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    custom triangle battery box

    hello guys,
    i am building my first ebike. my original bike is about 11 years old, now comes the time to convert it.
    i will use bafang bbshd drive. i want to use lipo batteries. the problem of used bateries is their format. i will use 4x6s 12ah or 4x6s 16ah.
    the width of the box - on the picture needs to be 80mm +2x2mm wall thickness. my bottom bracket is 68mm.

    question - will i have problems banging my knees to the box, or is it okay to have box cca 84mm wide

    question 2 - is it worth to have 2kg more and have 8ah more

    thanks for answers,

    miso, slovakia
    width how will it looks like

    #2
    My battery is about 80mm wide and I have no problem with the width. The BBSHD will increase your pedal width. Measure across the BBSHD, I seem to remember around 100mm. Anyway you shouldn't have any problem with that width.

    More amp/hrs is always better. I don't know how to stress this enough. You will travel 3 times farther without even thinking about it. 13 amps and less = range anxiety. Somewhere around 20amp/hrs is really ideal. More is always better when it comes to ebike batteries.

    Comment


      #3
      Thank you calfee,
      now its fabricated from aluminium 2mm. looks like the width is OK.

      Now i have question. Which circuit brake should I use? I have found something on aliexpress - I have ordered the white type - non waterproof.

      As I will not have a service opening in the battery box, I need the circuit braker to stick out of the box. I am afraid of the rain then.

      How are you guys solving this?

      Many thanks,
      Michal


      Comment


      • calfee20
        calfee20 commented
        Editing a comment
        I don't have one. I am relying on the BMS to trip in case of a short.

      #4
      My temp solution is to close the circuit breaker to the box. No weather problems... and instead of switch i will disengage the plug everytime. lets see how it will work.

      Comment


        #5
        Looking good. Is that box welded?
        Robert

        Comment


          #6
          I don’t use a fuse.
          My XT90 connectors vaporized whenever I had a short.
          Usually from soldering the B- and B+ backwards on one side (on those long nights of building without sleep for 24 hours)

          Comment


            #7
            My next project is an aluminum shark case and a locking aluminum triangle case
            I was looking at some drawer sliders at Lowe's that would be perfect
            I don't plan on including the battery connection into the slider system

            I've built custom aluminum boxes with hand tools its not that hard
            https://makezine.com/2011/12/07/bend...omemade-brake/
            http://www.instructables.com/id/A-ri...-box-with-lid/
            Last edited by Robert Larrison; 01-11-2018, 01:36 AM.

            Comment


            • misko903
              misko903 commented
              Editing a comment
              It is not so hard, but you need to have a bend tool for roughly 600€ and a workshop :/
              My setup would be too heavy. 8kg batteries. Maybe half of it and shark case as you said... It will look much nicer.

            #8
            Originally posted by Robert62 View Post
            Looking good. Is that box welded?
            Robert
            Yes, welded by local welder. Cost me 70€. I will glue it into the frame.

            Comment


              #9
              Chainwheel changed from original Bafang 46T to Luna 42T. Well... to say tomething about Luna Eclipse:

              Pros:
              - looks sexy
              - weight half
              - big teeths does not allow chain to drop

              Cons:
              - Lekkie is lighter
              - I need to use the spacer, because the chainring was touching the frame -> offset 24.8-3.3=21.5 vs Bafang stock 19 and Lekkie 20.4
              - Paid roughly 130€ including import taxes, Lekkie is cheaper
              - For the price of 130€ I still need to visit several hardware stores to find specific allen key stainles steel screws (used the spacer). Does it cost Luna so much to add 5 screws more to the set with spacer?

              I have not tested it until now, as the weather outshide is ugly

              The circuit breaker will stay in the box.

              What about the SWITCH?

              Is anyone using any suitable switch on the box?

