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Recharging water batteries

Discussion in 'Power Electronics' started by pidja105, Jan 24, 2016.

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  1. pidja105

    pidja105

    106
    1
    Oct 16, 2015
    Hello,
    question is in the title, i maked alt water battery and can I rechrage it with 12V charger?
     
  2. Alec_t

    Alec_t

    2,933
    799
    Jul 7, 2015
    What voltage does your 'alt water' battery (whatever that is) generate?
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,480
    2,826
    Jan 21, 2010
    Depending on what you've used for the electrodes you may be able to simply force current into the battery.

    This depends on whether the reaction can be driven backwards. depending on your electrolyte, the backwards reaction may not be the same as the forwards one. In this case your cell is effectively a primary cell (i.e. you can't re-charge it).
     
  4. pidja105

    pidja105

    106
    1
    Oct 16, 2015
    I used copper and aluminium plates and saltwater only.Can I recharge in that case?
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,480
    2,826
    Jan 21, 2010
    Off the top of my head I can't answer. I suggest that any contaminants in your water or salt (or even the salt itself) could make the charging process problematic or impossible.

    Note that ideal charging would result in the plates returning to their original condition. Even in the best cells, this never happens and results in a decreasing capacity with every charge/discharge cycle. A lot of research and experience over many years has gone into current battery designs. A battery made of two plates of dissimilar metals in some random electrolyte is likely to achieve very poor performance.
     
  6. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    Copper can be plated from an aqueous soltion but aluminium needs a very high temperature for production. Your cell looks to be not rechargable.
     
  7. Anon_LG

    Anon_LG

    453
    117
    Jun 24, 2014
    I have made one before, me, me, me!

    You have made an aluminium oxygen battery, the copper plate acts as an uncreative electrode and plays no useful part in the reaction. From experimentation and what I have read, it is possible to extract the aluminium from it's dilute oxide sludge when discharged into the water. I discharged my aluminium battery for a while, measured a voltage drop due to depletion, I the applied a reverse voltage for a few minutes and noted a voltage increase of about 0.10 volts. So, yes you can recharge these, the voltage per cell when working with pure water makes their use in most applications absurd, I obtained 0.25 to 0.5 volts, depending on battery configuration and so internal resistance, electrolyte solution etc. You will need at least 3 volts per cell to recharge, more if possible. I noted voltage increase with a lower voltage recharge however. Try the 12 volt charger!

    Remember, when passing an electric current through salt water (an H2O, NaCl solution) you will obtain hydrogen from one terminal and more importantly CHLORINE of of the other, poisonous, not good for humans, stay away. Of course, the risk is minimal, given good ventilation and low concentrations. I would have done more work on aluminium oxide electro chemistry, very ingesting, the ability to create a rechargeable, safe cell, but a lack of equipment prevented me from obtaining any more useful data.

    The confusion with cryolite is that it is not strictly necessary for electrolytic extraction of aluminium for it's oxide, it just reduces costs. The aluminium oxide is suspended in water, allowing ionic movement, hence, there is no need for the heated cryolite used on the Bayer process.

    I hope this helps,
     
  8. pidja105

    pidja105

    106
    1
    Oct 16, 2015
    Thanks.
     
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