EV battery packs and home battery packs are not so different. Both typically use a big pile of lithium-ion cells to store energy. In cars, they’re used to get us around, while at home, they’re used to run our appliances and store energy sourced from solar panels. One point of difference is that home packs seldom need to deliver high currents in the same way as automotive packs. Thus, a tired EV battery pack could theoretically serve as a home battery if you so desired. Forget theory, though, because Dala’s already out there doing it.
Dala runs a channel on YouTube called Dala’s EV Repair. He’s explored a number of neat EV topics over the years, from oddball CHAdeMO converters to battery upgrades for older models. But he’s also explored how EVs and their parts can be used in broader ways, with his home battery project being a perfect example of this.
The focus of his project, which took place in 2023, was to see how easily an old EV pack could be hooked up to the grid. This isn’t some big complex build where the individual cells are stripped out and repurposed. Instead, Dala basically just yanked the pack as a whole and hooked it up.
The build starts with a look at Dala’s workshop solar setup. He has a solar installation on the roof capable of delivering 7 kW at peak output. This is paired with a Fronius Gen 24 inverter, which allows the solar panels to be used to power the mains circuits in Dala’s workshop. He then added a battery from a 2017 Nissan Leaf to the system. This allows the battery to store energy generated by the solar panels during the day. In turn, in situations where the solar panels aren’t producing enough energy, such as at night, the battery can make up the difference to keep the workshop powered.
The key to the system is a piece of software of Dala’s own creation. Known as Battery-Emulator, he has made it available on Github. It’s a tool that communicates with the Nissan Leaf battery pack over its standard CAN bus interface. It then translates information from the battery, like state-of-charge and status, into RS485 signals that the Fronius inverter can understand. The software itself runs on a small ESP32 microcontroller board produced by LilyGo. If you’re unfamiliar, a microcontroller is basically a programmable piece of electronics that in this case, is acting as a translator between the Leaf battery and the solar inverter.
Notably, Battery-Emulator isn’t just limited to working with the Leaf battery. It will also work with batteries from the Nissan e-NV200, the Tesla Model S, 3, X, and Y, and the Hyundai Kona, among others. Similarly, it will work with a range of inverters, including products from Fronius, Sungrow, GoodWe, and Solis.
In his video, Dala shows us his proof-of-concept setup, which he had run for 2 months. He simply has the big Leaf pack sitting on the ground, hooked up with a bunch of cables. The high-voltage connections are hooked up to the inverter via a junction box. Meanwhile, the communications wiring from the battery is hooked up to the LilyGo ESP32 board’s CAN bus port. Its RS485 port then sends the relevant data to the Fronius inverter. The ESP32 board runs off 5V sourced from a USB wall charger. The battery also gets a 12-volt feed from a mains adapter to energize its contactor and internal electronics. This is necessary in the absence of the 12-volt lead-acid battery and DC-DC converter that would normally provide this power.Â
His future plans involve building a proper housing and foundation for the battery, including some fireproofing to protect his workshop if anything should go wrong. Ultimately, though, the simple setup seen in the video shows just how easy it is to use the battery as a home storage solution.
It’s hard to say whether builds like this will become common, as working with EV batteries safely takes a special set of skills. In any case, though, Dala’s work has made it far easier for those experienced in electronics to use old EV batteries with their home solar systems. It’s practically plug-and-play if you know what you’re doing!
Image credits: Nissan, Dala’s EV Repair via YouTube screenshot
Yanking out the battery pack seems like too much work.
Can’t you just park an old Leaf next to your house?
We off-grid folks have known this for several years. Back in the day you could pick up a used Leaf battery from a wrecking yard or shop for $300-500. And for most off-grid homes it was more than sufficient for years of use. Once this became common knowledge, the used Leaf batteries went up to $2000+. Also, when used off-grid, their 12v architecture made them plug and play without reprogramming. I assume this guy was using a grid tie-in which why he needed the special programmer. I can’t afford a PowerWall, so I wish I could get one of these, but I found out after everyone else did.
Waiting for the article where DT plugs his pos Leaf into his place.
And totally fries the remainder of his shit battery trying to use the microwave to heat up his shower spaghetti.
I always wonder if insurance would cover those components, or a house fire claim if this was installed.
You jumped right into explaining how it works without an overview of what it is. I could have used some setup on this explaining:
system components (Leaf battery, custom controller, Fronius Inverter, ABB charger, roof solar system, 12v converter, ??)
system capabilities (charge battery from solar or mains?, run house on solar?, upload solar to power company?, draw house power from car battery when solar not available, house battery backup for x hours?)
costs and savings, is solar required to make it work, and will a bad Leaf battery still make a decent home backup battery
Dala should have left the Leaf in one piece and hanged it whole to the wall, for extra pizzazz
While I love the idea, the probability of someone making a mistake and starting a fire that burns down not just their own house, but their neighbors as well, frightens me.
Presumably municipal planning departments would have something to say about a person building this without a permit and inspections?
