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Every kid who has been to a science fair knows that you can make a battery with a lemon, a potato, a penny and a nail. I've never done this and I'm not entirely clear on how it works beyond a hazy recollection of undergraduate-level chemistry class; but I gather that you do not need to use a lemon and potato as your power source but can in fact use any number of substances willing to donate or accept electrons.

My question is this: are there any home-made batteries that can produce sufficient electrical energy that its cheaper to make them yourself rather than plug your appliance into the wall or use store-bought batteries

I realize that there are a number of variables here that might make a significant difference in whether its cheaper to use established electricity sources or create your own so for arguments sake lets say that I am trying to: - charge a cell phone/laptop - run a microwave long enough to make popcorn - keep a refrigerator cold

Lets also consider the dual possibilities that I: - live in a city apartment and have to buy all my fuels and materials - live on my own far where I can grow as much produce as I want to devote to making batteries

If there are other good fuel sources that could be a logistic variable; let me know in the comments so I can edit the question accordingly.

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    $\begingroup$ It should be pointed out that the lemon/potato does not function as a power source in such batteries. Instead, it functions as the electrolyte of the battery. The power is instead coming from the oxidation/reduction of the metal in the electrodes. (Copper & zinc in the most common configuration.) $\endgroup$ – R.M. Jul 13 '15 at 21:21
  • $\begingroup$ @R.M. Well, oxidation anyways. It's just hydrogen evolution at the copper electrode, not a reaction of the electrode itself. I suppose one could make ethanol out of the potatoes or whatever for use in a fuel cell/generator, but certainly not the most efficient thing. $\endgroup$ – Michael DM Dryden Jul 13 '15 at 22:19
  • $\begingroup$ The second possibility assume you "grow" your electrodes, too, i.e. you have a functioning mine and smelting facility... In other words, it is rather unrealistic. Also, you forgot to discuss environmental issues. Producing energy via batteries will leave you a lot of dead batteries, i.e. most likely toxic metal salts. If you go the DIY way, you should figure out a DIY disposal, too. $\endgroup$ – Greg Jul 14 '15 at 6:02
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No: trying to catch up with 100+ years of technological optimizations in your kitchen won't be an economical enterprise. Store-brought batteries are standardized and relatively inexpensive. Power from an outlet is even less expensive (by one or two orders of magnitude).

On the other hand, in many places you can save on electricity by going solar. Even if you can't install solar panels on your roof because you don't own a house, you could buy solar chargers for small appliances if you have a sunny corner in your apartment...

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In general, think of batteries (including chemical nonrechargeable ones) as tools for storing and transporting energy, not as an energy source.

If you want to create energy through chemistry, then the economically efficient way is the way everyone else does it, through exothermic oxidation - burn stuff and use it to power a generator.

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A Nickle Iron or iron copper battery,is most practical. A pint jar sized one is similar to a AA in voltage and similar to a lead acid battery in usable current, it's also easy enough to seal since it already has a lid. The self discharge rate is pretty high so you would have to keep your batteries empty or on a trickle charge to keep them usable. The major advantage is the long lifespan (rechargeable for nearly 70 years), and the electrolyte which is common lye. If the battery dies or spills you can neutralize the lye with vinegar,clean the plates with water and then refill it with lye and water. This will fully recharge the battery instantly and restore your battery's ability to hold a charge. I know there are countless articles online about the dangers of lye but people have been using it for 100's of years to make soap,and it's not particularly harmful to the environment. You still want gloves goggles and vinegar on hand, it eats skin similar to the way household bleach does. (bleach has lye in it)

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  • $\begingroup$ Bleach doesn't have lye in it, though you can make it by adding elemental chlorine to lye (just as you can make NaCl by adding HCl to lye.) What makes bleach corrosive is the resulting oxidiziing ion (hypochlorite). $\endgroup$ – Silvio Levy Jul 14 '15 at 11:26

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