lincomatic
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Idea: Leaf Battery for 400V Powerwall?

Wed Feb 05, 2020 10:52 am

My 2011 Leaf is on its last legs. SOH is only 47%. After going through a lot of analysis, and finding out that it's not easy to do an upgrade to a higher range battery, I realized that the battery is worth more to me than the entire car. It still has >11kWh capacity left in it, which would make it a nice candidate to repurpose as a back up battery for my house.

Lots of people are taking Leaf batteries apart, making 48V modules, and building powerwalls out of them. I was thinking, wouldn't it be a lot safer, less labor intensive, and better for battery management if one were to just leave the Leaf battery pack intact, and reuse the existing charger and BMS? Solar inverters made for PV strings can easily handle the ~400V output of the Leaf battery.

So the basic idea is to extract whatever components I need from the Leaf to charge the unmodified battery pack using my OpenEVSE J1772 EVSE. Then I would use the battery to power a solar string inverter. Does anyone have any information on which components to extract from the Leaf and what I would need to do to allow charging? (I imagine that various faults might be generated within the system of certain components are missing).

The BMS is in the battery pack. I need the charger, and also the VCM? Does it need to handshake w/ any other control modules just to charge?

coleafrado
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Re: Idea: Leaf Battery for 400V Powerwall?

Wed Feb 05, 2020 11:20 am

The battery shouldn't really be worth more than the entire car unless the body is completely trashed. An 11 kWh pack should be worth about $1100, the rest of the car between $2-3k. If you just want to buy some batteries for a home, 200 Ah LiFePO4 cells can be bought from Alibaba for barely $100/kWh. There's also a flourishing market on eBay for Leaf cells - maybe you could buy a 40 kWh pack from a wreck, part out your pack for $1500-2000 on eBay, and end up with a working 150-mile car for ~$2-4k.

Battery upgrades aren't that complicated - it's just a matter of finding a wrecked 40 kWh pack, locating a shop that has a lift and knows how to rework a couple parts of the wiring harness, and convincing mux or Dala to send you their adapter kits. Someone reportedly even got Nissan to program their car to accept a 2018 pack.

The issue with using the battery directly as a powerwall has been discussed all over; the issue is that it's not worth it. It doesn't make sense to use a solar inverter and a J1772 charger, and have to deal with the pack constantly balancing, when the cells could be taken out and reconfigured to a 24V or 48V system. J1772 is a standard for vehicles with onboard chargers to draw AC power - and the Leaf OBC is extremely difficult to get working when it's not hooked up in the car.

The whole benefit of a Powerwall (from Tesla or others) is that it automatically protects your house from outages and charges itself whenever electricity is cheapest. The Leaf battery by itself does nothing of the sort, so retrofitting that functionality is likely to exceed the price of a pre-manufactured Powerwall.

The only thing you need to open the contactors to the pack is a 12V signal on a couple wires on the signal connector of the pack, but unless you have all the inverter/charger hardware ready on the other side, you're not saving yourself anything vs a commercial battery.

https://mynissanleaf.com/viewtopic.php?t=20006
viewtopic.php?f=9&t=17879

cwerdna
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Re: Idea: Leaf Battery for 400V Powerwall?

Wed Feb 05, 2020 6:56 pm

coleafrado wrote:
Wed Feb 05, 2020 11:20 am
The whole benefit of a Powerwall (from Tesla or others) is that it automatically protects your house from outages and charges itself whenever electricity is cheapest.
I wasn't aware until I stumbled across https://teslamotorsclub.com/tmc/threads ... on.130085/ that the transfer time on Powerwall in the event of an outage is quite long and MUCH longer than that of any decent UPS, so computers (for example) might still reboot or lose power.

I also was unaware of the 65 hz power issue that UPSes might believe is bad power.

Not sure if the situation has changed since I have no plans for any such system due to my (temporary) living situation and my non-ownership of the house I live in.

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coleafrado
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Re: Idea: Leaf Battery for 400V Powerwall?

Thu Feb 06, 2020 2:17 am

cwerdna wrote:
Wed Feb 05, 2020 6:56 pm
I wasn't aware until I stumbled across https://teslamotorsclub.com/tmc/threads ... on.130085/ that the transfer time on Powerwall in the event of an outage is quite long and MUCH longer than that of any decent UPS, so computers (for example) might still reboot or lose power.

I also was unaware of the 65 hz power issue that UPSes might believe is bad power.

