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Dala's EVNX

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  • Dala's EVNX

    Hi, Im Dala, a 25 year old electrical engineer. It's time to start something new this year. After having lots of fun with my other project car, the 6-speed turbocharged, water injected Nissan NX, my mind is constantly looking for a new technical challenge. I think I have finally found it, I'm going to do convert a NX -> EVNX. I am really interested in EVs, since they seem to tick all the boxes youd want in a fast car, instant torque, blazing acceleration and minimal service needed. A Tesla here costs ~100 000Euro, A boring Nissan Leaf costs ~35 000Euro, so building your own EV seems like the best way to get into EVs. You might also learn something by doing it yourself. The plan now is to harvest most of the lithium needed from scrap 18650 cells, same type that is used on Tesla cars. Lets see how this turns out, since the most of the cost of an EV comes from the batteries, it seems like a logical way to save lots of money.

    As much as I would love to use the SR20VET NX, with its bulletproof 6-speed transmission for this project, I think its sensible to start small with a proof of concept. I scanned the classifieds for some time before finding a suitable chassis. I had only three requirements, but the first two were quite demanding.

    1. Shall be a GTI, so bigger brakes, discs instead of rear drums. Also the GTI has side skirts, which makes it look way better imo
    2. Shall not be a total rust bucket
    3. Shall be pre-OBD2, so <1995.

    If you are familiar with my geographical location, which is Finland, this makes that extremely hard. We salt the roads each winter like mad, so most NXs today are either Swiss-cheese or scrapped. This is after all a 26 year old platform. 2.0L GTIs were never sold in Finland, we only got the 1.6L, and so it has to be an import car. After many months of searching I found one. So, on to the victim!

    This is originally a 1991 SR20DE powered German GTI 100NX, imported to Finland in the mid-2000s. Perfect! It was taken off the road in 2013, after the previous owner blew the engine, and lost interest mid swap. No engine, Perfect! I got it for the price of 150$, quite OK in my book

    It has been standing for quite some time, so nature has taken its toll on it. Ill take that any day over a rusty but well used mess. If we pop the hood we are greeted with:

    Surprise, surprise. Nothing. Time to bring out some elbow grease, give it a wash, and push it into the garage.

    After washing it. Now it is time to start deconstructing it, and prepare it for a new drivetrain.
    The next update will focus on the fuel aspect, more precisely, lithium harvesting. Were gonna need a whole lot of these:

    So here is a rough checklist of what needs to be done
    -Harvest ~2000pcs of 18650 Lithium cells
    -Strip down car to barebones, remove fuel tank, exhaust and excess wiring
    -Rust proof chassis
    -Re-paint whole car
    -Update brakes/suspension components
    -Install electrical vacuum pump for brakes
    -Fabricate Arduino GPS speedometer, battery level instead of fuel level
    -Install 5-speed gearbox, fabricate mount for DC motor
    -Remove clutch pedal, remove throttle pedal
    -Install potentiometer throttle pedal
    -Install batteries into packs, insert packs into car, spacing them to improve weight distribution
    -Install charging port into fuel filler location
    -Install battery management system
    -Install fuses/shunts, impact relays
    -Install DC-DC converter for normal 12V system
    -Optional, fabricate heating element
    -Iron out bugs
    -Inspect & Drive
    I estimate this will take 2-3 years before fully completed, so buckle in for a long ride J I will try to document and describe the whole process as thoroughly as I can.
    Last edited by Dala; 03-01-2018, 05:28 PM.

  • #2
    Or you could buy a mangangled tesla or the like. I have a few cells you could buy but I just have to suggest looking into the tesla packs. They arent bad to work with and they are light.

    EDIT: Fiberglass panels for the win! Carbonfiber does not save that much weight but properly made fiberglass panels will keep you busy for a while. its cheap and you dont have to worry about salt.
    Last edited by Robert; 04-01-2018, 01:56 AM.
    Permanent rev limiter = the crank popping out to say ELLO!!!!


