Nissan LEAF as Home Energy Storage

[EEVblog]

So you'll soon be able to use your LEAF as home battery storage, that's pretty cool.
But this article says it could cost $10,000 for the widget
https://thedriven.io/2020/07/09/nissan-leaf-owners-should-be-able-to-use-their-cars-to-power-their-homes-later-this-year/

[Ice-Tea]

No, it's not cool. Dedicated home batteries use a different chemistry and promise 5000+ cycles. Did some back of the envelope some time ago, works out to about 0.1$/kWh charged/discharged.

Car batteries, with 1000+ cycles work out to, what, 0.35$/kWh charge/discharged? Thanks, but no thanks.

[SilverSolder]

We recently had a five day power outage here.   I used a hybrid car as an emergency generator, with an inverter on the 12V circuit.  Not much power - about 1kW - but enough to keep the fridge running and a couple of lamps.

The hybrid car just sits there, cycling on and off, topping up its high voltage battery which then feeds the whole show.   Not as efficient as a separate generator...   but the overall cost is low, no storage needed for a generator that would only get used once every few years!

So back on topic:  An electric car that was able to act as a back-up for the entire house....   is actually not a bad idea at all! 

[wraper]

Instead of this gimmick they should rather add battery thermal management system so their batteries do not degrade at extraordinary rate. They are disgrace of electric car industry.

[wraper]

BTW why someone would pay $10k for this is beyond me. For this money you can buy Tesla Powerwall with installation included.

[RenThraysk]

https://wallbox.com/en_uk/quasar-dc-charger

"Charge and discharge your EV using advanced facial recognition and gesture control."

Sounds like feature creep has led to the $10k price tag.

[sandalcandal]

Some more news related to this project for anyone wanting to take a deeper look.
https://arena.gov.au/projects/realising-electric-vehicle-to-grid-services/
https://www.abc.net.au/news/2020-07-08/act-hooks-electric-vehicles-up-to-power-grid-in-research-trial/12436224
https://www.anu.edu.au/news/all-news/new-lab-to-help-drive-australias-low-carbon-energy-future

I'd agree with the sentiments the price for the hardware is a bit premium compared to what a well cost optimised solution could be even with "early adopter premium". I did some investigations on cost effectiveness of vehicle to grid (V2G) vs dedicated battery systems.

A 9.8kWh residential energy storage system (ESS) from LG chem is rated for a 24.3 MWh lifetime throughput down to 60% rated capacity degradation (https://solarjuice.com.au/wp-content/uploads/2018/01/lg-chem-lv-resu-limited-warranty.pdf) with a retail cost of AU$7,862.80 (https://www.ecoelectric.com.au/shop/lg-resu-10-lv-battery-system.html.html). So thats 0.326 AU$/kWh then you need to add a seperate inverter-charger which would serve the same function at the $10k wall wart vehicle to grid (V2G) interface.

As an additional datapoint for residential ESS, Tesla Powerwall 2 is warrantied for 37 MWh down to 70% rated capacity degradation (https://www.tesla.com/sites/default/files/pdfs/powerwall/Powerwall_2_AC_Warranty_AUS-NZ_1-0.pdf) at a retail cost of AU$10,000 (https://www.ecoelectric.com.au/shop/tesla-powerwall-tesla-14kwh-battery.html  https://www.tesla.com/en_AU/powerwall). So thats 0.270 AU$/kWh and you've got extra capacity at the end of warranty compared to the LG Chem and the inverter-charger is built-in too.

Now for EVs the standard warranties appear to be about 160,000 km = 100,000 miles (https://www.caradvice.com.au/859099/electric-car-battery-warranty/) finding how much energy throughput that relates to though is a bit more challenging.

Nissan leafs are warrantied to have after 100,000 miles no less than "9 bars out of 12" (https://www.nissan.com.au/owners/warranty/new-vehicle-warranty-terms.html https://owners.nissanusa.com/content/techpub/ManualsAndGuides/LEAF/2018/2018-LEAF-warranty-booklet.pdf) and confusingly the first bar segment is 15% but the remaining are 7.5% (https://cleantechnica.com/2020/01/26/2018-nissan-leaf-60000-mile-update/) so down to 60% capacity. EPA rating for the 2018 leaf (https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=42085&flag=1) shows 187.709 miles for 44.8318 kWh of charge input (probably some onboard converter loss in there) so 4.19 miles/kWh then that gives warrantied throughput of 23.9 MWh or only 532 cycles?! Looks like using your car for ESS is probably not too great in terms of warrantied life. However, I've seen anecdotal evidence the actual lifetime in general is better than warranty at 92.5% capacity for 40,000 miles (https://cleantechnica.com/2019/01/06/40000-miles-with-the-2018-nissan-leaf/) then 86.8% after 60 000 miles so on track to a bit under 80% by 100 000 miles.

