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  • #16
    Originally posted by calfee20 View Post
    When I put my bike together the BBHSD from Luna had nice beefy 10 ga wires but the slimline battery leads were a skinny 14 ga. This worried me even though I kept telling myself the battery people must know what they are doing. I found this calculator online that eased my fears. http://www.electriciancalculators.co...cond_size.html

    Evidentially DC is considered the same as single phase AC. So enter 48 volts dc or if you want to increase your margin of safety enter 120 volts 1 phase. I used a max of 30 amps and a 3% voltage drop. The only wires I was worried about were the battery leads that were less that 2 feet in total length so I entered that and hit calculate. As you can see for short lengths of wire surprisingly small gauge wires can be used.

    It took me a while to find this calculator again so I am putting it in my favorites. Another thing you should remember is that electricity flows down the surface of the wire and it only flows through the wire when the amps get toward capacity. This is why finely stranded wire will carry more current than stranded wire. My battery wires were very finely stranded. While playing with the calculator you can see that even 120 volts, 30 amps, and 10 feet of wire was still OK with a 14 ga wire.
    Thanks for that. Useful stuff!

    I think Luna is one of a handful in the industry that is attempting to push the standards on this. While smaller gauge wires may do in theory, when they get cruddy, the efficiency drops way down. A friend does solar install, and he always goes up one or two sizes for recommended gauge. The thing is, under average conditions, a 14 gauge wire may do the trick. Cover the stuff with oxide and you're turning valuable battery energy into heat. It really doesn't cost that much more to make things bombproof. As funwithbikes said, a lot of the engineering is done on a home lawnmower scale --- while better engineering costs more than the average user wants to spend. As a DIY builder, you can build to any standard you want.
    Last edited by Canuman; 03-18-2017, 05:32 PM.

    Comment


    • calfee20
      calfee20 commented
      Editing a comment
      I agree with you but in my case once I did the research I realized upgrading the factory battery wires wasn't worth the effort.

  • #17
    The electrical tools I have used as a mechanic and motorcycle enthusiast. I have picked up a few special tools to make my work easier over the years. My first dealer level job was with VW, Porsche, and Audi. This was a real training ground because they had horrid electrical systems back in the 70's.

    The first kit I bought was a VW item that would service any European car with Bosch components. It also worked somewhat on American and Japanese products. I totally refabricated a 75 Norton wiring harness with this kit to remove any trace of Lucas "The Prince of Darkness" from my bike. I have had many years of trouble free service from this electrical system and that is not a common thing for 70's English products

    .
    Click image for larger version

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    This crimper made a double crimp. One on the bare wire and the other on the insulation to provide strain relief. Note the two common connectors and the VW part number.

    Click image for larger version

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    Here is the whole kit.

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    • #18
      The first decent crimper that I got for the common insulated butt connectors and male & female spades that come in red blue and yellow is based on a vice grip style plier. I could never rely on a connection with these connectors until I got this tool.

      Click image for larger version

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      Note the three colored circles on the lower jaw to show the location of proper crimp. This tool was replaced with a more versatile tool with different jaws. I still use the older one most of the time though.

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      • #19
        To crimp heaver wires into solid copper lugs and battery terminals you need something that resembles a bolt cutter.

        Click image for larger version

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        That huge crimper is really for battery terminals but it can also do those smaller lugs that are rated for 6 ga wire. The ratcheting crimper in the box can also do those lugs but that is about max for the tool.

        Here is a final photo of the hardware store inside my toolbox.

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        • paxtana
          paxtana commented
          Editing a comment
          wow that thing is huge!

        • OptimusPrime
          OptimusPrime commented
          Editing a comment
          That's what she said.

        • Rider
          Rider commented
          Editing a comment
          WOW! I bet you are the local kids favorite neighbor. My father was in the Aerospace Fastener business and our garage was the local fix anything shop for the neighborhood when I was a child. We even kept a clipboard for tool checkout. Any of the kids could checkout a tool as long as they logged it with a date, time and name so we knew where it was if we needed it. Good times for creative kids on a budget...

      • #20
        Generally speaking I get better results crimping than with soldering but I have spent considerable money to accomplish this. One of the biggest problems when soldering is poor preparation and the wrong sized soldering iron. A soldering operation should be relatively quick so the solder doesn't have time to wick up the wire strands and stiffen the area of the connection. I have multiple soldering irons, so maybe I should take a few more photos........calfee
        Last edited by calfee20; 03-24-2017, 07:12 AM.