    • #3
      Okay let's go thru the process of harvesting some lithium. First step is to find some scrap laptop batteries / powerbanks. Then you gently smash them to pieces, and extract the 18650 cells inside. Just like this:

      Next step is to tear the cells apart from each other, breaking the spotwelds that they are attached together with. After that a quick multimeter check, to verify if the cells still have some potential to be charged. All cells that measure close to 0V are instantly discarded. Cells above 2.4'ish volts can be charged. I am using Nightcore chargers for the initial charge, 500mA charge per cell. Each cell takes anywhere between 0-5h to charge with this charging setup:

      When the cells are full, and measure 4.2V, they are set aside for a week. If the voltage drops rapidly after this week, the cell is considered a self-discharger and discarded for this project. Here are a few good cells that were salvaged from laptop batteries:

      Next step is to test the capacity, but more on that in a later post. Let's get back to chassi prep!
      First order of business was to make the trunk stay open without falling down. The gas struts weren't doing much after 26 years of service. I replaced one of them with an 800N unit, which worked perfectly

      With good access to the trunk, I can start to deconstruct everything down to bare chassis. I am doing a complete color change, so it has to be done properly. This gives me good room to fix small rust spots too!

      Something that felt really satisfying was to cut through the main engine control harness. Soo wrong but oh so right

      The amount of parts that are never going back on the car is growing fast! I found an old alarm system under the dash, a pair of sidecutters made removal swift.

      I deleted the powersteering for now. I just looped the inlet/outlet on the rack, hoping it will work as a start. It's always possible to add an electrically driven later on

      Prepare for lots of boring chassi-prep in next update


      • #4
        I love the part about cell harvesting and how you are testing them out. I learned several new things!


        • #5
          That's my goal here too! Learning new things

          So I headed out to the garage and pulled an all-nighter. The SR20VET NX is going into deep sleep, I drove it to another garage for long term storage the following day. This will clear up more area to work on, which is much needed.

          After stripping out the carpet, I couldn't help but stare at those unnecessary pedals.

          Much better. Who needs more than one pedal anyway

          The new 2018 Nissan Leaf has a one pedal mode, More on this here, I found it very interesting:

          But back to the EVNX, I am going for maximum weight reduction on this build. One good place to start is the sound deadening tar

          After a few hours of scraping the floor. The green waste bucket in the picture weighed so much after this, I expect to save roughly 15-20kg by doing this!

          Then I shifted my focus on the rear. Removing the rear bumper is mandatory, both for rust assessment and to prep it better for paint. No fasteners gave me any problems here, which was unexpected to say the least!

          With the bumper removed, I could reach under the car and remove exhaust hangers and heat shields. It was a rusty mess, the heat from the exhaust made all shields super crusty.

          Speaking about crusty bits, removing the side-skirts turned into an archeological dig. Very dirty!

          Seems like I got part of Germany right into the garage This was a solid 1kg of dirt packed under the fender on each side!

          With the side-skirts removed, I put the car on jack stands to raise it slightly higher than it would have been on wheels. This will help with the body prep, more tolerable to work on a higher car.

          Next step, the front comes off. This is soo satisfying to do on a B13 chassis... A few bolts were too rusted to save here, so had to break out the dremel.

          The main reason to remove the front, is to get access to un-paintable areas. Here you can see rust starting to form.

          Next step is to go and lend a MIG welder. Removing the panels exposed some really nasty bits in the rear, stay tuned for next weekend!


          • #6
            Didn't really get much done this weekend, only got 2h of garage time

            But some pics, first step of getting rid of rust is to strip it all down to bare metal. Wire-wheels are great at getting down in seams, angle grinders work great for large surfaces.

            After bare metal is achieved, gray zinc spray is applied to the most vulnerable spots. This process, cold galvanizing, greatly increases the longevity of metal. I really like the spray variant, it is really easy to get into seams. I have found that a generous application of Hammerite paint is not a bad idea, it seals everything up real nice. Only downside is that it costs quite much, doing a whole underbody with this stuff will cost a fortune!

