1. andre 2
    Flame

    Battery hacks

    Hi all.

    Has anyone here tried to DIY their own rechargeable batteries?

    This covers:- buying "dead" packs on Ebay and reviving them, as well as scratch building cells.

    I've heard that making lead acids is feasible but my latest research is into perfecting the calcium ion cell.

    The plan here is to use calcium carbide, a known high energy compound familiar to cavers for lighting and convert it into a two stage electrochemical storage medium using intercalated graphite and iron phosphate.

    The cell would consist of a CaC/C mix as the anode and FePO4 as the cathode which would then form the ion shuttle as in LiFePO4 technology.

    It occurs to me that an electrolyte consisting of acetone and a few stabilisers would hold the acetylene stable until the cell is discharged; in its fully discharged state it would be essentially inert.

    As the entire cell is anhydrous the reaction should be fully reversible and long term stable.

    Acetone also happens to be relatively inexpensive though somewhat flammable but no more so than any other electrolyte commonly in use.

    It has some useful properties such as dissolving acetylene so the cell would need to be minimally pressurised and in fact be ideal for high drain applications if failsafes are used.

    1. andre 2
      Boffin

      Re: Battery hacks

      Interestingly, this page http://ma.ecsdl.org/content/MA2012-02/8/664.full.pdf details just such a beast.

      They are using liquid metal ie indium/calcium alloy electrodes to get around many of the passivation problems, so if the price of indium were to drop or another metal were substituted for indium such as sodium (liquid at high temperature) it should still work.

      For certain uses a battery whose electrodes freeze at 5 Celsius wouldn't be a big problem, such as e-bikes where a few minutes use will warm them up nicely.

      Worth a look, as copper PCB feedstock could be used as the base plates.

      Also viable is to plate a transition layer onto a sheet of glass ie ITO, then vacuum deposit silver or copper over that so all those otherwise useless sheets of glass from broken flat screens could be recycled.

      Also worth mentioning is that controllers have moved on a lot since 2012, the advent of single chip 16 pin FPGAs means very complex algorithms can be used to overcome nonlinearity with temperature and charge state and pressure feedback via BMP085 etc.

  2. ZoraJEdwards

    Hey! I also want information about DIY battery hacks

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