The Australian 2019 leaf (2018 leaf everywhere else) is about AU$50,000 (https://www.carsguide.com.au/nissan/leaf/2019) then add on the AU$10,000 wall wart so assuming you used the warrantied throughput purely for V2G that'd be 2.51 AU$/kWh (2.09 without wall wart).

Now obviously you're paying for more than just the batteries when you buy a car. It took some digging to find but the cost of a replacement battery for a Leaf is apparently at least is JPY 820 000 aprox. AU$10,700 for a 40kWh battery (https://global.nissannews.com/ja-JP/releases/180326-04-j?source=nng&lang=ja-JP) and only available in Japan at that cost apparently so that's actually 0.867 AU$/kWh or if we dont include the expensive V2G grid tie (which you could assume as a non recurring cost?) thats 0.448 AU$/kWh not too bad. Mind you, you costs are a bit worse using this guy's quoted cost (https://forums.aeva.asn.au/viewtopic.php?t=6077) AU$ 10,000 for replacing a 24 kWh battery in a first gen leaf (which were notoriously bad btw, https://www.greencarreports.com/news/1109640_lessons-learned-from-early-electric-car-2011-nissan-leaf-at-90000-miles) and you might end up getting stiffed by dealerships like this guy (https://autoexpert.com.au/videoblog/astonishing-30k-nissan-leaf-battery-replacement-bill) with a $33,000 bill for what seems to be the same replacement as the bloke on the AEVA forum... Might be worth looking more into these wildly varying replacement costs.

If the cost of the vehicle to grid interface gets brought down to a more reasonable ~$2.5k like other existing inverter-chargers (https://www.outbackmarine.com.au/multiplus-48-5000-70-100-inverter-charger-victron) and you assume the EV batteries get degraded maybe half as much as they would driving (i.e. halve the lifetime energy throughput cost) then you could, maybe justify the lifetime costs with respect to a typical ESS system and have the benefit of not needing to spend extra capital to buy a separate 40kWh battery system.

Again, I'd expect degradation to not be as bad as calculated here particularly considering ESS use where the load characteristics will be much gentler than driving (500 cycles seems low for any cell put under typical ESS use). That being said, the warranty is the warranty and EV manufactures don't seem to have warranties covering V2G use yet so I'm just playing with numbers here.

In the end, I think in terms of straight cost effectiveness its not possible to beat the cost optimisation of a system designed specifically for ESS and at $10k you can literally just buy a Tesla Powerwall but it could maybe work and make sense in the future even with lifetime cost considerations?

Disclaimer: I'm involved in work on EVs and ESS related systems but not any V2G products... as of writing this.

Edit: To compare the loading of ESS vs driving. The Tesla powerwall is 5kW continous, 7kW peak and the wallbox Quasar is spec'd at 7.4kW. That's a 0.185 C load at max with a 40kWh battery. The Leaf's power train is rated at 110kW=2.75 C with 40kWh battery and obviously you're not going to be flooring it continuously but burst loads an order of magnitude larger.

[tom66]

The evidence so far from Leaf batteries is they have extreme calendar degradation but generally cycle life isn't a serious factor.  So it is actually in your interest to get as many cycles out of it as possible.

I don't know what chemistry Nissan are using, but it is genuinely crap, and it hasn't got any better. Other manufacturers have at least twice the battery lifespan of Nissan, and Tesla makes 500k miles / 4 years to 92% capacity still remaining. It doesn't make sense.

[coromonadalix]

Costly now,  but in the future i hope it will be more accessible,  that's a good start ...

[Ice-Tea]

As for cycle life, cars have a higher standard, so the rated lifetime is more conservative.

There's also this minor fact that the chemistry is different.

[SilverSolder]

Hard for any EV to beat an ICE for longevity.  E.g. I have an old 1990 Mazda MX5 that looks and runs beautifully,  delivering hundreds of smiles per gallon! 