            So to summarize, Underbody treatment;
            -Strip to bare metal
            -Zinc spray
            -Hammerite black
            -(Normal 2K paint+lacquer if area will be semi-visible)
            -(Stonechip if area is exposed to wheel-well)

            This was a great opportunity to remove the doors. They really get in the way otherwise, and will get repainted separately.

            Next update, probably more of this...


            • #7
              Time for an update. Here's the essential building block when making 18650 packs. The plastic-holder-building-block. These come in many shapes, and I intend to try out a few. This one consists of individual pieces that you snap together, to make any battery shape you want.

              When using it with cells, they look like something like this

              Another essential thing is a proper testing station. I did not opt for such, so I went with the more budget oriented 'Opus BT-C3100' It costs 25Euro, and you will soon see why it is budget.

              When testing the capacity of cells, you need to charge-dischare-charge the cell. After the discharge bit is done, the charger stores the capacity value expressed in mAh. As you might have noticed, I am only testing two cells at a time. This thing overheats, there's a tiny 30mm fan on the end of it, which is nowhere near enough to cool down the P=UI, 4cells x(4.2V*0.5A) = 8.4W of power it generates. Forum posts say that it thermally throttles and shuts down, which is catastrophical when the process takes 3-5h to complete. So to combat this, I added an 120mm fan directly under it. So far it seems good, I will make a permanent mount for the fan asap.

              But this all allows me to test the cells fully, and mark them with a sharpie according to their quality. Cells below 2000mAh are instantly discarded for this project.

              Back to the car. I further dismatled the windshield covers, exposing some pretty nasty bits.

              I wish I had some blasting tool. It takes forever to grind down the metal with angle grinder / wirewheel drills. After it is completed, I apply liberal amounts of zinc paint.

              After the zinc is dry, I can encapsulate it in proper metal paint. This looks sooo satisfying in person, makes it worth all the effort.

              Another thing that had to go was the gas tank. I had never previously removed one of these, so it was a bit of a learning experience. I ofcourse salvaged the fuel, and put it to use in my daily beater Getting rid of the fueltank makes welding the chassi much safer. Especially when I'm gonna be working quite near where it used to rest.

              After poking around on the right rear trunk section, it was rusted beyond repair. This will have to get welded.

              MIG time!
              Last edited by Dala; 05-02-2018, 04:47 AM. Reason: euro sign messing up forum post


              • #8
                Today a small package arrived:

                I am gonna be sourcing some of the lithium from a Polish guy, he sells already tested cells (2200-2300mAh range) for 0.91Euro per cell. Sweet! Here's my initial buy of 75 cells. I will take the skeptic approach and re-test some, but this looks very promising!

                Since a co-worker asked, I did some math on the battery weight compared to traditional lead batteries.
                2000 lithium 18650 cells weigh ~90kg
                5x big lead batteries with the same capacity would weigh ~380kg

                No one in their right mind would attempt this with lead batteries :P It is also more expensive to purchase lead batteries compared to recycled lithium batteries.
                Last edited by Dala; 09-02-2018, 05:16 PM.


                • #9
                  I received a massive shipment of NEW batteries. 18x HP CC09 containing 9 cells each. 8x Sikher batteries containing 6 cells each. They were really cheap, very pleased with the HP ones:

                  So here's everything on the bench. The total amount of new cells today is 162x Samsung, and 48x no-namers. I have now a total amount of ca 330cells. The bottleneck is now the Opus battery tester, seems like I will have to get another one (or even two more!) to get the processing sped up. It will take some time to get to 2000 cells by buying random packs, but it's the most economical way to do it.


                  • #10
                    Do you need to test all of the new batteries, or could you test a sample of 10%, and if all are good as new infer that the others will also be as good and don't need to be tested?


                    • #11
                      Totally possible, but I want complete guarantee that every cell is capable. I actually ordered two more testing stations to be able to cope with the volume.

                      Been working on eliminating rust this weekend.

