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Old Nissan leaf battery for solar system?

  • 09-05-2020 12:08pm
    #1
    Registered Users Posts: 169 ✭✭ ReadySteadyGo


    Anyone got about experience or insight into using old leaf battery as the battery for solar system?

    How practical is it to do it today?

    Would the cost of an old leaf battery make the maths work for a battery system?

    E.g. 10kw capacity (very old very tired leaf) is very limiting for a leaf, but would be great for solar, and supports high charge discharge rates.


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Comments

  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    10kWh usable is a great battery for home attached storage. I have the same myself (but lead acid, not lithium) on grid

    Are you going on grid or off grid? How much do you reckon you can source a whole Leaf battery for, shipped to your door?

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 169 ✭✭ ReadySteadyGo


    Idk. But I guess an old gen 1 leaf should mean 5k cost is possible? And maybe more than 10kwh usable?

    Although I'm more wondering about how you would house and connect it up, and whether there are any neat solutions for that - maybe just drive an old leaf up and park it!


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    5k would be very expensive, sure you'd have a Tesla power wall 13kWh for not much more

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 169 ✭✭ ReadySteadyGo


    Yeah. I haven't actually priced it. Likely it's a good bit cheaper than 5.

    How much do you think an crashed early gen 1 leaf sells for?


  • Posts: 0 [Deleted User]


    I priced them and after derating because anything you get is on the used market for a reason...it worked out cheaper get shiny new CALB bricks direct from China.
    I have to say they're very impressive.

    Nothing I can't do with three times the lead acid though...which works out cheaper if weightier.

    Tesla po0werwalls work out pretty expensive by the time you mount it to a wall and pay to run the internal heater from the grid all Winter long.
    Why the 'ef does a battery need wifi...were they not in class that day?


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  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    Tesla po0werwalls work out pretty expensive by the time you mount it to a wall and pay to run the internal heater from the grid all Winter long.

    Something often overlooked. Tesla will not install a power wall inside any living area of your home. So if you don't have a garage, it will have to be on an outside wall. Then the heater will more than waste any production from solar PV in winter

    My own "power wall" is literally half a tonne of lead acid batteries in a steel cabinet weighing another good few hundred kg :D Charged 10kWh from solar PV today, it powered my house for the whole evening and the remaining juice is going into my EV at this moment.

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    3kW coming from the battery and 1kW coming from the grid

    512384.jpg

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Posts: 0 [Deleted User]


    Good fresh/healthy lead's closer to 98% efficient than 80% quoted everywhere.

    What it is is the 95% to 100% SOC is about 40% efficient discolouring the results. If you find a charger that charges lead to 100% I'll eat my hat.
    I've built a few and high end solar chargers will do it.


  • Posts: 0 [Deleted User]


    If you do charge lead to 100% they become immortal...shucks, if word got out that li-ion's success is fundamentally based on nobody making a decent lead acid BMS...and that we could have the same magic boxes for a quarter the cost if they were three time bigger...:rolleyes:


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    If you find a charger that charges lead to 100% I'll eat my hat.

    I'm still quite confused about what my system reports as the battery percentage at any time. It's not making much sense to me. But I ain't complaining. The figures for charge and discharge in kWh units seem accurate. And that's all that matters really. Delighted I'm getting about 10kWh charged on a good day from 16 * 93Ah 12V 3-4 year old lead acid AGM ex-multinational data centre UPS batteries :)

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



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  • Posts: 0 [Deleted User]


    Ah seeing the glitches in the matrix.
    Yeah lead acid metering is a black art. Depends on the meter and the calibration, the temperature, the discharge rate, the age, the electrolyte level, the unfactored loads....
    What's the meter? Doughnut or shunt?

    TriMetric is very good.
    SmartGauge is simple and good but tuned to read 10% lower than actual (for fleet owners).
    The only real teller is electolyte density reading which you can only do with flooded batteries.

    I calibrate the battery monitor voltage and current to a Fluke 87V.
    The capacity imperically from operational adjustments.
    100% charge to the fidelity of the hardware I use confirmed by specific gravity readings.

    Not easy.

    Some might suggest none of these problem exist with Li-ion but that's saving €200 on a high end meter and some tuning by spending thousands more on a battery.


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    What's the meter? Doughnut or shunt?

