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Battery Chemistry

Discussion in 'Power Electronics' started by cjdelphi, Nov 19, 2016.

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  1. cjdelphi

    cjdelphi

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    Oct 26, 2011
    Indide a dry battery / heavy duty battery, we have the shell casing to act as the negative, and the "rod" inside is the positive...

    Excuse my ignorance but... a carbon rod, is that not the same as a ferrite rod? I can pull out of an old radio?

    I've been making batteries tried copper/zinc/other metal combos, best i got was a battery consisiting of drain cleaner for the electrolyte, a little copper sulphate and then a series of copper and zinc plates, it recharged! 3amps at peak

    But the capacity was low 0.8v but had high current draw and the worst that would happen is boiling the electrolyte...

    So today i'm pulling "rods" out of heavy duty batteries, discarding the case and replacing it with aluminium

    Anyway... ferrite rod the same as a carbon rod? Thanks
     
  2. davenn

    davenn Moderator

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    Sep 5, 2009
    carbon is carbon
    ferrite is iron
     
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  3. duke37

    duke37

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    Ferrite is an iron based compound (spinel?) but can also contain other elements to optimise the magnetic properties. It is made with a very high resistance to reduce the Eddy currents in an alternating magnetic field.
    You will not be able to use it as a battery electrode.
     
  4. cjdelphi

    cjdelphi

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    Oct 26, 2011
    I see, thanks!
     
  5. Anon_LG

    Anon_LG

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    The "rods" I have found inside zinc batteries have sometimes been the zinc, sometimes the carbon. In the smaller varieties the rod looks more like a nail and is usually the zinc, whereas in the larger ones the rods are graphite and are black.

    The carbon acts as the neutral cathode, it is effectively the only material that is readily available for this purpose, graphite is sometimes used, other times it is compacted carbon black (a carcinogen, don't breath in). Glassy carbon is another option as is graphene, but you won't find these in zinc batteries. You can use copper, it's reduction potential is low, therefore it's action overall short amount of time is discountable, but it will slowly react with acids.

    Iron on the other hand is reactive and will react in aqueous solution, forming hydroxides and oxides of iron. Iron presents a redox potential of 0.89 for oxidation to hydroxide https://en.m.wikipedia.org/wiki/Standard_electrode_potential_(data_page) because this value is has the like negative sign to zinc, the overall potential difference will be weakened from the standard zinc 1.2 volts down to about 0.4 volts.

    Aqueous chemistry batteries are not the best for recharging as you will always create hydrogen gas. In SLAs the gelled electrolyte allows the gas to recombine with the sulphate ions, to reform sulphuric acid, increasing lifetime, but it is not indefinite and requires water topping every so often.

    If you need graphite, burn some pencils. Decent quality ones, I find the wood in the cheap ones break the graphite sticks. But if the rods you are getting out of the premade batteries are the carbon ones, certainly use these.
     
    cjdelphi likes this.
  6. cjdelphi

    cjdelphi

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    Oct 26, 2011
    Good info cheers :)
     
  7. Audioguru

    Audioguru

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    Sep 24, 2016
    It sounds like you are making an old Carbon Zinc battery. They are not made here anymore but leaky "heavy duty" carbon zinc batteries are made in China. Ordinary disposable batteries here are alkaline type that are much better than the old carbon zinc type.
     
  8. cjdelphi

    cjdelphi

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    Oct 26, 2011
    I'm trying every combo of metals

    Zinc/copper/tin/iron along with alum powder/drain cleaner among others, but after experimenting i'm looking for something that acts like a lead acid battery, so i'm off to the hardware store for sulphuric acid ... i'm on a break so i thought i'd try something different but fun :)
     
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  9. Audioguru

    Audioguru

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    When I was young my friends and I did not make batteries, instead we made rockets and very powerful fuel for them. They all blew up! Luckily none of us were injured.
     
  10. davenn

    davenn Moderator

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    a good learning experience :)
     
    cjdelphi likes this.
  11. cjdelphi

    cjdelphi

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    Oct 26, 2011
    I can explain why i need battery acid to the anti terrorism squad maybe not so much rocket fuel lol
     
  12. spaceman

    spaceman

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    Nov 5, 2016
    Be super careful with any type of liquid acids or bleach and dry cell batteries. Some of the combinations make anhydrous halogens that are on par with anhydrous ammonia. This is as bad as it gets and no second chances.
    Don't let kids play with batteries.
     
  13. cjdelphi

    cjdelphi

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    Oct 26, 2011
    One could say the same about high voltage capacitors and non isolated high voltage circuits
     
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