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Dala's Leaf buildthread (2015 Nissan Leaf)

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  • Dala's Leaf buildthread (2015 Nissan Leaf)

    So I thought I might start a project thread on this car, that wasn’t supposed to be a project.

    I recently picked up a commuter, 2015 ZE0 24kWh Nissan Leaf, with 5k km on it. It has extremely low range, the guess-o-meter(GOM) on the dash says 160km, but as soon as you start driving it you are lucky if you manage 20km. Pretty shite for 15 000€ (Yes these cars are extremely expensive in Finland!)

    Due to this being an USA model imported to Europe, so I apparently don’t have any battery warranties in place. I also wasn’t fully aware that the battery was this bad, so if I could go back in time I would have never bought this car.
    But nevertheless, let’s stay positive and start fixing this car up.
    Here’s a picture of the bog standard car. Not much to say really. Was a wet day.

    The car seems to deplete about 3-4kWh of battery, and then promptly report it as empty. This is strange, since it’s supposed to be a 24kWh battery! Charging it back up also goes suspiciously fast, so something is indicating that one or more cells are dragging the whole pack down.

    It also goes into turtle mode from time to time, and with a handful of dash warnings and load reductions.

    So next order of business is to start diagnosing the battery. The CAN communication needs to be forwarded to a phone running the LeafSpy Pro app. This is achieved with a bog standard v1.5 ELM327 Bluetooth OBD2 dongle. Note that it has to be v1.5, the cut down v2.1 won’t work.
    So here are some screenshots from a fully charged battery. Notice anything suspicious?

    So as you can see, the cellpair 57&58 are down 150mV from the rest of the cells. The Nissan battery management system utilizes passive balancing of the lithium cells using shunt resistors. Unfortunately, these are not very beefy, and can only bypass a few mA when charging. So if any cells have drifted far enough, and ESPECIALLY when replacing cells, you need to pre-balance them before you insert them into the pack.

    So a manual rebalance of 57&58 seems like the best way forward. Later down the line I can always replace them, but let’s start with a rebalance.

    First thing to do is disconnect the 12V battery in the front, or else the control system will freak out when I start disconnecting HW stuff

    Next thing to disconnect is the fuse from the HVDC pack. The fuse is located under the floor, and can be accessed via a panel in the backseat floor.

    After pulling the fuse, it is now safer to work under the car, and next step is to disconnect the high voltage cabling from the pack. Notice that I’m wearing Class 0 high voltage gloves each time I’m near anything labelled orange.

    Started propping up the car high with multiple failsafes.

    Removed splash plates. There are three of them.

    Here are the battery high voltage connections and CAN cabling, disconnected them. They were quite hard to figure out how to open.

    I then put pressure on battery with some wood and four jacks, started loosening bolts. There were 18mm, 8 in total.

    Built a dolly to be able to slide the pack around. The battery weighs circa 280kg!

    Lowered battery onto dolly

    Then it was very easy to slide the battery out

    For some reason they don’t want you to be able to open it easily. It was glued shut, but with the help of some prying and cutting tools, it eventually came apart

    Here is the battery exposed. Several stacks of modules, totalling at about 400V DC. Safety first, so gloves on at all times now!

    I then started to charging. Decided to take it slow due to not knowing much about the Li-MnO2 cells (I'm more of an 18650 guy ) Since the cellpair 57&58 was at the absolute bottom of the stack, they will be extremely hard to get to. I don't want to disassemble the pack, so I improvised some sticky leads with hard drive magnets inside alligator clips. That way I can just lower them down into the pack, and they will stick to the terminals.

    I then hooked up a bench supply, set it to 8.4V and connected it to the outer terminals of the 2S cell. I am lucky that the rest of the pack is at 4.00V cell average, so I won’t have to worry about CC/CV switchover, just CC charging up to 4V (8V effective due to 2S). As charge current limiter, I set it to 0.3Amps, to keep temps and everything nice and smooth.

    I also disconnected some of the BMS leads, don't know if this was necessary, and hope I don't break the BMS by piggyback charging this way.

    After 18h of charging, the cells are up from 3.60V -> 3.95V, so just a few more mV to go!

  • #2
    After charging the cell up and letting it sit for 16h, it unfortunately drooped back a few mV, indicating high internal resistance. It will have to be replaced in the future, but the car should be usable now, so I spritzed some bathroom silicone around the battery, and popped it back in to the car.