    No meter! Figures are from what the Sofar ME3000SP tells me. Or the occasional multimeter read out I take manually

    Should I care? Fairly confident the battery is charging up to about 10kWh per day, which is a bit higher than I expected. I used the settings recommended to me by the experienced previous owner, I experimented with those settings for a short bit. Battery is still contributing 3kW of the 8kW going into my car at the moment. Pretty good going. Looks like the battery is saving me roughly a euro per day on a good day. 10kWh charged. After losses, most but not all used at the higher rate. Agreed?

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Posts: 0 [Deleted User]


    Charging a battery from a battery...er...not effieient.
    Should you care? Meh...dunno...

    I meter my meters..not joking. (most lie are inaccurate tbh)
    You ought to let it charge off-load maybe 3 days once a month to give it a chance to completely regenerate. Now whether the sofar charger is good enough to do this completely...well...I'd be surprised if it is...few and far between is a genuine lead charger

    I have distrust of sofar and all these new fancy boxes...they're like pop music to me. I can tell you what I know works, not whether what you have does.

    The only way is first established what you have works, the only way to do this is with a hydrometer and an open wet cell. Then work from there..


  • Moderators Posts: 11,978 ✭✭✭✭ Black_Knight


    unkel wrote: »
    Something often overlooked. Tesla will not install a power wall inside any living area of your home. So if you don't have a garage, it will have to be on an outside wall. Then the heater will more than waste any production from solar PV in winter

    My own "power wall" is literally half a tonne of lead acid batteries in a steel cabinet weighing another good few hundred kg :D Charged 10kWh from solar PV today, it powered my house for the whole evening and the remaining juice is going into my EV at this moment.

    Ever think of doing a write up on your setup. I get the impression the battery portion of it was DIY.


  • Registered Users Posts: 54 ✭✭✭ ShareShare


    Ever think of doing a write up on your setup. I get the impression the battery portion of it was DIY.

    +1 for a write up!


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    Sofar ME3000SP is the heart of the system. It is an inverter, connected to your battery (any battery, can be lead acid or lithium) and connected to the grid. I installed it myself, but I got an electrician to hook it up inside my consumer unit (fuse box) in the house. I bought this inverter second hand from a reputable user on the main UK renewable energies forum

    The inverter has a temperature sensor, which you must connect to your battery. It also has two CT clamps, one for your solar inverter and one for the house main grid feed in your consumer unit. Based on this it decides whether to charge the battery, discharge it, or do nothing. You can also program it to charge on the cheap night rate. I will do that in winter

    I have 16 lead acid batteries (12V), in a steel cabinet, configured in a 4S4P configuration, this means there are 4 in series, to give me nominally 48V (4*12V) as the Sofar needs a 48V setup. These batteries look a bit like car batteries, but they are high end and can be deeply discharged. To about 50%. Which is high for lead acid! The batteries are all connected to each other with automotive 110A cables like these:

    s-l1600.jpg

    And the battery pack then as a whole is connected to the inverter via a 100A automotive mega fuse

    The tricky bit is to configure the settings for the inverter. I used settings recommended to me by the seller. He was very helpful and sent me a detailed email with all the settings in it

    Hope that helps :-)

    All this is installed outside of my house against the outside wall

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 169 ✭✭ ReadySteadyGo


    Very interesting. Thanks. Any chance of a photo of the batteries in your cabinet?


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    I don't think I have one at hand. But you can imagine it, it's a steel cabinet with shelves and the batteries are connected to each other with above leads.

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Moderators Posts: 11,978 ✭✭✭✭ Black_Knight


    What's the app screenshot above? That from the sofar? Looks a neat setup. Was the solar installed at the same time as all of this? Or did you have the solar with the sofar and retrofit the batteries.

    All sounds pretty straight forward when you explain it like that.
    Solar -> inverter -> fuse box
    Solar -> inverter -> big fuse -> batteries
    inverter -> CT clamps -> house mains
    Inverter -> CT clamps -> batteries
    Inverter -> temperature sensor -> batteries



    Did you knock much time off its repayment doing it yourself?