Not sure if the situation has changed since I have no plans for any such system due to my (temporary) living situation and my non-ownership of the house I live in.
As far as I know, 50-1000ms delay is standard for the industry. The relays aren't capable of toggling back and forth to test for short circuits before lighting up any faster. If you need backup power right at a specific device, make sure your backup UPS will accept 65 Hz.

It doesn't really make sense for a renter, obviously, unless you can convince your landlord it's worth their investment.

cwerdna
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Re: Idea: Leaf Battery for 400V Powerwall?

Thu Feb 06, 2020 2:40 am

coleafrado wrote:
Thu Feb 06, 2020 2:17 am
It doesn't really make sense for a renter, obviously, unless you can convince your landlord it's worth their investment.
At this point, that would be impossible.

I live in a house my parents own rent-free but they don't live here. In theory, they're supposed to move back at some point. A few years ago, they told me they would move back "next year". That hasn't happened. Whenever that happens, I'm moving out.

The only time they might be willing to spend big $ for something like Powerwall is if http://www.pge.com/psps become frequent, long and unbearable. I've so far endured two such outages. I'm not thinking straight about the length of outages right now. The 2nd one began on a Saturday night and IIRC, power didn't return until sometime Monday. I was already on a plane to Japan on a Sunday morning.

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jlv
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Re: Idea: Leaf Battery for 400V Powerwall?

Thu Feb 06, 2020 8:08 am

cwerdna wrote:
Wed Feb 05, 2020 6:56 pm
I wasn't aware until I stumbled across https://teslamotorsclub.com/tmc/threads ... on.130085/ that the transfer time on Powerwall in the event of an outage is quite long and MUCH longer than that of any decent UPS, so computers (for example) might still reboot or lose power.

I also was unaware of the 65 hz power issue that UPSes might believe is bad power.

Not sure if the situation has changed since I have no plans for any such system due to my (temporary) living situation and my non-ownership of the house I live in.
The end of the TMC thread says Tesla can now set the "turn off the inverter" frequency, and many people have reported success lowering it to 63hz, such that the inverters turn off yet the UPSes are happy.
LEAF '13 SL+Prem (mfg 12/13, leased 4/14, bought 5/17, sold 11/18) 34K mi, AHr 58, SOH 87%
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lincomatic
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Re: Idea: Leaf Battery for 400V Powerwall?

Thu Feb 06, 2020 4:07 pm

Thanks for the reply.
coleafrado wrote:
Wed Feb 05, 2020 11:20 am
The battery shouldn't really be worth more than the entire car unless the body is completely trashed. An 11 kWh pack should be worth about $1100, the rest of the car between $2-3k. If you just want to buy some batteries for a home, 200 Ah LiFePO4 cells can be bought from Alibaba for barely $100/kWh. There's also a flourishing market on eBay for Leaf cells - maybe you could buy a 40 kWh pack from a wreck, part out your pack for $1500-2000 on eBay, and end up with a working 150-mile car for ~$2-4k.
Actually, in my area, I don't see the resale values that you state. For instance, there's a Leaf that's a year newer, has lower mileage, and has the same ~36mi range that's been on the market for a month for $3400 with no takers. I haven't been able to find cheap battery packs in good condition.. if you have good sources, please let me know.

Battery upgrades aren't that complicated - it's just a matter of finding a wrecked 40 kWh pack, locating a shop that has a lift and knows how to rework a couple parts of the wiring harness, and convincing mux or Dala to send you their adapter kits. Someone reportedly even got Nissan to program their car to accept a 2018 pack.
I have an MSEE, have been working on cars my whole life, and besides being co-designer of OpenEVSE, I also designed the LeafCAN SOC meter viewtopic.php?f=44&t=8673&p=193095&hili ... an#p193095 , so I'm up to the challenge of doing the work myself. But I spent hours reading muxsan's thread, and went to his website, and can't see that he's actually selling his CAN MIM board, or specifics on how to configure it. While it would be fun to spend time learning how to hack it myself, I'm simply don't have that much time to devote to this project, especially when (1) the battery is still going to overheat and wear out before its time, just like my original one, since it doesn't have cooling, and (2) it's still going to have subpar range. It's worth it to me only if it can be done for ~$2500, and doesn't require zillions of hours to do. So you're saying that muxsan solved all the problems, and we can now transplant any arbitrary model year's battery pack into a 2011? If so, I guess I need to try to get more info from muxsan backchannel, and possibly convince him to sell me one.

