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My Custom Battery Box build for new Fatbike

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    My Custom Battery Box build for new Fatbike

    Hi All!
    First, my thanks to the many members of this forum who gave me the inspiration to construct my first Battery Box, for my first E-bike build! I have like many newbies, been reading here for a good few months, before buying my first new Fatbikes, for myself and my young daughter. Daughters e-fattie is up and running really well, and now is my turn to convert my bike to E-power..!!

    Having researched this and a few other forums on e-bikes, and the fact that my home is in the rice and sugar growing plains of NE Thailand, and the nearest proper hills are a few hundred km's away, I decided on a conversion with a 3000w Hubmotor, and as my nice new Fattie has only a small frame triangle, I soon decided that a custom battery box was essential to my plans.

    After detailed measurements of the volume available, I realised I had room to fit either 3 x 4s, or 2 x 6s 16000mah Multistar LiPo packs from HK, or I can squeeze in an 18650 30Q 14s6p em3EV triangle pack into my custom battery box. Either of the options are most suitable for my riding on the mainly hard pack trails through the surrounding farmlands at my home in this rural outpost in Thailand! Also, I am a fit, 65 year old guy, and am quite happy cruising around the trails and local roads at around 30 to 50 kph depending on conditions, and I like to pedal a bit as well, so I think these battery specs will suit me fine.

    Originally I had envisaged a made to measure frame bag, but seeing some of the nice creations on these pages, decided a custom built battery enclosure could be a lot more aesthetically pleasing.. I like things to look nice, as well as having good functionality..!

    One of the great things I have learned since living in Thailand for the last 12 years is the incredible number of uses that Thai PVC water pipe can have. Having built my home here 8 years ago, and designed and installed all the PVC water and waste pipes myself, I have a great regard for the versatility, availability, strength and ease of working this product exhibits. And it is very inexpensive, and can be hand formed into complex shapes with just a heat gun and bending springs.

    Having discarded the ides of 3D printing, because I don't possess a printer, or know anyone in my farming community that does either (plenty of buffaloes, cows, chickens, pigs and rice though,,!) and considering the use of aluminium sheet, my thoughts kept returning to Thai PVC pipe..something of a fetish, you may wonder..!!

    I have lots of PVC pipe in all sizes in my store, and a quick measure up revealed a 2" diameter pipe with 3mm wall thickness, cut in half lengthways, would produce a strip of PVC plastic 90mm wide..exactly the width I had in mind for my battery enclosure to accommodate 74mm wide HK lipo packs, with room for foam padding, and no problem with my bikes 120mm BB spacing.

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    Armed with my heat gun, jigsaw, tools and paper template of my bikes frame triangle, I soon set to work and in a few hours had formed a PVC battery enclosure frame that fitted snugly inside my bikes frame triangle, and was securely fixed in place by the water bottle 5mm bolts. I also will secure the front of the battery enclosure with an additional mount onto the downtube.

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    Having completed the outer frame, I was considering either using ABS sheet or plywood for the side plates, when my wife produced a nice sheet of 3mm thick Hardwood veneer board, donated to her by our village Buddhist Temple, which was perfect for cutting out 4 pieces for the laminated side plates I had in mind. Plan was for 1 inner plate to fit snugly inside the PVC frame, and the outer plate to fit the external dimensions of the frame. This would give a strong laminated 6mm thick plate, and improved weather sealing and appearance of the completed enclosure, I hoped!

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    I drew out the shape of the inner plate using the PVC frame itself as the best template, and jigsawed it to shape. Once both sides were cut and a good fit confirmed, I cut the 2 outer plates 3mm larger all around, check fitted for accuracy, then laminated the 2 pieces each for the left and right sides using PVA adhesive, weighting them down onto a large spare porcelain floor tile and left them overnight to dry nice and flat.

    The following day, the sides were laminated nicely and rest fitted a treat into the PVC frame..Mounting brackets were bent up from some more 3mm Flattened PVC sheet, measured up and drilled to fit the frame and attach the side plates. The mounting holes were tapped to accept 5mm bolts, so no nuts are required.

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    After the side plates were bolted in position, I sanded them to exactly match the shape of the PVC frame, and then gave them a few coats of polyeurathane lacquer until they had a nice, smooth finish.