Exactly, rules, regs, and insurance seem like obvious hurdles. I cant imagine an insurance company knowingly insuring a home with a used EV battery as its power source. I like the idea, but too much bureaucracy/regs stand in the way.
I should add that I dont think the risk of fire is much greater than a new battery storage system if you buy the right pack, but insurance wont see it that way.
Is the common solution for home power storage a bank of deep-cycle batteries? If so, how does this battery compare price and safety-wise to the standard option?
Lithium started replacing lead pretty much as soon as it became available. Why deal with gallons of sulfuric acid and a Superfund site worth of lead that need regular testing and maintenance when you can have a maintenance free Powerwall-style device? It’s the same amount of energy with less spicy stuff to store it in.
The LiFePO4 batteries are perfect for this with their lower energy density and inherent resistance to thermal runaway.
It’s now 2024. V2H has been a feature of the Leaf for over 10 years. Where are the affordable, commercially available bi-directional home chargers?
Good question! I noticed that the Dala’s code supports CHAdeMO so you can DIY a V2H setup with it, but I think you need an inverter that supports battery operation, which most home solar inverters don’t.
In the EU the hybrid inverters are bit more expensive than normal ones, but not much – currently it would make sense to buy a hybrid even if the plan is to install a battery pack some time in the future. The problem is that the battery packs are totally overpriced considering the capacity etc. With this diy-solution you could install an used vehicle battery which costs much less than commercial batteries. Or use the vehicle through chademo.
The big(?) thing here is that the diy method works. So… where are the commercial products? V2H/V2G have been discussed ages, as mentioned above.
It’s definitely a more expensive inverter to use a battery vs only grid tied.
you need an inverter that supports battery operation, which most home solar inverters don’t
And so the mystery deepens…
Not sure if they’re considered affordable but check out Fermata Energy, dcbel r16, and Wallbox Quasar.
$5k for a basic 15kWh dcbel r16 bidirectional battery backup isn’t so bad. That math might change quite a bit with blackout mode though.
$4k for a Wallbox Quasar 2 with no battery is steep.
Is it just me or does the box on the wall in the last picture say ASS on it? (sorry I am 5 years old)
ABB actually, which stands for Ass-Butt-Butt or ASEA Brown Boveri depending on preference.
I used to work for ABB, can confirm it definitely stands for Ass-Butt-Butt.
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“The focus of his project, which took place in 2023”
Jeez, Lewin, way to remind us that the years quickly roll by as the universe continues its inevitable march towards infinite expansion and eventual heat death.
I am not ready to have lithium batteries near my house. I have seen a fire in a workshop started by a drill battery on its charger. Fortunately, it was in a welding shop so once the batteries and tools on the shelf were burned, the fire died out.
My man, you already have lithium batteries IN your house if you have a laptop, smartphone, sealed (no replaceable battery) smoke detector, or gadgets rechargeable by a USB charger. Likely the earbuds you shove in your ears are lithium-powered, too.
Those are much less likely to lead to an unstoppable inferno if they ignite
All of those are orders of magnitude smaller than a car battery pack. The surface area to volume ratio is also a lot different. This means that in the event of an exothermic reaction, there is more interior volume producing heat and less surface area to dissipate that heat.
Not all Lithium batteries are the same: Lithium ion batteries can ignite under the wrong circumstances, but lithium iron phosphate (LiFePO4) batteries are much more stable, (but slightly less energy dense).
For powering a house, lithium iron phosphate is a much better and safer choice.
With lithium ion cells (for anything from cars to phones), I’d stick to good quality packs, only used in the way they’re designed for. Cheap after-market packs, or using them with the wrong charger etc is when problems happen.
I watched a Milwaukee battery on a Milwaukee charger go up in flames last week. We never go aftermarket because of the lower quality and Milwaukee is about as good as they come for power tools.
Man this is great. Love to see the hacker spirit applied to used batteries!
Jason’s chainsaw?
This is the kind of stuff I’m excited about as EV’s get more popular. The secondary market and repurposing of components will allow for so many useful projects
Man, I miss Radio Shack.
Seconded. I think of something I need from them about once a month.
Yes and no. Last time I walked into a Radio Shack was about 2014 in search of a CR2032 battery. They wanted $6 for a single battery!!!!!!!!!!! I walked out dumbfounded they would alienate anyone actually willing to come into the store at that time in their history. They were just begging to go under.
I just picked up a three pack of panasonic CR2032 button cells from Daiso (Japanese 100 yen store/dollar store) for $1.75.
It still exists in Charlevoix! https://www.cvxradioshack.com/
Alaska, too. I swing by the one in Valdez every time I’m down there.
“Why does Radio Shack ask for your phone # when you buy batteries?”
-Kramer
Haha, at first I thought this was a riddle.
Remember the monthly battery cards?
No, didn’t do those there but do have fond memories of Radio Shack
The UK equivalent was Maplins, and while it was never the cheapest place, sometimes you’re willing to pay over the odds for a cable/battery/plug/component right now. Rather than waiting for Amazon to deliver a cheaper one tomorrow.
They’re defunct now, of course.