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  1. #1
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    Looking for a 1.5mm2 cable with round plug

    Hi, I'm using a Magicshine MS-628C together with a Kaidomain 8-cell battery. Tons of light but shit battery time, this is most likely due to the light cutting of the power long before the battery is empty, this only gets worse because I have to use an extension cable.

    With the high current(4.12 A) and a thin cable (0.75mm2) the voltage drops alot (~0.8 V) because of the resistance in the cable. I want to solder a longer cable to the battery and get rid of the extension cable.

    Only problem is I haven't been able to find a thick enough cable with the round style plugs used on Magicshine lights and several others lights. Ideally I'd like something that's atleast 1.5mm2, or about AWG 14-15. Anybody knows of a source?
    Last edited by Endless Trails; 02-21-2017 at 10:37 AM.
    Endless Trails Outdoor Equipment - Waterproof bikepacking bags and outdoor equipment

  2. #2
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    Never seen thicker cable than 20AWG. This has 33 mOhms resistance per meter so the whole extension cable has resistance of 66 mOhms (both strands). The rest of resistance is in the connectors.

    Basic voltage drop calculation:
    Vdrop (V) = Iwire (A) Rwire(Ω) = 4A x 66mOhms = 264mV or 0.264V

    Based on that I would say the connectors are real problem here.

    Getting rid of one connector would already improve the situation. Using a proper lenght would be next step. Now you are getting close to 2 meters with 1m extension, 0.6m at battery side and some length at light. I'm shure you don't need it that long.

    BTW, what AWG is cable on the light side?

  3. #3
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    Hi ledoman, I missed your reply.
    The light cable is 50 cm and the battery cable is 55 cm. I only have 1 meter extension cable so just over 4 meters in total when you count both ways. This is too long for me, I only need 1,4 meters to go from the battery in my pocket to the headlight but since I only have a 1 meter extension cable it'll have to do.

    Battery cable is marked 20awg, light and extension cable is unmarked but I cut open another extension cable and it was approximately 0.75mm2 or AWG20 (I just realised I missed a 7 in 0.75mm2 in my initial post).

    So far I haven't been able to source another cable that's thicker than 20awg with the round connectors molded to the cable. It would be nice to preserve connectability between all of my lights and batteries but i'm seriously considering cutting the light cable really short and use some other waterresistant connectors with thicker cables.
    Endless Trails Outdoor Equipment - Waterproof bikepacking bags and outdoor equipment

  4. #4
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    I would encourage you to try with different connectors. I agree it is nice to have connectability between all ligts, that's why almost no one has done it. I would realy like to see how much we are loosing in those standard 5.5x2.1mm connectors. Since this is quite important to you it would be nice to measure looses before and after change at different currents. It is easy to calculate resistance of standard wires, but it is harder to measure it over the connectors, since tipical DMMs are not very precise at those low values. Mine have min of 0.1 Ohm.

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