              Michal

              Comment


                #10
                Originally posted by misko903 View Post
                Chainwheel changed from original Bafang 46T to Luna 42T. Well... to say tomething about Luna Eclipse:

                Pros:
                - looks sexy
                - weight half
                - big teeths does not allow chain to drop

                Cons:
                - Lekkie is lighter
                - I need to use the spacer, because the chainring was touching the frame -> offset 24.8-3.3=21.5 vs Bafang stock 19 and Lekkie 20.4
                - Paid roughly 130€ including import taxes, Lekkie is cheaper
                - For the price of 130€ I still need to visit several hardware stores to find specific allen key stainles steel screws (used the spacer). Does it cost Luna so much to add 5 screws more to the set with spacer?

                I have not tested it until now, as the weather outshide is ugly

                The circuit breaker will stay in the box.

                What about the SWITCH?

                Is anyone using any suitable switch on the box?

                Michal
                I would choose the 125V breaker over the 12V one. Higher voltages need more careful design to prevent arcing when contacts open under current. Further, is that 125V AC, or DC? Needs to be rated for your DC voltage, you can't substitute AC gear. AC can self-extinguish arcs better, since it's turning on and off.

                I bought a marine DC rated breaker to use as both protection and switch, but decided I didn't need the switch feature, so didn't install the breaker, either. I also rely on BMS for short protection in the large power wires.

                I DO use fuses for my pack level accessory circuits, though. To protect the wiring and thus to keep my bike/shop from burning down in case of short. A short in thin wires may not pull enough current (60A, etc) to trip the BMS before the wires get white-hot and then melt, probably with arcing. That's obviously worth taking precautions.

                Hope that helps with your decisions.
                Last edited by JPLabs; 01-19-2018, 03:20 PM.
                Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

                Comment


                • misko903
                  misko903 commented
                  Editing a comment
                  Mine is 125V DC circ. breaker. Do you have a picture of your marine c. breaker?*
                  I don't use BMS, I will balance the batteries manually with balancer.
                  Which BMS are you using, or which you recommend for my setup?*
                  Are you using a ground to the chassis?*
                  ​​​​​​​M.

                #11
                Mines a Luna triangle pack and BMS.

                NO! No chassis ground. Certainly not.

                This is the breaker/switch. It is designed to be used as a switch, too, as opposed to many breakers. Note AC rating 250V, DC only ranges from 36V to 65V depending on the model, I think. Versions to 50A. Again, have not used it so not personally tested, but looked good on paper and looks quality in person:

                https://www.bluesea.com/products/cat...r_Style=Toggle



                Click image for larger version  Name:	51w5KoDHtwL.jpg Views:	1 Size:	38.4 KB ID:	56194
                Last edited by JPLabs; 01-21-2018, 08:40 AM.
                Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

                Comment


                • misko903
                  misko903 commented
                  Editing a comment
                  Thanks for the picture. Seems to be not waterproof too. I am wondering if we are pioneers of electrobiking, that the proper solution does not exists.

                #12
                Right, it's American Yacht Association approved, or what. But no IP rating. I'd say, not waterproof, but ought to be OK for damp environment s.
                Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

                Comment


                  #13
                  So I put the Alu box (only half of it) into a carbon foil. Pro - looks much better, Con - attract more sun - batteries will become more hot during summer days. I bought few of these screws dedicated to furnitures. Planning to connect the boxes with the screws.
                  Any idea how to seal the box? I need to open it from time to time to balance the batteries and to check if the moisture does not get in.

                  M

                  Comment


                    #14
                    Weatherstripping from the hardware store is one easy way, for a removable panel.

                    I find weatherstripping is too thick and not sticky enough. I like to use thin foam rubber mat, such as cheap toolbox drawer liner. Cut one big gasket. Attach with contact cement. Both sides, let it dry. Press in place.

                    Then wax the unglued side, or wipe with silicone, so it comes off easily after being clamped to the box a while.
                    Last edited by JPLabs; 01-31-2018, 04:10 PM.
                    Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

                    Comment

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