It would probably have been much more expensive to keep an EV alive for this long.

[EEVblog]

As an additional datapoint for residential ESS, Tesla Powerwall 2 is warrantied for 37 MWh down to 70% rated capacity degradation (https://www.tesla.com/sites/default/files/pdfs/powerwall/Powerwall_2_AC_Warranty_AUS-NZ_1-0.pdf) at a retail cost of AU$10,000 (https://www.ecoelectric.com.au/shop/tesla-powerwall-tesla-14kwh-battery.html  https://www.tesla.com/en_AU/powerwall). So thats 0.270 AU$/kWh and you've got extra capacity at the end of warranty compared to the LG Chem and the inverter-charger is built-in too.

A Tesla powerwall in Australia is $10k + $1700 "supporting hardware" + installation according to the Tesla AU pricing page.

[EEVblog]

In the end, I think in terms of straight cost effectiveness its not possible to beat the cost optimisation of a system designed specifically for ESS and at $10k you can literally just buy a Tesla Powerwall but it could maybe work and make sense in the future even with lifetime cost considerations?

I think so too.
And it also provides greater flexibility. i.e. not having to plug in at home every day if you have charging capability elsewhere like at work.

[sandalcandal]

As an additional datapoint for residential ESS, Tesla Powerwall 2 is warrantied for 37 MWh down to 70% rated capacity degradation (https://www.tesla.com/sites/default/files/pdfs/powerwall/Powerwall_2_AC_Warranty_AUS-NZ_1-0.pdf) at a retail cost of AU$10,000 (https://www.ecoelectric.com.au/shop/tesla-powerwall-tesla-14kwh-battery.html  https://www.tesla.com/en_AU/powerwall). So thats 0.270 AU$/kWh and you've got extra capacity at the end of warranty compared to the LG Chem and the inverter-charger is built-in too.

A Tesla powerwall in Australia is $10k + $1700 "supporting hardware" + installation according to the Tesla AU pricing page.

Yeah I kinda ignored that cost. I think the supporting hardware is distribution box components and anti-islanding which you need for any ESS/generation system https://www.tesla.com/en_au/support/energy/powerwall/learn/system-design

[tom66]

Hard for any EV to beat an ICE for longevity.  E.g. I have an old 1990 Mazda MX5 that looks and runs beautifully,  delivering hundreds of smiles per gallon! 

It would probably have been much more expensive to keep an EV alive for this long.

I doubt any modern ICE with its high compression ratios, turbo, and complex exhaust systems, will survive as long as that Mazda.

There's something to be said for a simple naturally aspirated engine.

[Ice-Tea]

Hard for any EV to beat an ICE for longevity.  E.g. I have an old 1990 Mazda MX5 that looks and runs beautifully,  delivering hundreds of smiles per gallon! 

It would probably have been much more expensive to keep an EV alive for this long.

Don't think I agree. Swap the batt pack and move on. Electric motors should have any ICE beat for longevity...

[SilverSolder]

Hard for any EV to beat an ICE for longevity.  E.g. I have an old 1990 Mazda MX5 that looks and runs beautifully,  delivering hundreds of smiles per gallon! 

It would probably have been much more expensive to keep an EV alive for this long.

Don't think I agree. Swap the batt pack and move on. Electric motors should have any ICE beat for longevity...

30 years...  200K miles...   how many battery packs are we talking about?

And don't forget:  an ICE performs at 100% as long as there is any fuel at all in the tank!

Doesn't mean I don't like EVs,  I do,  but let's not ignore that they have some downsides too.

[Ice-Tea]

Pretty much any EV should be able to hit 200k miles on its first battery..

[SilverSolder]

Pretty much any EV should be able to hit 200k miles on its first battery..

The hard part for the EV is the 30 years at full performance...

[Gyro]

30 years...  200K miles...   how many battery packs are we talking about?

And don't forget:  an ICE performs at 100% as long as there is any fuel at all in the tank!

Doesn't mean I don't like EVs,  I do,  but let's not ignore that they have some downsides too.

I'm not sure about the 100% bit. ICEs loose a significant proportion of their output power over their life due to engine wear, loss of compression etc. I remember quite a few episodes of the BBC 'Top Gear' program where, in their challenges, the presenters have proudly put their second-hand performance car acquisitions on a dynamometer, only to find that they have a fraction of their original output power. I doubt they drink less fuel.

