Are you really saying that a metal bucket full of saltpeter (tree stump remover) is “exotic” compared to a giant electrical battery based on lithium, a metal which doesn’t exist in nature, violently explodes on contact with water, and needs a solid-state electronic charge controller to keep the battery from exploding when you charge it? Why would you say something like that?
By itself it's not exotic. Using it in molten state to cook things is exotic, yes.
Lithium clearly exists in nature. Elemental lithium might not, but they don't make the batteries from that either.
Molten salt also explodes on contact with water.
A charge controller is unnecessary. It's just a cheap way to improve efficiency. The bucket of salt would have a similar controller.
Also since price isn't a part of the equation for whether it's exotic, feel free to mentally replace the lithium ion battery with a lead acid one, made out of utterly boring materials and full of water.
You have some good points. I didn't realize that lithium-ion batteries didn't actually contain metallic lithium! I thought they did, just like nonrechargeable lithium batteries, but you're right. Thank you!
However, I don't think it's true that the charge controller is just a cheap way to improve efficiency; it's actually necessary to keep the battery from exploding like a firebomb when you try to charge it.
The bucket of molten salt has a much higher energy density for cooking purposes, although you're right that this only becomes an overwhelming factor if you consider joules per dollar instead of joules per kilogram. Lead-acid batteries are 0.17 MJ/kg; the particular molten saltpeter mix commonly used for energy storage is 0.16 MJ/kg just from the melting, plus another 0.3 or 0.4 MJ/kg from melting, depending on the temperature range. The practicality difference is that saltpeter costs US$1/kg, while lead-acid batteries cost about US$6/kg.
>However, I don't think it's true that the charge controller is just a cheap way to improve efficiency; it's actually necessary to keep the battery from exploding like a firebomb when you try to charge it.
You only need to worry about it when you're riding near the edge of what the batteries can handle. If your solar array outputs 4 volts and needs a minimum of 6 hours to mostly-charge the batteries, and your batteries are in a nice cool basement, I'm pretty sure you can just hook them all together. It wouldn't be ideal but I don't think you'd have any real fire hazard.
