Energy Storage System Using a Salvaged Leaf Battery


One could use a salvage battery pack from a Tesla or a Volt. The only problem is that those packs are liquid cooled and who wants to mess with that for an ESS (energy storage system).

However, Leaf modules are perfect for an ESS. Each Module has 4 cells with 2 hooked in series. Put 7 of these modules together and one has 48 Volts. They make a really sano ESS as shown in figure 1 and 2.

Editor’s Note: This article is credit to the Nissan Leaf Forum. The particular post is from a gentleman in Norway with the handle offpist. So hat tip to “offpist” for letting us share it.

Rack Of LEAF Batteries (Fig 1)

Rack Of LEAF Batteries (Fig 1)

Fig 2

Fig 2

The handy Norwegian used a server cabinet to mount the cells. The cabinet has a glass door and cooling fans on top as shown in figure 3.

Cooling Fans Help Regulate Temperature (Fig 3)

Cooling Fans Help Regulate Temperature (Fig 3)

Not all of us live in California that has great TOU rates for putting kwh’s into the grid during peak. In fact utilities are on a campaign to charge more for using the grid as a storage battery. Here in Arizona, my utility has just started charging for Net metering – although the Arizona utility commission scaled back their rate request from the original  $120/month they wanted to charge. In addition my utility now pays me only 2 cents per kwh for banked kwh’s I have not used at the end of the year.

All utilities in the US are not the same. One on the writers here (Mark H) has a looming end to his good net metering rates and is also seriously considering a big battery for his PV system as a result.

If one could pick up a good deal on a salvage Leaf pack then one could have a dynamite little ESS for less $/kwh than lead acid. The person in this case paid $2,000 for the whole pack so on a per kwh basis the energy storage is very reasonably priced (even less than lead acid).

Of course the devil is in the details. You also need lots of other stuff to create your AC coupled “Island” as show in figure 4.

SMA System (Fig 4)

SMA System (Fig 4)

Personally, I would like to make a smaller version of this ESS. I think around 6 kwh’s would be perfect for a portable battery/ inverter system used for emergency power. I am seriously considering this as a compliment to the DC tap I explained in a previous article “Getting your Solar Array to Work when the Grid is down”.

What do you readers think? Is this a cool thing to do with salvage Leaf batteries? I think it’s a slam dunk answer yes.

Cheers Leaf Heads   ☺

Category: General

23 responses to "Energy Storage System Using a Salvaged Leaf Battery"
  1. Rik1 says:

    Tesla batteries need liquid cooling to handle charging rates up to 120 kW and discharge rates up to 320 kW.

    Liquid cooling is apparently not needed for Tesla batteries in home energy storage service, which involves much lower power rates.

    Here’s an example of an 85 kWh battery from a wrecked Model S being set up for off-grid solar storage. With no liquid cooling, FLIR measurements showed that the re-purposed battery modules had almost no change in temperature even after an hour discharging at 18 kW.

    1. GeorgeS says:

      Very cool.
      Thx for the link.

      Looks like he is 400 or so VDC as input to the inverters.

      The SMA island inverter in this article takes a max of only 48.

      More DC Volts cuts down on wiring cost.

      1. Rik1 says:

        The re-purposed Tesla 85 kWh battery storage is 44V nominal.

  2. GeorgeS says:

    Let me add that the OP now has 70 modules stuffed in that cabinet for a total of 35 kwh storage.

    He got another salvage battery for only around 400$.

    1. Mark H says:

      This is what I like. Let George do all the work and reap the rewards.. Good on ya George!

      1. GeorgeS says:

        Thx Mark H.

        I know you were thinking Tesla pack but I’m not sure the Tesla Batts have enough cycle life.

    2. Rik1 says:

      Wow, so he’s only spent $2400 on battery modules to get 35 kWh of storage? That’s a great price.

      1. GeorgeS says:

        I should retitle the story too:

        Dirt Cheap (Yet Quality) Energy Storage System using a Salvage Nissan Leaf Pack”. LOL

  3. BraveLilToaster says:

    I can’t help but wonder if it even needs to be this complicated. I know that many solar panels come with inverters to convert the DC voltage from the panels to AC voltage for your house, but I see two inverters here when it shouldn’t be hard to match the battery voltage to the solar panel output voltage. Wiring a single inverter in parallel to this system should ensure that only power not used by your house goes into your batteries.

    On top of that, there should be hardware built into the Leaf that you can use for voltage regulation, battery balancing, charging, and all that fun stuff (which is usually a pain in the butt for people building their own batteries). There’s little doubt that the salvage yard where the batteries came from would be happy to let you pay for these items too. You might even be able to score the hardware that lets you monitor the state of charge, plus that touch-screen that ties it all together. 🙂

    Or maybe I’m wrong and I don’t know what I’m talking about. It’s the internet after all. 🙂

    1. GeorgeS says:


      Not a bad idea actually.

      If one had a Micro inverter type system it puts out 220V. Then use the salvage Leaf on- board charger to charge the pack. It’s designed for 220 input.