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    The final job will be to cover the Blue PVC frame with Black Carbon Fiber 3D vinyl adhesive wrap, which I have on order from my supplier in China via Lazada online shopping. My original plan was to also cover the side plates with the Carbon Fiber vinyl wrap as well, but I am really liking the "Woody" look of the varnished side plates, so now I'll wait until the vinyl wrap arrives, cover the PVC frame, and judge the look before deciding to cover or not cover..

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    What do you think would look best..??!!

    Project Costs:
    1.3m of 2" x 3 mm PVC water pipe.......0.00 (£1.50 if you needed to purchase)
    100cm x 40cm X 3mm Veneer Board...0.00 (maybe £4.00 if purchased)
    24 M5 x 10mm Cap Head scews...........£3.00
    Laquere and Thinners.……......................£3.00
    150cmx60cm Carbon Fiber vinyl wrap..£5.00

    My total Cost............…...........................£11 .00

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    Great job, I like the exposed wood.


      Thanks Harold! Before I was given the offcut of Hardwood Veneer board by the nice Abbot from our village Buddhist Temple, I was planning to make the side covers from 2 Lams of 3mm plywood, and cover them with the Carbon Fibre vinyl wrap, same as I will use to cover the blue PVC frame.

      Now I have the nice wood veneer board, and have it all lacquered up I also like the look! I think I shall keep this finish and enjoy my modern version of the lovely "Woody"..!!


        I love the photo of the rolling pin. Does that PVC have any memory? Will it try to revert say in the hot sun? What is the thickness of the PVC and do you know of an equivalent in the US?


          Originally posted by calfee20 View Post
          I love the photo of the rolling pin. Does that PVC have any memory? Will it try to revert say in the hot sun? What is the thickness of the PVC and do you know of an equivalent in the US?
          Hi Calfee!
          Thanks for your interest, and good to talk to another ex "motor trade" man! My previous, pre-retired life in the UK was in Sales and Marketing with BMW, and although laterly in General Management I always had a keen interest and responsibility for the Aftersales area of the business. The technical aspects of cars these days is incredible, and the knowledge and skills required by the vehicle tecs grows by the day. Nowadays they are more electrical specialists than mechanical ones it seems!

          Onto my Battery Box, you mention one of my Specialist Tools I used in the construction.. This does admittedly resemble a rolling pin, but is in fact a high precision, materials flattening tool. Normally retained in my Wife's Kitchen tool store, I was required to undertake full technical training on the tool's use supervised by my wife, and after I was considered to be a safe and proficient user, and having been instructed on all the Health and Safety regulations pertaining to the tool's use, I was allowed to remove the tool from her locked tool store for my intended use...Hehehe ..!

          My wife demonstrating some proficient tool usage for my training..

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          Anyway, back to the serious Battery box stuff.. Hahaha..!
          Thai PVC water pipe is used everywhere in Thailand from the smallest home to large commercial buildings. It's available from every hardware store with a range of sizes and fittings that beggars belief! Easily cut with any hacksaw, and joined securely in seconds with inexpensive PVC solvent, it is a DIY'ers dream. You would not believe the number of products made from this versatile stuff.. Even E-Bike battery boxes..!!

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          The pic above shows me under the house floor, when building our Thai home and you can see some of the "designed" uses of Thai PVC pipe..

          The wall thickness of 2" diameter pipe is 3mm, and when the pipe is heated with a heat gun until just turning straw colour locally, it can be formed into a variety of shapes, without exhibiting any later weaknesses after cooling, and retains it's original rigidity and strength. It does not exhibit any noticeable softening in direct sunlight, remember it is designed for use in our hot, tropical climate! It is safe for use in hot water systems up to 80c and doesn't exhibit any real memory effects even when re-created with a heat gun.. It just goes back to a maleable state.

          I have only vacationer in the USA, so have no knowledge as to availability for yourself. I must say I never experienced this product in the UK. There we had a much more flexible pipe system, with screw on compression fittings, not at all like this rigid Thai PVC pipe and fittings.