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    App is Solarman. This is an independent app (free). Inverters like the Sofar talk to its servers via wifi. One million plus users worldwide

    The Sofar ME3000 + battery system is completely independent of the Solar PV system (mine was installed at the start of last year). In fact, you can have a Sofar + battery system without having any PV. Essentially this system is the same as the Tesla Power wall. An "AC side" system

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



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  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    Did you knock much time off its repayment doing it yourself?

    €450 for the inverter second hand, including shipping
    €0 for cabinet
    €0 for batteries
    €150 for cables, disconnects (I already had a spare 25A RCBO that came with my free EVSE install back in early 2017), sundry all including shipping
    €150 for electrician

    Total cost €750 for a 10kWh usable system (cabinet easily fits another 5kWh usable should I want to increase it)

    Repayment (ROI) time: negative. If I sold the lot today, I'd get more back than what I paid for it.

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Moderators Posts: 11,978 ✭✭✭✭ Black_Knight


    unkel wrote: »
    €450 for the inverter second hand, including shipping
    €0 for cabinet
    €0 for batteries
    €150 for cables, disconnects (I already had a spare 25A RCBO that came with my free EVSE install back in early 2017), sundry all including shipping
    €150 for electrician

    Total cost €750 for a 10kWh usable system (cabinet easily fits another 5kWh usable should I want to increase it)

    Repayment (ROI) time: negative. If I sold the lot today, I'd get more back than what I paid for it.

    That's not how roi works really, though 750 is pretty cheap. Guess if you were to charge it on night rate and use that 10kWh every day that's about 300 in savings a year. 2 years should pay itself back easy given your solar. Nicely done.

    Add the cost of solar in and the ROI takes a bit of a hit I guess.


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    That's not how roi works really

    Yes of course it does. Anything you buy and you sell later for more than you paid has a pay back period of zero. And the big savings on this system is for daytime units that would have gone for free to the grid, that you now use during the day (and could not use at night). Full 18c per unit saving on those. I'm not that interested in charging up with cheap night rate, but I will look into that next winter. To keep the batteries in good condition more than anything else.

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Posts: 0 [Deleted User]


    unkel wrote: »
    I don't think I have one at hand.


    Usually means...err...yeah soon as I hide all that stuff I'd rather you don't see..:pac:


  • Registered Users Posts: 169 ✭✭ ReadySteadyGo


    SlowBlowin wrote: »
    There are ready made kits for solar conversion, just watching this now:

    https://www.youtube.com/watch?v=FlCz40bCZZM


    Just quoting this here as it is on topic for my original query but was posted in another thread.


  • Registered Users Posts: 169 ✭✭ ReadySteadyGo


    I think the guy said cell price was 170USD per kwh. Unclear if that was original capacity or current capacity.


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    I took it to mean original capacity. So almost double that price to USD300 per kWh usable, which is far too high. Tesla Model S modules are around USD1000 for close to 5kWh usable, so USD200 per kWh. And far superior to the Leaf batteries and less likely to have further degradation at the same scale. Personally I'd aim for well under USD100 per kWh.

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 169 ✭✭ ReadySteadyGo


    unkel wrote: »
    I took it to mean original capacity. So almost double that price to USD300 per kWh usable, which is far too high. Tesla Model S modules are around USD1000 for close to 5kWh usable, so USD200 per kWh. And far superior to the Leaf batteries and less likely to have further degradation at the same scale. Personally I'd aim for well under USD100 per kWh.

    Assuming a badly degraded mk1 leaf one has 12kwh usable, that would put a rough max target price of 1200USD for the battery.

    Longevity is certainly an important point for a someone seeking roi.

    Is the 200usd/kwh for used Tesla modules?


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,862 CMod ✭✭✭✭ unkel


    Yes. About a grand (USD) per module last time I looked

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



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  • Posts: 0 [Deleted User]


    Stick with lifepo4 (which leaf cells are) if going lithium road it's way easier find compatible hardware because you can adapt higher end lead acid legacy hardware.

    Tesla are NMC or something which makes "usable" capacity very hard to use. They're also super-volatile. Highly volatile ought to be enough for most beginners.

    It's the cell string voltages that make life easier or otherwise.

    Plyontech are best bang for buck.
    New cells CALB are best.
    Winston aka Thundersky are top tier
    as are Sinopoly.

    Buyer beware of Alibaba, shop around there's more knock-offs than genuine articles. Get serial numbers and check them.
    Deligreen are genuine resellers.


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