Cheap EV and v2h

[Kenny000666]

Hi guys

Just looking around and seen some super cheap 10 yr old Nissan leafs for sale.

24 kWh for £5k?

That would be around 7 US3000c batteries which would be around double that price.

If we hook it up as a v2h, the car makes quite a good deal to act as an additional battery store? Might just cancel my orders of additional pylontechs and put the money towards buying one of these cheap old EVs. Am I missing something?

[Mr Gus]

So are you intending to strip it down, install the batts in racks & wrangle the software like the Oslo based guy years back? ..or is the idea to hace it fed from the driveway / garage into the house?

I ask because Vehicle to grid where early leaf was concerned was not all plain sailing as I recall.
Maybe ou can expand on your initial plan?

[Kenny000666]

Ah

I was thinking it would be as simple as hooking the car up to a charger? And voila it can charge overnight, and give me power back when I need it

lol, it’s a spur of the moment idea as I came across a cheap Nissan Leaf on gumtree

[Mart]

Hi. The V2G/H kit is very expensive, several £k's, but is still a very practical solution.

I tried to take part in a V2G trial back in late 2019 early 2020, but the DNO said no as the kit wasn't certified (G100 I believe) to guarantee it wouldn't discharge in addition to PV. So my connection couldn't cope with any extra, and I got a hard NO.

But I assume V2G/H kit certified as compliant by UK DNO's now exists.

PS - To make it worse, the trial was expected to last 2yrs, with the option to buy the kit for V2H use, at the end for ........ £1.

[marshman]

Also doubtful that a 10 year old Leaf battery still has 24kWh capacity. The Leaf did not have the best BMS.

[ducabi]

I don't know what battery type it exactly is but the warranty seems to be for 100k miles. 24kwh is roughly 80miles, so the warranty is for around 1000-1500 cycles. Most of storage batteries are meant to cope with 6-10k cycles, car batteries are usually for 10x less.

[Swwils]

The battery is almost guaranteed to be good.

Any bad batteries were replaced. So the car may well have a brand new (2 year old) battery in it.

V2G possible with all leafs under 10 years old, it's alot easier with certain models though.

The BMS will report each modules SOH with the right tools.

String together 7 modules into a pack, 14S 120-200a BMS and away you go.

[marshman]

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[Kenny000666]

As I understand the battery industry, generally cars want tier 1 batteries (batteries with that are new generally healthy?). Once they are not longer useful in cars the industry recycles them for storage? I.e powering homes, buildings etc.

So technically a car battery that’s no longer useful for driving should still be useful for residential storage? I mean, I don’t know if this was the idea 10 years ago. But I read articles that old Nissan EVs are recycled to power buildings in Japan.

[Oldgreybeard]

There's an inherent issue with cycle life, mentioned earlier. EV batteries aren't designed to have a high cycle life, as they just don't need it. EV battery packs are designed to be compact, light, deliver high peak power and to charge quickly, as these are far more important in a car than cycle life. For an EV, cycle life is almost irrelevant. Take our little EV as an example. It has a useful range of around 200 miles and we drive a bit less than the national UK average, around 5,000 miles a year now. Ten years would be 50,000 miles, so around 250 full battery cycles.

Our house battery has been installed for nearly two years now, and is showing around 500 cycles. In ten years it will have done around 2,500 cycles, ten times more than the car. That's one reason why I opted to use LiFePO4 battery packs for the house, they are optimised for a much higher cycle life than most EV battery packs (the exception being the "made in China" Tesla Model 3s, I believe).

The cycle life issue can be mitigated to some extent by only partially cycling the battery each day. This makes a significant difference to life, but at the expense of needing a much larger battery for a given daily demand. Using, say, 30% or so of a battery's capacity for each charge/discharge cycle extends the life a great deal, but there's no way that will make up for the big difference between the two different types of cell chemistry.