      1. BraveLilToaster says:

        No, I was thinking more that you could use the 400v DC quick charge circuitry, so that you wouldn’t see any losses from converting from DC to AC to DC again, then *again* when you have to convert the pack voltage back to AC when your house needs power at night. The losses in converting back and forth like this would be considerable. It’s far better to use DC until you need AC.

        The on-board charger always converts power to 400v DC (or maybe that’s 380V?) for input into the pack.

        1. GeorgeS says:

          Hmmm yes. Just pump up the solar panes to 480.

        2. Mike I says:

          You don’t know what you’re talking about. The way “Offpist” designed his system is the most technically sound way that there is. The problem is that LiIon batteries need different battery management. His solution handles that properly with a BMS that talks to the Sunny Island over CAN-bus. Conventional Off-Grid solutions have a single inverter and use the DC from the solar to directly charge batteries. They do the Max Power Point Tracking (MPPT) properly, but they float the batteries at a fixed high voltage designed for lead-acid. This is not good for LiIon batteries.

          1. GeorgeS says:

            @Mike I

            Don’t get me wrong. I think the OP did it very well. The TMS is cool.

            We are just speculating that it might be nice just go right from the Panels to the battery without any conversion losses.

  4. kubel says:

    We’ve got two cabinet mounted PbA battery backups in our datacenter to provide intermediate power to cover the time it takes for our ATS to kick over to generator power. They cost a hell of a lot more than $2000 each and have very low energy density and capacity (only about 20 minutes worth of power for four host cabinets and two VMAX cabinets).

    Someone should source used LEAF packs and start producing a product for environmentally conscious corporations and home owners. I can say that wheeling a massive cabinet full of lead acid batteries up a ramp into a floating-floored datacenter is not fun.

  5. Jouni Valkonen says:

    Deep charge Lead acid batteries are not particularly cheap for energy storage solutions. That is because they have low cycle life even with 50 % DOD. 50 % DOD in practice doubles the cost per kWh of Lead acid batteries compared to their name plate capacity.

    In additions there are concerns with low efficiency, low calendar life and often need for maintenance and need for ventilation due to hydrogen leaks.

    Therefore in practice lead acid batteries are about twice as expensive as ferro-phosphorus lithium ion batteries. And for this ultra cheap salvaged do-it-yourself energy storage solution, we really cannot even compare the prices!

  6. FSJ says:

    My big question is, where are you going to get a charge controller for the Li packs? Lead acid controllers abound, but I have never heard tell of a commercial Li pack controller that isn’t in a car.

    1. GeorgeS says:

      I think the charge controller is in the Sunny Island inverter but I could be wrong.

      I believe the OP didn’t need a separate charge controller.

      1. FSJ says:

        I’m very skeptical, George. Grid tie solar inverters don’t have charge controllers because they don’t have battery backup. Grid tie with battery backup systems have charge controllers. But there aren’t very many grid tie with battery backup systems out there, and I’ve never heard of one that is Li ready. My Outback does not have integral charge controllers. They are separate. Also, you HAVE to have a charge controller. The voltage from the panels varies like crazy, all day long based on temperature, insolation, etc. You can’t just send that straight to your batteries. You have to give it to them the way they like it. There must be a charge controller in between. And it has to be set up for Lithium. Someone in the comments mentioned OPs BMS, battery management system. What is it and where did it come from?

        1. Trond Arvid Røsvik says:

          The BMS used is this one:

          The Sunny Island supports Lithium but only when used with an BMS. Its an very safe and good solutions.

          My next project is to install modules from two batteries in an 44`sailboat, also in an 48 V setup. It will have 40 KWH usable storage, and weihgt about 400 kg. There will be 48V (981W) solar, 48V (400W) wind and engine alternator(1400W). Then i can have 48V->12V inverter for the regular stuff like lighting etc. Why 48V, not 12V? It just makes more sense when used in high power solutions. I want to be able to use washing machine etc also when on the anchor.

          Aslo i want to be able to charge up to 4600W when i have access to shore power. I this way i can top up in just one night.

          If i had a 12V battery i whould have to charge 2300A to get the same effect.

          After this thread i managed to get a hold of two more complete batteries. One for $1200 and one at $750.

          1. GSP says:

            Thanks for the link to the BMS. Your battery project looks to be very well designed and much, much, nicer than standard PbA batteries that are usually used in this application.

            Thanks for sharing with us.


          2. GeorgeS says:


            Thx for checking in.

            I can’t seem to find a charge controller for these Leaf Li batts.

            My solar panels are 200 W each, 40 Vfl and 5 Amps fl amps. 6 panels for 1200 watts. I would probably use 7 Leaf modules @ 48 VDC (3.5 kwh).

            I can’t seem to find one and I’ve spent a fair amount of time looking on google.

            Any ideas??

  7. bennyd says:

    I’m confident Tesla with it’s new giga factory will also creat a disruptive grid solution for the masses. As states like Arizona do all they can to discourage renewable energy solutions, tesla will offer a solution.