toyota being reluctant to share. Even just looking at online media reports[2][3] clearly sourced from some exact same press event, it is obvious that US English equivalents are much lighter in content than Japanese versions. They're putting the information out, no one's reading it. It's just been the type…

Despite your ??? and ! the only article you posted that's about hybrids (and not PHEVs) mentions nothing about battery capacity.

Re: Can “second life” EV batteries work as grid-scale energy storage?

#167

Post by jillesvangurp »

dylan604 wrote: post #9

Without being a battery chemistry expert, why do these battery packs become not useful for an EV yet could still be useful for energy storage. They keep saying that 80% of life becomes unusable for EV, but that's still a lot of life. Is it that grid energy is more of a constant drain while the EV is lots of hard pulls (for lack of better wording)? In an EV, the battery cannot provide the higher volts being requested…

The load in an EV is very different than in storage. Basically the charge and discharge rate is what deteriorates the battery. EVs need a lot of power delivered quickly in bursts when you accelerate (tens/hundreds of kw). And then fast charging when the driver is in a hurry also puts a lot of stress on the battery. With storage solutions, the power requirements are much less intense. These high bursts of energy would actually blow the fuse in your house. They are simply not needed. And there is no need for fast charging them either. Instead they get charged over many hours when there is cheap power available.

Companies like Redwood are good at assessing the state of the battery and then managing it such that it is run optimally. Usually, it's just a few cells that are no longer working; the rest of the pack is still be fine. So that just means the max output of the pack drops a bit. But that's still more than fine for storage if all you need is a few kw of output.

Running the battery optimally also extends the useful life of the remaining cells.

Re: Can “second life” EV batteries work as grid-scale energy storage?

#168

Post by numpad0 »

rgmerk wrote: post #119
numpad0 wrote: post #93

Earlier quoted context omitted.

It's not like reliable gas cars ever had substantial maintenance problem in the gas part. So removing the gas part didn't do much in practice. People do/did have frustrations with gas car mannerisms and mental approachability, like, everything was written in a mix of translated foreign language documents and borderline insane gearhead languages. That lead them to imagine that removing the gas part would drastically c…

Reliable gas cars still require a lot more maintenance than an EV does. Oil and oil filter changes. Fuel filters. Air cleaners. Brake pads (that mostly goes away with hybrids too).

And this is what I'm referring to by approachability issues. Even HNers can't correctly enumerate maintenance items for a car.

If I said iPads are better than laptops because there's no need to regularly replace soft drive Window and repaste NPUs every 2000 hours, everyone knows what kind of person I would be. Yet, that just casually happen all the time when it comes to EVs.

Re: Can “second life” EV batteries work as grid-scale energy storage?

#169

Post by torginus »

adwn wrote: post #143
archi42 wrote: post #68

Earlier quoted context omitted.

Residential batteries are not that expensive anymore, at least not all of them. That's a misconception I also held until a few years ago ;-) My first 14.3 kWh pack cost about 2800$ DDP from China, delivered 03/2023. For that one I did calculate how long it took for amortization, which I projected at about 5 years. The second, identical pack was delivered 08/2024 and cost 2000$ DDP. Since we got an EV that's drawing a…

Today you can already get 51.2 V, 16 kWh batteries complete with balancer and BMS from a European supplier for 1200 € (1400 US$): https://www.nkon.nl/novat/nkon-ess-eco-s-51-2v-16-1kwh-thuis...

That looks quite a bit cheaper than the pricing I'm used to seeing, like less than half - not saying they're bad, but probably there's a DIY and risk factor involved compared to buying a more established brand like BYD or Huawei.

I'm just pointing out this is way lower than typical pricing

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