[SilverSolder]

30 years...  200K miles...   how many battery packs are we talking about?

And don't forget:  an ICE performs at 100% as long as there is any fuel at all in the tank!

Doesn't mean I don't like EVs,  I do,  but let's not ignore that they have some downsides too.

I'm not sure about the 100% bit. ICEs loose a significant proportion of their output power over their life due to engine wear, loss of compression etc. I remember quite a few episodes of the BBC 'Top Gear' program where, in their challenges, the presenters have proudly put their second-hand performance car acquisitions on a dynamometer, only to find that they have a fraction of their original output power. I doubt they drink less fuel.

Modern ICEs only go bad only if not maintained (primarily, watch those oil changes!) or if they are abused/driven hard (e.g. performance cars!) or if they have truly stratospheric mileages on them, or if you are simply unlucky and something breaks prematurely due to a flaw in materials/workmanship.  Consider also that as carbon deposits build up in an ICE, compression actually goes UP over time!  - this can become a real problem and cause knocking/pinking.

In the case of my particular MX-5, it appears to have been adult driven and its little 1.6 engine still easily beats its specification 0-60 time and does not burn any oil.  In other words, it hasn't lost performance noticeably.  I will check the compression one of the days, but modern engines are so good that I don't even think I can find my compression gauge without digging deep in the garage!

We do have several other older ICE cars in the family, and they all run like Swiss watches.  One is a hybrid Ford with >220K miles, it still beats its EPA mileage rating and gets the same mileage as new; the story is the same:  no noticeable loss of performance.   However; unlike the MX-5,  the Ford will eventually need a new hybrid battery...   at which point it will probably be scrapped due to it being uneconomic to do so.  It isn't going to make it to 30 years old, unlike the Mazda.

[wraper]

Modern ICEs only go bad only if not maintained (primarily, watch those oil changes!) or if they are abused/driven hard (e.g. performance cars!) or if they have truly stratospheric mileages on them, or if you are simply unlucky and something breaks prematurely due to a flaw in materials/workmanship.  Consider also that as carbon deposits build up in an ICE, compression actually goes UP over time!  - this can become a real problem and cause knocking/pinking.

Modern ICE is when tiny 3 cylinder engine is stressed so hard to salvage the last bit of power that it often dies at 100k km (60k miles). It's a bit different in US since they do like big cars with big engines and care comparably little about fuel efficiency.

[tom66]

30 years...  200K miles...   how many battery packs are we talking about?

And don't forget:  an ICE performs at 100% as long as there is any fuel at all in the tank!

Doesn't mean I don't like EVs,  I do,  but let's not ignore that they have some downsides too.

Plenty of EVs perform at 100% with a discharged battery too.

I mean my PHEV on pure electric gives full performance (100 hp) when the battery indicator reaches 0 miles.

In most cases the EVs that do have a 'turtle mode' only do so for two reasons:  one, to make discharging the battery to zero safer (you don't want to cut power under full acceleration, could be quite dangerous)  and two to extend the range (and make drivers be more economical) for the last few miles.

It would be sort of like an ICE car limiting the car to 2000 rpm as the fuel tank ran dry.  Most don't do that.

Early Model S had no power limit and would discharge well past 0 miles with full power available.

[SilverSolder]

Nobody is disagreeing that an EV battery is unlikely to last 30 years?

[SilverSolder]

Modern ICEs only go bad only if not maintained (primarily, watch those oil changes!) or if they are abused/driven hard (e.g. performance cars!) or if they have truly stratospheric mileages on them, or if you are simply unlucky and something breaks prematurely due to a flaw in materials/workmanship.  Consider also that as carbon deposits build up in an ICE, compression actually goes UP over time!  - this can become a real problem and cause knocking/pinking.

Modern ICE is when tiny 3 cylinder engine is stressed so hard to salvage the last bit of power that it often dies at 100k km (60k miles). It's a bit different in US since they do like big cars with big engines and care comparably little about fuel efficiency.

Even worse, when they use a tiny 4 cylinder with a turbo to pretend it is a bigger engine.   That works well...   for a while! 

The MX5 is a very light car, so even its 1.6 liter 4 banger is not stressed at all - for sure one of the reasons it still runs great.