          Hope this was of interest for you.. I always enjoy reading all of your posts, and love the Cruiser build.. Wish we had this bike in Thailand, but with 60% import duty, plus 10% local tax, plus 7.5% vat for anything shipped from outside of the ASEAN trading area, it would be a nice, but very expensive bike..!


          • calfee20
            calfee20 commented
            Editing a comment
            "The wall thickness of 2" diameter pipe is 3mm" Thanks this info gives me a lot to go on. I think I know where to look now.

          Omg really beautiully well done battery box that makes that DIY bike looks like a $6000 production bike.... nice work.


            Originally posted by Eric Luna View Post
            Omg really beautiully well done battery box that makes that DIY bike looks like a $6000 production bike.... nice work.
            Thank you, Eric!

            A lovely and very welcome comment from the man that makes the best, most affordable production E-Bike s on the Planet!

            It's not in the same league as your neat, integrated battery box fitted to the Ludicrous FS Fattie, but I am ​​​​pleased with the way my home made, simple box has turned out. I was planning to use a custom made battery bag from a UK supplier, but somehow the thought of all those velcro straps looping around my nice new frame and graphics put me off, encouraging me to try and make a neater, more integrated solution for my nice, new bike. I can't help it, but I like to have my " boy's toys" looking nice..!

            I'm looking forward to getting on with the e-power conversion, as soon as the ordered parts arrive, and I'll document the build for a later report.

            Sorry Eric, but I would have bought all my e-kit from Luna in a heartbeat, we're it not for the fact that living in Thailand the import duties and taxes add nearly 90% to the shipped costs for anything E-Bike imported from outside of ASEAN free trade area. Luckily for me, China is included in the area, so all imports are virtually duty free from there.

            You need to open a "store" based in SE Asia (like me in Thailand?!) and ship locally produced parts from that location, then you could enjoy the duty free sales of Luna products to the massive market in these parts..!

            Thanks again Eric, and Best Wishes to you and yours for 2017




              I really like the creative materials you chose, that's beautiful. Clearly hand crafted, and somehow a lot more inviting that way than if you had painted it or covered it. Especially appropriate for the tropics, I think. Makes the bike look quite at home there.

              Thanks for showing us.
              Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.


                Battery Box Completed..!

                I was delighted to receive my Carbon Fibre vinyl wrap from Lazada's courier yesterday, only 9 days from placing the order to a China seller on their shopping site.

                Opening the packet, all appeared fine as per their promotional material, and this morning I was anxious to get cracking on finishing my box build project. I had already removed the battery box from inside the bike frame, and washed and degreased it, ready for covering with the vinyl wrap, so I was ready to roll..!

                I marked out the strip of vinyl on the rear paper backing large enough to fit around the perimeter of the PVC battery box frame and with a few cm extra width and length to allow for "drift" and finishing around the frame edges.
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                Then it was just a matter of easing the backing paper away and gradually progressing around the PVC frame, ensuring the vinyl was adhered without any air bubbles. My wife's hairdryer was very helpful in heating the vinyl, and a enabling it to be stretched gently around curves, and folding over and sealing the edges securely.

                Very quickly the job was completed on the bench, and the battery box side panels clipped into position to check all was well.
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                Very happy with the finished results, I soon refitted the now completed Battery Box into the bike's frame, and stood back to admire the finished job. I am really pleased with how it has turned out, and hope you like it too..!
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                Now, can't wait for all the rest of my conversion kit, batteries, charger etc to arrive in the next few weeks from suppliers in China and Hobbyking as soon as the Chinese New Year holidays are over, so I can really get to grips with my conversion. At least I now have a nice home for the batteries ready and waiting..!


                  Originally posted by JPLabs View Post
                  I really like the creative materials you chose, that's beautiful. Clearly hand crafted, and somehow a lot more inviting that way than if you had painted it or covered it. Especially appropriate for the tropics, I think. Makes the bike look quite at home there.

                  Thanks for showing us.
                  Hi JPLabs,

                  Thank you for your comments, and I am delighted to read you like the box build! I think you are right about the look suiting the Tropical life the bike and rider both lead.. Somehow it wouldn't look so appropriate with a foot or two of snow and sub zero temperatures.. Something we shall never experience here in NE Thailand..!

                  Hope you like my latest pics of the finished project..!