Comment on YSK: You can make supercapacitors out of cement, water and carbon black
homesweethomeMrL@lemmy.world 5 days ago
It is cool, and yes the prototype they made is the size of a coin battery. They made three 1v “super capacitors” and linked them together to light a 3v LED.
That said, my only question was should they ever get it to be able to store and discharge 10kW, wouldn’t it necessarily all discharge at once? Like, it’s not a battery - but that’s a small problem after they’ve solved the big ones.
SoleInvictus@lemmy.blahaj.zone 5 days ago
Failed electrical engineering major here - it turned out I was built to be a scientist, not an engineer, but it took a year of EE classes to figure that out.
Regarding energy storage, capacitors aren’t much different than batteries, but they can charge/discharge faster, have lower energy density (units of stored energy per units mass), and self-discharge faster, hence why they aren’t used in place of batteries. For something where weight and volume aren’t an issue and with no need for long-term storage, like a solar-equipped house, a huge cap would be a great option. I’m trying to figure out how to build one of what’s described it the article now.
The rate at which a capacitor discharges varies just like a battery, proportional to the resistance of the circuit. The reason most folks associate capacitors with “shorted terminals go boom” is the maximum rate of discharge on a capacitor is much higher than a battery, plus some capacitors operate at a much higher voltage than is practical for a battery, increasing the likelihood of generating a small arc. Shorting the terminals with a conductor makes a low resistance circuit so it just dumps its charge, whereas a battery would max out at a much lower rate, typically making a toasty wire versus a vaporized or melted wire.
homesweethomeMrL@lemmy.world 5 days ago
Thank you!