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        • #21
          +1. It is a matter of choosing the right tool for the job and practice. practice, practice :)

          Comment


          • #22
            I contacted Posi-lock about their current rating and they said it was fine for high current, figured I would test it out and see if it's something worth recommending for noobs, since a simple reusable solderless connector sounds great in theory.
            Results were mixed. I want to like them but there are several issues.
            • no step-down connectors for 10-12 to 14-16. Forget connecting xt90 or large bafang power wiring to generic hardcase cradles with this
            • no water resistant connectors in 10-12awg, only separate ones for 10 and 12 (and not even that for their most waterproof version)
            • while the connectors are billed as being reusable the below picture shows the seal degrading after a single use
            • no included package info showing the connector's not meant to be screwed back in all the way after wire insertion (admittedly a minor issue but overtightening will strip the threads)
            • the wire has to be cut to a very specific length or it does not work well
            • forget about screwing these in by hand despite the included pictures, you probably want a couple pairs of pliers if using on ebike power cables


            The 10awg water resistant posi-seal below was not great for standard 10awg xt90 connector cables. While the wire fit, there is a silicone gasket in the hole that is nowhere near wide enough to fit the wire insulation through, so you have this awful space between the wire insulation and the connector insulation where the wire's just exposed, see pic two. Not sure if they expect people to drill out the seal or if they did not make any allowances for the thick insulation used in large wires? Either way it's sloppy.
            Click image for larger version  Name:	IMG_20170401_210955.jpg Views:	1 Size:	182.9 KB ID:	31937
            Click image for larger version  Name:	wont fit insulation.jpg Views:	1 Size:	157.0 KB ID:	31938
            Had better results with the regular type posi-lock, which they have a 10-12awg for. This is important since many xt90 pigtails are 10awg, bbshd controller power wires are 12awg.

            As seen below the 10awg wire can enter the connector enough so there is no exposed bare wire at the edge of connector. So the non-waterproof connectors appear to be substantially more safe for noob use compared to the waterproof kind, if the waterproof kind were left unmodified and they just followed the directions on the package.
            Click image for larger version  Name:	IMG_20170401_211627.jpg Views:	1 Size:	153.4 KB ID:	31939
            Click image for larger version  Name:	xt90 10awg motor 12awg.jpg Views:	1 Size:	1.43 MB ID:	31940
            But these regular version connectors are not even slightly weather resistant, which would be very problematic for long term ebike use. Fine, we'll use some liquid electrical tape and dielectric grease.
            Click image for larger version  Name:	IMG_20170401_230249.jpg Views:	1 Size:	152.8 KB ID:	31941


            yay for permatex
            Click image for larger version  Name:	IMG_20170401_224842.jpg Views:	1 Size:	252.9 KB ID:	31942


            greasing inside connector
            Click image for larger version  Name:	IMG_20170402_212157.jpg Views:	1 Size:	181.9 KB ID:	31943


            LET waterproofing the connector
            End result not bad after modification, tested with a 50A peak controller and they didn't even get warm. And with the modifications it is definitely waterproof..But the connector is no longer reusable, it took a bunch of extra tools, was finicky and took a bunch of time. Even if you were to drill out a posi-seal gasket instead of these mods that still requires more tools than just using a lighter and a cheap heatshrink solder sleeve, and would probably be less sealed.
            TL;DR: Kind of defeats the whole point if it is neither simple, quick, easy, or cheap.

            Comment


            • funwithbikes
              funwithbikes commented
              Editing a comment
              Excellent write up! This was not the typical, 'I heard X, Y or Z was good (or bad)' like we see on some other forums.

            • paxtana
              paxtana commented
              Editing a comment
              For what it's worth I think this would be a very good connector for smaller wiring.

          • #23
            This is a great thread! I am very curious to try some of the shrink with solder inside, novel idea, my only concern would be using a flame to shrink it, I much prefer a heat gun, more bulky, but much easier to control the temperature and avoid over-heating/burning of the shrink. I also really like using marine grade shrink with adhesive inside, the regular stuff will just get loose and move over time.

            Anyone tried the self-soldering shrink on a high watt application? I guess worst case scenario, things would get hot enough if your wire was too small/lacking quality for the load and the solder would liquefy, but if the shrink is high enough temp, perhaps it would survive a momentary heating in a short burst, but of course, if you over-size the wiring in the first place, shouldn't be an issue.

