Can You Power a Phone With a Capacitor?
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Re: Can You Power a Phone With a Capacitor?
#2This in reference to the recent stream of posts about charging a phone in 20 seconds. Or 30 seconds. Or something.
Here's the most recent, with a collection of links to others: https://news.ycombinator.com/item?id=5798189
Re: Can You Power a Phone With a Capacitor?
#3Amidst the general decline in quality of publications on the Web, it's great to see Wired, which put out lots of fluffy, inaccurate stuff in the past, publishing so many solid, interesting articles. This was fun to read, had actual equations and graphs, and made sense. I remember reading the headline about charging a phone in 20 seconds and not bothering to look at the details, because, no way.
Re: Can You Power a Phone With a Capacitor?
#4how about a flux capacitor? 1.21 gigawatts!
Re: Can You Power a Phone With a Capacitor?
#5how about a flux capacitor? 1.21 gigawatts!
I used to TA undergraduate science courses. I successfully convinced at least one generation of young minds that the SI prefix G is pronounced hard, except for power, where it is pronounced soft like J. I blamed the French for this historical oddity. They bought it.
Re: Can You Power a Phone With a Capacitor?
#6There most certainly are capacitors available that meet his specs without being unreasonably large. For example this one has a capacitance of 1200F and is only 8 cm long:
http://www.mouser.com/ProductDetail/Ioxus/RSC2R7128LR/?qs=cf...
Modeling it as a parallel plate capacitor with a mica dielectric is basically totally ignoring the part about it being a supercapacitor. He may as well have been seeing if it would be feasible to get to the moon using a wood fired rocket.
Re: Can You Power a Phone With a Capacitor?
#7how about a flux capacitor? 1.21 gigawatts!
With the right voltages, you can get 1.21 gigawatts out of a capacitor no problem! Just not for very long ;-)
Re: Can You Power a Phone With a Capacitor?
#8This guy doesn’t seem to know much about really existing supercapacitors. Assuming that 1200F is enough, you can get a 1200F supercap (Maxwell BCAP1200 P270 K04) rated for 2.7V that’s 60.7 mm in diameter and 74.30 mm tall. He’s assuming 6V, so let’s say you need two of them. That’s still way too large for a phone, but nowhere near as huge as he suggests.
Re: Can You Power a Phone With a Capacitor?
#9There most certainly are capacitors available that meet his specs without being unreasonably large. For example this one has a capacitance of 1200F and is only 8 cm long: http://www.mouser.com/ProductDetail/Ioxus/RSC2R7128LR/?qs=cf... Modeling it as a parallel plate capacitor with a mica dielectric is basically totally ignoring the part about it being a supercapacitor. He may as well have been seeing if it would be f…
Most supercaps are rated for very low voltages (this one is only rated for 2.4V), as dictated by the breakdown voltages of the dielectric and its manufacturing tolerances. A 6V-rated 1200F supercap made from the same materials will be considerably larger. Further, most electrical engineers will enforce a factor of safety beyond the manufacturing tolerances . This is doubly true for capacitors, since dielectric failure on high energy caps can be somewhat catastrophic (read: explosive).
Re: Can You Power a Phone With a Capacitor?
#10how about a flux capacitor? 1.21 gigawatts!
I used to TA undergraduate science courses. I successfully convinced at least one generation of young minds that the SI prefix G is pronounced hard, except for power, where it is pronounced soft like J. I blamed the French for this historical oddity. They bought it.
Giga actually has an acceptable pronunciation with a soft g. The American National Bureau of Standards actually has this pronunciation formalized.