    I then plugged the charger back in, and tadaa, the blue dash charge leds lit up!

    The leafspy now reports a 46mV diff, heck of a lot less than 150-225 range before!

    The GOM happily reports a total 177km range now, but I need to just drive it and see what the actual range is.

    I took it for a test drive, and got 35km with loosing only two bars. That trip would have been impossible pre-surgery!

    Now I will start the process to try and get my hands on a good low-mileage Gen2 cell from another 24kWh leaf...


    • #3
      Did you re-glue the battery assembly together before you put back in the car??


      • #4
        Originally posted by ewat View Post
        Did you re-glue the battery assembly together before you put back in the car??
        Since I knew the cell is bad, I just used silicone sealant and relied on the remaining 10x10mm bolts to keep it shut and tight.

        Next time I have it open, I will use stronger and more glue.


        • #5
          While waiting for emails on potential cells,

          I decided to do my first mod! It's quite common in Finland to do grille blocks during winter, this allows the engine to heat up more rapidly and improve efficiency. But wait a minute, this is not an internal combustion car (ICE), so why do it to an EV?
          -It improves aerodynamics, no air will be forced into the engine bay. Leaf owners swear by this mod, claiming 1-2% more efficient km/kWh at highway speeds

          So here it is;

          I cut out some plexi, 70cm x 7cm, and attached it with zipties. I need all the extra range I can right now in this limited state


          • #6
            After completing the rough balancing, the car can now go 85km instead of 25km. Still really bad, should be closer to 150km. So the troubleshooting continues.

            I contacted a company that specializes in EVs, (EVs Enhanced), and they suggested doing a bottom balance instead of middle balance. This makes sense, since a balance in the middle of the State Of Charge(SOC) can be very imprecise. Making the cells bottom balanced will also help me in the future when I decide to swap the cell.

            So here are the instructions for how to do a bottom balance:

            1) Discharge the pack to a lowish point - the two cells will limit how far you can discharge of course
            2) Remove the pack again and re-open it
            3) Charge the two cells to significantly higher voltage than the rest of the cells in the pack
            4) Temporarily, reinstall the pack into the car and continue to discharge (lights/heater/etc on) until all the cells in the pack (except the two higher ones) are in the 3.0-3.3V range. This time the two cells wont be limiting your ability to discharge the pack
            5) Remove the pack and this time discharge the two cells to match the voltage of the rest of the cells - so they are all bottom-end balanced. Leave the cells to settle for a day after discharging to re-check the voltage and discharge further if required.
            6) Reinstall the back and fully charge it - if the two cells hit 4.12V while charging before the rest of the other cells then they are certainly lower capacity so replacing them would increase range to some extent. If other cells in the pack hit 4.12V before the two cells, then this replacement module has equal or better capacity compared to the rest in the pack - replacing it would give you no benefit.

            Let's get cracking!

            Assume the service position after draining the battery.

            Remove the pack again. Charging 57&58 up to 3.8V, when the rest of the cells are at 3.7V

            Start discharging again with the unbalanced ones at top

            Interestingly, when the SOC number dissapears from the dash, the car still runs the heater for over an hour! The heater pulls ca 3kW

            After completing the true discharge, the diffs are growing rapidly at close to 0% SOC

            While waiting for all this charging and discharging, I started cleaning the car properly for the first time.
            First thing to remove was the dealership stickers

            Much better

            Also waxed it for the first time

            I had also read threads about common issues. One of these was a faulty design in the shock absorber top mount, allowing water to pool on top of the bolt. This also affected this car and corrosion had started

            Dried it out and smeared some silicone sealant over it to make it waterproof. Very worthwile, some people even had reported failures here!

            So now I'm waiting for the pack to settle, and will continue with step 5&6 tomorrow.


            • #7
              So I finished the bottom balancing. Here are the results

              I was hoping to get a peek of the model number for the shitty replaced cell, but unfortunately it is below the visible sheet metal.

              Here is the car, fully charged. Note that it only goes to 83% SOC, limited by the shitty degraded cell that hits 4.1V before the rest.

              After driving it for 15km.

              After driving it for 30km

              Noticed that the fully charged GOM now says 140km instead of 180km. The bars are also lost quicker up top now (expected!) but should now be a bit more stable at lower SOC.

              This concludes manual balancing. Now the next step is to actually replace the module. The bottom balancing will probably squeeze out a few more km's, might even be able to hit >100km now, but cell replacement is inevitable.


