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A comment on Can "second life" EV batteries work as grid-scale energy storage?. Parent comment

Re:Can "second life" EV batteries work as grid-scale energy ... by archi42 on Thursday October 23, 2025 @05:34PM (#45687518)
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 about 14kWh per day, I didn't bother doing the math and just ordered it.

These are 280Ah 16S 51.6V packs, based on the EVE LF280K. In an enclosure, with a BMS (Seplos, 200A) and a dedicated balancer. They are good for 6000 cycles at 140A or less [each]. Mind these were both part of small bulk orders - I think each time we ordered 6 to 8 of these, which reduced shipping costs.

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Re:Can "second life" EV batteries work as grid-scale energy ... by torginus on Thursday October 23, 2025 @06:19PM (#45688090)
My new batteries were about 250EUR/kWh - my 10KWh unit cost 2500 EUR - scaling it up to a decent used 5 year old EV price - you can have one for 15k with 60+ kWh batteries, so I'd say it's at a very similar price.
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Re:Can "second life" EV batteries work as grid-scale energy ... by satellite2 on Friday October 24, 2025 @06:25PM (#45699734)
Do you mind citing providers/product names?
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Re:Can "second life" EV batteries work as grid-scale energy ... by dzhiurgis on Sunday October 26, 2025 @06:15AM (#45710567)
You wanna check how much V2G inverters cost first.

If you don't work from home it makes 0 sense either.

IMO we are long way from proving V2G usefulness. Micromanaging your car SOC every night to save $2 is nuts.

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Re:Can "second life" EV batteries work as grid-scale energy ... by adwn on Thursday October 23, 2025 @11:56PM (#45690606)
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...
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Re:Can "second life" EV batteries work as grid-scale energy ... by torginus on Friday October 24, 2025 @04:12AM (#45692173)
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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Re:Can "second life" EV batteries work as grid-scale energy ... by adwn on Friday October 24, 2025 @05:09AM (#45692527)
Maybe, but I think the premium charged by the main manufacturer's is unjustifiably high. Those battery boxes are relatively dumb: besides the cells, they just need some voltage and temperature sensors for monitoring, some power electronics for balancing, a microprocessor, and an enclosure with connectors. Unlike a grid-tied inverter, this is a really simple system, and there's no way a 500–700% price premium over the cells is reasonable.
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Re:Can "second life" EV batteries work as grid-scale energy ... by SirFredman on Friday October 24, 2025 @05:22AM (#45692616)
And the nice thing is, prices will only get lower. They also have a 32.15kWh system for €3500,- which is insane.
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Re:Can "second life" EV batteries work as grid-scale energy ... by adwn on Friday October 24, 2025 @06:12AM (#45692950)
Unfortunately, almost all three-phase [1] on-grid inverters that are on the market, especially hybrid inverters, only support batteries with much higher voltages, like 150 V or even more.

[1] Three-phase wiring in homes seems to be very rare in the US, but is extremely common in Europe.

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Re:Can "second life" EV batteries work as grid-scale energy ... by archi42 on Saturday October 25, 2025 @06:52AM (#45702802)
The trick is to get an inverter with a 48V battery interface, that's not locked down to a specific manufacturer.

But you're right, most installers do high voltage batteries.

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Re:Can "second life" EV batteries work as grid-scale energy ... by Hilift on Friday October 24, 2025 @12:27PM (#45696215)
I would take that further and say that residential solar without batteries has been proven to be a bad solution. Solar with batteries allows utilities and consumers to schedule when power can be sent to the grid. California utilities consider solar without batteries a PITA, and incentive structures have changed to reflect that shift in policy.

https://www.canarymedia.com/articles/distributed-energy-reso...

https://enphase.com/blog/homeowners/understanding-nem-30-and...

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