1. Where do I find the ESR on the spec sheets - is that "Internal Resistance"? I was reading Maxwell's UltraCap FAQ and they claim to have a much lower ESR than other super or ultra caps, but I'm not sure were that is specified on their spec sheets... Here is their FAQ: http://www.maxwell.com/support/faqs/type.asp?iType=15 Here is their 10f small ultracap: http://www.maxwell.com/ultracapacitors/products/PC10.html

Posted at 3:08PM on Sep 3rd 2006 by Gray cube

2. Well at least projects like this can serve as learning project for those who are just learning electronics. Lets see more of the same in the future to make learning exiciting.

Posted at 3:08PM on Sep 3rd 2006 by LUKE

3. to m56: Super caps are not much use (yet) for audiophiles (except for backing up your presets) as they have a very large Equivalent Series Resistance (ESR). The aluminum-electrolytic caps (those monsters used for car audio) have an ESR of ~.01 to .0001 ohms which allows them to dump their energy quickly to boost the current available form the battery to make those huge bass notes possible. a super cap on the other hand has an esr many times higher than that; this cap can only provide 9a, almost nothing compared to the thousands possible with electrolytic caps. btw, elliot can we got rid of the Weblogs, Inc. Customer Service from the post activation e-mails?

Posted at 3:08PM on Sep 3rd 2006 by ...

4. Correct me if i'm wrong, but in beam, it merely uses the circuit for voltage detection and amplification to send the power to the motor. Basically, the solarcell charges the cap directly, and the rest of the circuitry is the trigger.

Posted at 3:08PM on Sep 3rd 2006 by kmangwing

5. (not the same hans as in #44) afroman post #40: "he states the quiescent draw of the converter is 2ma at 2.3v, meaning a 4.6mw draw with no load, or 0.0046 joules per second." Your mistake is that you take this number as a constant in the next calculation. As the voltage of the supercap decreases, so will the current (most probably), so the power (=U*I) will decrease even faster. With this underestimation you get 1.6 hours, so I think that if you take the diminishing power draw into account, 3h seems very plausible.

Posted at 3:08PM on Sep 3rd 2006 by Hans

6. #26 and #27, I thought the same thing. 1 farad car audio caps are the size of soda cans or spraypaint cans... I did some googling and these supercapacitors are apparently different kind of thing, with different pluses/minuses. wiki: http://en.wikipedia.org/wiki/Supercapacitor http://en.wikipedia.org/wiki/Capacitor Also here's some company page that mentions both: http://www.cap-xx.com/resources/reviews/strge_cmprsn.htm Unfortunately I couldn't glean whether these supercapacitors make regular caps obsolete, or if they are just used for different things. I'm sure car audio buffs would prefer to use a tiny $5 unit that has ten times the storage as their $100 1farad caps if it were directly applicable... can anyone explain the difference?

Posted at 3:08PM on Sep 3rd 2006 by M56

7. Ugh, I just spent 15 minutes trying over an over to post a comment, is there a size limit that it is not telling me? It kept telling me rejecting my comment field.

Posted at 3:08PM on Sep 3rd 2006 by Hans

8. Pocketbrain: Thanks! the compartiment is 3AAA cels sized. i wonder if 2 capacitors of lower size in series would have the same efect. I also wonder if it could take, let's say, 4 ours of photos. normal bateries drain in 7days if not used to feed the internal memory, wich i dont use.

Posted at 3:08PM on Sep 3rd 2006 by rui maldonado

9. oh gosh... i need autoupdate for firefox... again... well, as far as i have seen, it is almost useless unless used for emergency power for a mobile phone, for example. but really, has anyone experienced yet the autonomy of these cells? I would love to experiment, even in a flash light.

Posted at 3:08PM on Sep 3rd 2006 by rui maldonado

10. "I Think that this is a wonderful thing, I mean you could have a flashlight that needed to charge for like no time, and could run for a couple hours" You guys are greatly overestimating the power of these caps. A 10f 2.3v super cap stores about 25 joules; it could raise 1g of water by ~50F. That is also about the amount of energy used in the flash of a disposable camera. That 10f cap would power only a single LED for a few minutes, almost useless for a flashlight.

Posted at 3:08PM on Sep 3rd 2006 by ...

