Using almost new 40kwh Nissan Leaf possible battery bank for house

https://www.ebay.co.uk/itm/255408224336?hash=item3b77843850:g:6b0AAOSwu3xiG1oT

Anyone here using old car batteries as backup.

The link is for a 2021 damaged Leaf 40 kw with under 10k on it.

the_amazing_raisin

You'll definitely want to make sure the car still has the battery. Still runs so that implies it does, but no harm double checking

There's plenty of videos online about getting the battery modules out of a Leaf

You'll need to string them together to make 48V or whatever the battery voltage is. You'll probably have several groups in parallel then wire them all in series

Or the other way around it that's easier

You'll need your own BMS as well, preferably one that can do cell balancing to account for any difference in the battery modules

slave1

Not DIY route, some serious voltage there and batteries you'd want to store away from the house. I'd rather drop €5-6k and get 40kWh Lithium batteries from China

DrPhilG

Friend of mine has done it. Personally I did what @slave1 suggested and bought Chinese Lifepo4.

the_amazing_raisin

It's a shame the front is smashed in, if the Chademo port was intact you'd be able to get a v2g charger for a few thousand and just plug the car into your house without having to rip the battery out

https://www.boards.ie/discussion/comment/118826841#Comment_118826841

Yea thats what I was thinking, no battery stripping

...Ghost...

Plenty 24kWh Leafs available for sale with the CHAdeMO fully intact. I'll be selling mine soon enough with about 75% battery capacity. I would keep it for solar PV but that project is a long way away.

unkel

The ship of cheap lithium car batteries has long sailed. It is cheaper per kWh to go the China LiFePo4 route yourself. And most importantly, no car battery is safe from a fire / explosion point of view, none should be stored in your house. On the other hand, LiFePo4 is safe.

JimmyVik

https://www.boards.ie/discussion/comment/118826841#Comment_118826841

How much would one of those setups cost if you already had PV on the house?

I know someone who is getting rid of a 24kw leaf but would keep it as a battery for their house of they could instead.

unkel

CHAdeMO V2G charger costs $3k plus shipping plus VAT plus import duty last time I looked. Forget it. If you want home storage, get a battery inverter and do up your own battery. From about €2k all in for 10kWh

Tell your friend to sell his Leaf for scrap (if it doesn't work anymore / won't pass an NCT), these fetch big money now. Will easily pay for the total cost of the above setup.

JimmyVik

https://www.boards.ie/discussion/comment/118855325#Comment_118855325

If you had a 10kw battery already could you add one of those diy ones to it easily?

unkel

Short answer is no. You can't just mix and match battery cells or packs. They have to be of equal capacity, equal chemistry, equal internal resistance, etc.

Battery capacity is in kWh BTW, the power of a motor or the speed at which a battery can charge or discharge are in kW

the_amazing_raisin

https://www.boards.ie/discussion/comment/118855325#Comment_118855325

Well that's €3k for a mobile 24kWh battery or €2k for a static 10kWh one

I'm not sure I'd be thrilled having a Leaf stuck on the driveway, but as €/kWh goes it's actually not bad

Personally I'd probably still sell the Leaf and use the money to buy home batteries, but if I already had enough storage then I'd consider adding a V2G wallbox for the expanded storage

graememk

https://www.boards.ie/discussion/comment/118856112#Comment_118856112

But if the leaf was sold, for say 5k?

Last 20kwh of cells cost me 2270, say 800 for inverter and another 500 say for install, bms and miscellaneous things is 3600. Takes up a fraction of the space.

slave1

I cede to my electrician when this came up for conversation when I was looking to do a DIY battery install, he veered me away from car batteries with two words "thermal runaway" which he has witnessed and it's basically a violent fire you cannot put out.

the_amazing_raisin

https://www.boards.ie/discussion/comment/118856339#Comment_118856339

Doesn't the Leaf use LFP cells though which can't catch fire?

EDIT: Nevermind, I found out it uses NMC cells

the_amazing_raisin

https://www.boards.ie/discussion/comment/118856171#Comment_118856171

True, I guess I'm trying to say that DC V2G wallboxes aren't actually the worst idea economically even if they're a lot more expensive than AC ones

It's also worth looking at power delivery, most of the V2G boxes seem to be able to deliver a fair bit of power from the car. The VW one claims up to 22kW, although I suspect that's 3 phase so probably more like 7kW here

As I said before, I still think you need some sort of static battery for the house. But if you had €3k going spare and an EV sitting in the driveway then it seems like a good investment to get a V2G box to use the EV as expanded battery storage