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  • Create Large Refuelable Metal-air Battery.

    Yes, the +.25 from the carbon will add to the cell voltage, although the relatively high resistance of carbon may negate most of the benefit. Substituting nickel for the carbon will bump it up even higher, although it will increase the cost of the battery substantially.The big advantage to iron over aluminium is that the iron version is rechargeable. The efficiency isn't great unless you seal it up to capture the hydrogen the cell releases as it discharges, and even then it's not amazing, but for cheap, practically immortal batteries that don't care about overcharge/overdischarge to hook to your solar array it's pretty good, and it's less hassle than smelting iron. Aluminum-air cells are mostly useful for powering electric drones and other things where weight is important. Especiall...

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    Yes, the +.25 from the carbon will add to the cell voltage, although the relatively high resistance of carbon may negate most of the benefit. Substituting nickel for the carbon will bump it up even higher, although it will increase the cost of the battery substantially.The big advantage to iron over aluminium is that the iron version is rechargeable. The efficiency isn't great unless you seal it up to capture the hydrogen the cell releases as it discharges, and even then it's not amazing, but for cheap, practically immortal batteries that don't care about overcharge/overdischarge to hook to your solar array it's pretty good, and it's less hassle than smelting iron. Aluminum-air cells are mostly useful for powering electric drones and other things where weight is important. Especially if you can convince your soda-drinking friends to donate their empty cans.I'd expect the thing to look for if you want an efficient set of cells would be small, plastic boxes. Put a thin plate of iron on one side, and your carbon on the other and use a piece of cardboard or several pieces of paper to separate them. I built an aluminium/copper battery like that for a science project when I was in school that worked pretty well. Iron plate is pretty cheap from the junkyard if you don't mind spending some time with a hammer to straighten and flatten what you find there. Cheaper than rebar even. Only thing is it's likely to already be rusty, so you might have to charge the battery before you can use it. Polyethelene glycol is generally much cheaper if you buy it as "RV antifreeze". Comes in gallon jugs for like $2 each. I don't know if the little bit of dye will have any effect or not.

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  • Install a 6 volt alternator on your old car!

    The higher voltage became the standard because it makes the electrical devices running on the system more efficient. Amps are what requires the bigger wires, amps are also what turns into heat. 12v starter motors turn harder for their size and weight and require less cooling. 12v lights are brighter without the fixture having to be as heavy. The only reason anybody ever bothered with 6v systems was because that's what they could get out of a generator. Once diodes were invented alternators generate power much more efficiently, are cheaper to build, and require practically no maintenance. And because of their simpler construction and better efficiency they can produce much higher voltages. Before power inverters got cheap there were boxes you could hook to the externally-regulated...

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    The higher voltage became the standard because it makes the electrical devices running on the system more efficient. Amps are what requires the bigger wires, amps are also what turns into heat. 12v starter motors turn harder for their size and weight and require less cooling. 12v lights are brighter without the fixture having to be as heavy. The only reason anybody ever bothered with 6v systems was because that's what they could get out of a generator. Once diodes were invented alternators generate power much more efficiently, are cheaper to build, and require practically no maintenance. And because of their simpler construction and better efficiency they can produce much higher voltages. Before power inverters got cheap there were boxes you could hook to the externally-regulated alternator on your vehicle to kick it up to 120v so you could run your appliances off of it. 12v is a good tradeoff for a car electrical system between cranking and lighting power and the number of cells you have to stuff into the battery compartment.

    Get an externally-regulated alternator to skip the step of having to take it apart and bypass the internal regulator. Then either build or buy a regulator for 6v. They cost about $100.These days you can also get an internally regulated 6v alternator in positive or negative ground.

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