                      The front passenger floor was quite corroded. Let's fix this.

                      Midway through grinding it clean.

                      After encapsulating it in thick paint. This small section took over an hour to complete, so it's not a fast process.

                      Backside is shaping up. All rusty parts have been scraped clean, zinced, and now painted.


                      • #12
                        I got another 2 Euro/laptop battery shipment, 16 random ones to tear down. I should now be in posession of about 500ish cells.

                        I'm always excited to see Samsungs, they always seem to be >2000mAh

                        I fixed the Opus overheating more permanently. I cut out the bottom plastic panel, and attached the 120mm fan directly to the casing with zipties. Now if only the rest of the testers would show up I'm starting to collect quite the backlog of cells to test

                        Some of the best cells I've found were rated at 2750mAh. Quite impressive considering the laptop battery they came out of looked quite used!

                        Back to fixing rust. Here's the before picture of the front chassis.

                        Interesting to find lots of Nissan stamps on random bits. They must have really enjoyed branding all individual sheets of metal back in the 90s.

                        I'm going for maximum weight reduction, removing the fog brackets from the front bumper bash bar.

                        And let's not stop there, I'll even grind off the mounting points for ultimate weight reduction.

                        Removing rust. It's even colder that it looks in the picture :S

                        I went ahead and cut the second wiring harness completely. Seen in bottom right corner. Now there are no electrical connections whatsoever left. Everything will be redone from scratch.

                        I then grinded and painted some more, but pictures will have to wait until next update, once everything dries. We've been hit with -25C, so keeping the garage warm enough to paint is a proper challenge. It consumes quite the amount of wood to keep the floor heating loop warm enough. A minimum of +10C is needed for the thick paint to dry, and I'm barely reaching +8C...


                        • #13
                          Today I went back to the garage after work. Still sitting at -24*C when the sun goes down. My dad's on winter vacation and been keeping the fire going. It's the only way to be able to get paint to dry at this time of year.

                          Before I inspected the paint, I dropped off today's haul. I had stopped by a PC repair company, and got 11 used 'HP 6cell' packs for next to nothing. Hoping to make it a regular salvage location, fingers crossed

                          Back to the car, this is the freshly coated and lightened bumper bar.

                          And here is the front. Feels good to see progress.

                          Here is a section i treated in a different way. The visible parts wont get that thick brushed on paint, here I applied normal gloss spray paint. No more relay boxes here either

                          Remember the nasty windscreen cowl? I thoroughly cleaned it out, and applied a nice coating of Rostex. The intake air for the cabin is gonna be so fresh, with no more dirt mixed in it

                          Now I really need the extra Opuses...


                          • #14
                            Been slacking off a bit, since the weather is so hostile. Anyways, here's what arrived in the mail last friday. 800grams of plastic cellholders. This is the 4x5 variety, should be more sturdy for automotive use

                            After unwrapping it and cleaning up the bench a bit. I noticed most people stack untested cells in some type of shelf. Seems to be very space efficient

                            I also tried reviving some dead cells. Anything above 0.1V, but below 2.0V is considered dead by most chargers. The Nightcore chargers flash these cells as 'EE' on the display, and simply wont charge them.

                            However, the Opus can slowly nudge them back to life, by carefully charging them at 1-50mA, and bumping it up to 200mA once they pass approx 2.2V. It is important to slowly restore these dead cells, atleast most of forum posts seem to say that rapidly charging dead cells will make them loose most of their capacity. After reviving these cells, they landed at 1600mAh, still too bad to be used in this project.

                            But a purpose they will have. I am starting a separate project for the cells that fall in the 1500->2000mAh category, they will power our offgrid summer cottage situated on an island in the Finnish archipelago. Might even have to make a separate thread for it

                            I just briefly went into the garage, and unbolted the fenders from the front bumper.

                            There was quite some rust lurking under the front lower lip spoiler. This would have quickly turned them into swiss cheese untreated!


                            • #15
                              This is totally out the box, really like it man, keep the updates coming.
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