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Can You Power a Phone With a Capacitor?

wired.com

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Re: Can You Power a Phone With a Capacitor?

#51

Post by benjamincburns »

venomsnake wrote: post #38
benjamincburns wrote: post #9

Earlier quoted context omitted.

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 failur…

Why would you need 6v for a phone? I got feeling this was pulled out of his ass. Everything works on sub 2V there if I am not gravely wrong (not sure for the light source for the display)

You don't. I'd bet most of the voltage rails on a modern phone are 1.8V and 3.3V. Then the display backlight usually uses a constant-current regulator, and you'll probably have some oddball low voltages for the CPU core and other various things. Given Ohm's law you can generate all that using DC-to-DC converters.

Re: Can You Power a Phone With a Capacitor?

#52

Post by benjamincburns »

leephillips wrote: post #34
aidenn0 wrote: post #31

Earlier quoted context omitted.

Is my sarcasm detector broken? This is a fluffy inaccurate post masked by a bunch of equations any apt high school physics student could have gotten from their textbook. Nobody uses mica capacitors for high energy-density applications, electrochemical EDLC's have much higher energy densities. Furthermore switching regulators that can operate the phone relatively independent of input voltage are cheap and efficient. Y…

I was not being sarcastic, so don't worry about your detector. This was the way a physicist would take a first look at the problem, so I could relate and I enjoyed it. You and some other critics here are taking the author to task for not writing a detailed electrical engineering analysis, but I don't think that's entirely fair. Although the article is not completely accurate in that sense, it's also not "fluffy", and…

> You and some other critics here...

You're probably referring to me, since I've been posting all over this thread and I did nothing to preface my criticisms. I really didn't mean to "take the author to task," and I was as astonished and happy as you were to see this piece in Wired. This was just something I became interested in when the news first hit, and for whatever reason I've enjoyed talking about it and breaking it down more than usual.

The only thing I'd criticize him for was that he's basing his back-of-the-envelope on some arbitrary things (the 6V rating and choice of a ceramic/mica dielectric, for instance) rather than trying to base it on an appropriate lower bound. Had he done the latter he would've reached the same conclusion but with a far less outlandish example. It's only bad because relatively small supercaps which would have worked for his example do exist (much to the chagrin of the news stories he's criticizing), and his example makes it look like he's suggesting otherwise.

Re: Can You Power a Phone With a Capacitor?

#53

Post by leephillips »

benjamincburns wrote: post #52
leephillips wrote: post #34

Earlier quoted context omitted.

I was not being sarcastic, so don't worry about your detector. This was the way a physicist would take a first look at the problem, so I could relate and I enjoyed it. You and some other critics here are taking the author to task for not writing a detailed electrical engineering analysis, but I don't think that's entirely fair. Although the article is not completely accurate in that sense, it's also not "fluffy", and…

> You and some other critics here... You're probably referring to me, since I've been posting all over this thread and I did nothing to preface my criticisms. I really didn't mean to "take the author to task," and I was as astonished and happy as you were to see this piece in Wired . This was just something I became interested in when the news first hit, and for whatever reason I've enjoyed talking about it and break…

"You're probably referring to me"

No, your comments were informative while politely avoiding direct criticism of the author. And you make another good point here.

Re: Can You Power a Phone With a Capacitor?

#54

Post by jtoeman »

geuis wrote: post #27
finnh wrote: post #13

Earlier quoted context omitted.

gigga what? gigga who? Switcha flow, getcha dough EDIT: apparently downvoters don't like Jay-Z.

You're being downvoted because your comment is inane, off topic, and adds nothing of value to the conversation. Even the grandparent quotation from Back to the Future suffers from the same problem and is being downvoted.

message clear - hacker news: NOT the place for idle joking
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