              • #8
                So simple, but so complicated at the same time!

                Looks like a lot of extra work to get that cell replacement done
                I stripped my car out so much it now has 49/49 weight distribution.

                Project Diesel Tune:


                My new Daily HA36S Alto Works

                Martin's Kei to success



                • #9
                  I just went 80km on a charge with heat on, then the low battery warning popped up. But all is not doom and gloom, I got my hands on a cell!

                  It came from Italy, a company that specializes in conversions and home-brew scooter solutions. It was cheap, and SUPPOSEDLY low mileage.

                  Part number: 295B9-3NF0B QR 14520 07486

                  Before I just chuck this one in, it might be wise to capacity test it. Wouldn't be fun at all to put in the hours and end up with similar range.

                  Specs seem to point towards 0.3C discharge rate, so that's what I'll aim for. Only problem is, I only have 18650 capacity testers that are made for max 10AH batteries... Might be time to invest in some better testing equipment.

                  Originally posted by MHR1294 View Post
                  So simple, but so complicated at the same time!

                  Looks like a lot of extra work to get that cell replacement done
                  Yeah this is heaps easier to work on compared to my old turbo SR20VET engine!


                  • #10
                    Things looking up then if you're getting more range

                    I've never worked on any SR20's so I don't feel your pain, I'll take your word for it though hahaha tick tick tick tick
                    I stripped my car out so much it now has 49/49 weight distribution.

                    Project Diesel Tune:


                    My new Daily HA36S Alto Works

                    Martin's Kei to success



                    • #11
                      Nice progress Dala! I always thought work on electric cars was something for official dealerships. I'm amazed at how easy it is to drop the battery pack.
                      Last edited by TheCaptain; 23-11-2018, 04:57 PM.


                      • #12
                        Umm, EVNX??

                        Really sorry to hear this car has been a bad purchase for you, at least you are probably the best person in Finland to fix it!


                        • #13
                          Originally posted by MHR1294 View Post
                          Things looking up then if you're getting more range
                          Heck yeah, even in this limited state, I did 100km this weekend with the heater occasionally on, below freezing!

                          Originally posted by TheCaptain View Post
                          Nice progress Dala! I always thought work on electric cars was something for official dealerships. I'm amazed at how easy it is to drop the battery pack.
                          Yup, way easier than I thought, and way easier than internal combustion engines. Less parts == Less complexity

                          Originally posted by cubic_nz View Post
                          Umm, EVNX??

                          Really sorry to hear this car has been a bad purchase for you, at least you are probably the best person in Finland to fix it!
                          EVNX is progressing I just picked up more lithium, but I wont bother posting boring scavenging updates, I will post when I have something interesting ongoing Cheers!


                          • #14
                            So I've now driven 600km with the leaf, might give you guys a status update.

                            The charging situation is not ideal to say the least. Neither my apartment complex nor workplace wants to let me charge. So this leaves me with only public charging places (3x in my city) and the occasional visits to parents. Sometimes the public ones are temporarily unavailable (broken/occupied), so I am certainly paying the early adoptor tax. Not impossible to live with, but if you don't have home or workplace charging, I don't reccomend getting an electric car frankly.

                            So let's improve the situation. The Nissan branded charging cable that came with the car charges at a measly 8Amp. This roughly translates into 8km per hour added to the battery. This makes family visits long, since I need to spend ca 3-6h charging when visiting. Since that is way too much family time, I purchased the chinese Duosida 16A EVSE. It costs 200€, so quite cheap! (Original Nissan charger costs 800€!)

                            It works in exactly the same way as the stock one, but instead it draws 16Amps when charging. 16A is quite a lot from 240V AC, so you need to be careful where you plug this charger in, if it's a 10A outlet for instance you will trip the fuse. This cuts the charging time in half, so now I only need to spend 2-3h charging!

                            I haven't had time to measure the capacity of the Italy cell, so I just put a small load on it to make it closer to 7V resting voltage, which is way better than the 8.2V it shipped with.

                            So to summarize, love the car, hate the charging infrastructure. Man I would like a parking spot somewhere!


                            • #15
                              Charging infrastructure here is going crazy! we're putting chargers in the middle of nowhere hahaha
                              I stripped my car out so much it now has 49/49 weight distribution.

                              Project Diesel Tune:


                              My new Daily HA36S Alto Works

                              Martin's Kei to success