I’m wondering if there is a decent affordable cell welder. Purpose is rebuilding tool batteries and that sort of thing on an occasional basis. K-weld has been recommended but is pretty expensive and might be overkill. https://diy500amp.com/ has a bunch closer to my price range but might be underkill. Any thoughts? Thx

  • solrize@lemmy.mlOPEnglish
    2·
    21 days ago

    Thanks! There is a Torque Test channel video where they tested Milwaukee and Ryobi jump starters and found they delivered around 4WH and 3WH of energy respectively. They use a tool battery to charge a capacitor, then use the capacitor to jump start the motor. I thought I had seen a teardown of the Ryobi once, that showed the capacitance, but I don’t seem to have saved a link. But let’s see, E= 4WH = 14.4kJ = 1/2CV^2 where let’s say V is initially 14.14 volts so 1/2 C V^2 = 1/2 C 200 = 100C = 14400J. So C = 144 farads, can that be right? They are supercapacitors after all, and the jump starter is a fairly large box of them.

    Here’s the jump starter test vid: https://www.youtube.com/watch?v=z4N5txe7oZA

    This claims to be a 100 farad 13.5V capacitor bank (5x 500 farad 2.7V in series): https://www.aliexpress.us/item/3256804444528644.html

    The jump starters are a fair amount bigger than that bank.