The issue with using the battery directly as a powerwall has been discussed all over; the issue is that it's not worth it. It doesn't make sense to use a solar inverter and a J1772 charger, and have to deal with the pack constantly balancing, when the cells could be taken out and reconfigured to a 24V or 48V system. J1772 is a standard for vehicles with onboard chargers to draw AC power - and the Leaf OBC is extremely difficult to get working when it's not hooked up in the car.
The whole benefit of a Powerwall (from Tesla or others) is that it automatically protects your house from outages and charges itself whenever electricity is cheapest. The Leaf battery by itself does nothing of the sort, so retrofitting that functionality is likely to exceed the price of a pre-manufactured Powerwall.
Actually, I don't necessarily need automatic failover, although that would be nice. I might just use it to power only a small isolated part of my house that could be on a dedicated circuit, and when the grid goes down. And cost wise, there's a huge difference. The Powerwall costs about $7800 installed, and is 14kWh. My Leaf pack has more than 11kWh of capacity left in it. If I took it apart and reconfigured it for 48V, I could pair it to an Outback GS4048 for <$2K. Throw in another $1K or so for other stuff like contactors, BMS, etc, depending on how much stuff I build myself and/or buy recycled. Then, I was hoping I could sell off the rest of the car for ~1-1.5K.

I came up w/ the using the Leaf pack intact idea because I liked the idea of using its existing BMS, labor saving of not having to take it apart, safety, because it's already packaged up in a well designed metal box, and because it looks like no one's gone that route yet.

I appreciate your input & info

Oilpan4
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Re: Idea: Leaf Battery for 400V Powerwall?

Fri Feb 07, 2020 8:32 am

Forget that. Plus where you going to get a 400v DC to 120/240v AC power inverter?
I would break the pack down into 24 or 48v sections. You got chargers, inverters for those voltages. Sell everything else you don't need.

Battery upgrades are possible now. It only really gets difficult when you want the much bigger and heavier 62kwh batt.
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lincomatic
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Re: Idea: Leaf Battery for 400V Powerwall?

Fri Feb 07, 2020 11:08 am

Oilpan4 wrote:
Fri Feb 07, 2020 8:32 am
Forget that. Plus where you going to get a 400v DC to 120/240v AC power inverter?
I have sources for the inverter
I would break the pack down into 24 or 48v sections. You got chargers, inverters for those voltages. Sell everything else you don't need.
Yes, I know, this is how most people do it. It's easy to just bolt a bunch of them together and stack them on a shelf, and have a huge fire hazard. But then you have to homebrew the BMS, get an expensive fireproof cabinet, and spend hours designing it. Reusing the everything from the Leaf intact, if possible, simplifies things a lot, and you don't need giant wires, because the current is so much lower at 400V than 48V.
Battery upgrades are possible now. It only really gets difficult when you want the much bigger and heavier 62kwh batt.
That's what everyone says, but where do you get batteries cheap, and how do you do it? I don't think it's worth investing $4-5K into a car that still has shorter range than is really practical (mine doesn't even have a QC port), and how many years can I use it before the 100F+ summer temps destroy the replacement battery, just like it my original? It's only worth it to me if I can swap batteries for ~$2.5-3K. And it's not worth my time to go buy another pack and swap out the modules, unless it cant get me at least 100mi range.

If know where I can get a Leaf battery that's in good shape and affordable, please let me know.

coleafrado
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Re: Idea: Leaf Battery for 400V Powerwall?

Fri Feb 07, 2020 1:09 pm

How much would it cost you to operate a gasoline vehicle for five or six years with a 100-mile daily travel distance? That number is likely to exceed by several $k what you'd pay to repair your Leaf and charge it over that same time period. A 3-year lease of a new Leaf is likely to cost in the range of $12-15k. Owning a car, any car, isn't cheap. There's no magical rule that says your car always costs less to fix than it's worth right now.

Where to actually find a cheap-ish Leaf battery that'll last 7-8 years? Here's a search that can be narrowed down to your state: https://erepairables.com/salvage-cars-a ... issan/leaf. Wrecks are the only place you'll find the packs 'cheaply,' as anywhere else is either Nissan (charging $6-13k for a 30-40kWh pack) or some eBayer looking to make a 25% profit extracting the pack from a wreck and parceling the rest of the car out. Right now, I can see a wrecked 2019 (at least 40 kWh) selling for $3k in Maine plus delivery.

If you want cheap and maintainable transport, an e-bike is the way to go. The only trouble is that it's not as safe if there are cars around.

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