            I am thinking when I am able, and can really have the kind of power to push my Cro-Motor at a race track, that I would probably be ok running 72V 100A through 8g wire, main problem then is either a very expensive BMS and large 18650 battery, or just a good set of LiPo (Turnigy Nanotechs are my favorite so far, LiCo seems to perform well as long as you don't abuse them) and deal with the annoyance of balance charging a pack that is only used on a race track on occasion.

            Comment


            • #24
              Good to see this thread taking off. I haven't done much with e-bikes in the past few weeks, but I did deliver some red-hot peddle builds Once a bike wrench, always a bike wrench. Working on my own "fat man on an e-bike" build, and have got some significant parts sorted. My son calls it "The Japanese Gangster Mafia Sketchy Bike." I think that I'm pleased with that.

              Comment


              • #25
                Originally posted by paxtana View Post
                I contacted Posi-lock about their current rating and they said it was fine for high current, figured I would test it out and see if it's something worth recommending for noobs, since a simple reusable solderless connector sounds great in theory.
                Results were mixed. I want to like them but there are several issues.
                • no step-down connectors for 10-12 to 14-16. Forget connecting xt90 or large bafang power wiring to generic hardcase cradles with this
                • no water resistant connectors in 10-12awg, only separate ones for 10 and 12 (and not even that for their most waterproof version)
                • while the connectors are billed as being reusable the below picture shows the seal degrading after a single use
                • no included package info showing the connector's not meant to be screwed back in all the way after wire insertion (admittedly a minor issue but overtightening will strip the threads)
                • the wire has to be cut to a very specific length or it does not work well
                • forget about screwing these in by hand despite the included pictures, you probably want a couple pairs of pliers if using on ebike power cables


                The 10awg water resistant posi-seal below was not great for standard 10awg xt90 connector cables. While the wire fit, there is a silicone gasket in the hole that is nowhere near wide enough to fit the wire insulation through, so you have this awful space between the wire insulation and the connector insulation where the wire's just exposed, see pic two. Not sure if they expect people to drill out the seal or if they did not make any allowances for the thick insulation used in large wires? Either way it's sloppy.
                Click image for larger version Name:	IMG_20170401_210955.jpg Views:	1 Size:	182.9 KB ID:	31937
                Click image for larger version Name:	wont fit insulation.jpg Views:	1 Size:	157.0 KB ID:	31938
                Had better results with the regular type posi-lock, which they have a 10-12awg for. This is important since many xt90 pigtails are 10awg, bbshd controller power wires are 12awg.

                As seen below the 10awg wire can enter the connector enough so there is no exposed bare wire at the edge of connector. So the non-waterproof connectors appear to be substantially more safe for noob use compared to the waterproof kind, if the waterproof kind were left unmodified and they just followed the directions on the package.
                Click image for larger version Name:	IMG_20170401_211627.jpg Views:	1 Size:	153.4 KB ID:	31939
                Click image for larger version Name:	xt90 10awg motor 12awg.jpg Views:	1 Size:	1.43 MB ID:	31940
                But these regular version connectors are not even slightly weather resistant, which would be very problematic for long term ebike use. Fine, we'll use some liquid electrical tape and dielectric grease.
                Click image for larger version Name:	IMG_20170401_230249.jpg Views:	1 Size:	152.8 KB ID:	31941


                yay for permatex
                Click image for larger version Name:	IMG_20170401_224842.jpg Views:	1 Size:	252.9 KB ID:	31942


                greasing inside connector
                Click image for larger version Name:	IMG_20170402_212157.jpg Views:	1 Size:	181.9 KB ID:	31943


                LET waterproofing the connector
                End result not bad after modification, tested with a 50A peak controller and they didn't even get warm. And with the modifications it is definitely waterproof..But the connector is no longer reusable, it took a bunch of extra tools, was finicky and took a bunch of time. Even if you were to drill out a posi-seal gasket instead of these mods that still requires more tools than just using a lighter and a cheap heatshrink solder sleeve, and would probably be less sealed.
                TL;DR: Kind of defeats the whole point if it is neither simple, quick, easy, or cheap.
                I've mostly used Posi-Locs on headlight shells in older BMW motorcycles where someone got in with a pair of dykes and no sense of direction. I certainly don't recommend them for all purposes, but that was an exhaustive write up. SCIENCE! Cutting the wire to the correct dimension isn't all that difficult after you flub the first one or two.

                Comment


                • #26
                  Great post. Thanks for the info . I also use copper crimp rings and a dab of solder to braise it from coming undone

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