11. He says it will run a light load for 3 hours without a recharge... but that's a pretty big exaggeration. He states the quiescent draw of the converter is 2ma at 2.3V, meaning a 4.6mW draw with no load, or 0.0046 joules per second. Energy stored in a capacitor = 0.5*C*Vsquared So stored energy = 0.5*10Farads*2.3*2.3 = 26.45 Joules. 26.45 / 0.0046 = 5750 seconds of runtime assuming that the 100% of the capacitor's energy is used (not likely). Meaning that after about 1.6 hours of this circuit powering absolutely NOTHING, the cap will have fully discharged. It's a cute hack, but he should have used a proper low power dc-dc converter circuit.

Posted at 3:08PM on Sep 3rd 2006 by Afroman

12. My number for AAA could be wrong so lets use 900mA instead of 2800mA. Point is thats 4 minutes of mp3 player time. The difference between a conventional battery and this 10F supercapacitor is on the order of 1000 times the capacity. Lets say I wasn't half off but was 10 times off, that still is 100 times less capacity. I have supercapacitors here. For microcontrollers, leds, and pager motors they are great. According to this school physics site, a 10F supercapacitor will do over 30 seconds with a standard flashlight bulb. A couple hours is 7200 seconds by my calculation. Off by 240 times. http://www.djb.co.uk/SidePages/PhysicsPages/electricity.html (bottom of page)

Posted at 3:08PM on Sep 3rd 2006 by Mike

13. "I wonder fi the gauss pistol could benefit from these gold-cap capacitators...." Actually, not really because the discharge time is in the seconds according to the article. Now if they made these with a much lower ESR...

Posted at 3:08PM on Sep 3rd 2006 by bakagamer

14. I Think that this is a wonderful thing, I mean you could have a flashlight that needed to charge for like no time, and could run for a couple hours Mike, I think your numbers for the amount of power from a AAA are off by a factor of 2. According to Energizer, the bottom level Energizer AAA is only 1250 mah. That is roughly one half, but my point being, these capacitors hold a lot more juice than youd think....

Posted at 3:08PM on Sep 3rd 2006 by Jethro

15. Yay, my second mainpage post! (The other was the georgia tech student's robotic guitar)

Posted at 3:08PM on Sep 3rd 2006 by nullset

16. Unless your waste basket is the size of an AA battery, then yes... I'm staring at a 1 farad 5.5v super cap from allelectronics.com .78" in diameter and .30" thick. Not too huge at all.

Posted at 3:08PM on Sep 3rd 2006 by Pedro

17. Guys, this 10F supercapacitor would run a mp3 player like my little muvo tx for less then 2 minutes on a single charge. AAA battery of 1.5V and 2800mAh = 4.2 Wh. A 10F supercap at 2.5V would be 0.00694 Wh. My Muvo runs for 14 hours on the AAA battery. 14 hours * 0.00694 Wh /4.2 Wh = 0.02315 hours or 1.4 minutes. Even a $25 50F supercap which is one of the most powerful ones would only give you 7 minutes of listening time. A camera would eat one of these up just as quick. Supercaps are great for beam, solar, leds etc but are a factors off to replace batteries in most applications. Supercaps are great for instant power (so fast charging/discharging) but not great for energy storage. The reason these supercaps are so small and light is that they use aerogel for the large amount of surface area. http://www.eepn.com/Locator/Products/ArticleID/28446/28446.html

Posted at 3:08PM on Sep 3rd 2006 by Mike

18. http://www.mutr.co.uk/prodDetail.aspx?prodID=337 i guess it could be 10f then

Posted at 3:08PM on Sep 3rd 2006 by captsnuffy

19. Yay for BEAM. It's been a while since I've followed anything in the BEAM area, anything interesting happen since, oh say... '99? Just to re-inforce others, that is definitely 10 farads, as stated in the article, I don't think a 10 microfarad capacitor would even drive a single cycle of the oscillator (seeing as the other two caps are 100 uF each). I'm more excited about puting this idea into devices, than using it to replace batteries, personally. If you need to keep an MP3 player going for the 30 minute commute to school/work, and you forgot to charge it the night before, it's much easier to let it charge for under a minute when you're rushing to get out the door. Oh the possibilities.

Posted at 3:08PM on Sep 3rd 2006 by -Pat

20. this would be good for smokedetectors. cuz they are run on house circuts but the 9v is there for when power lines fail

Posted at 3:08PM on Sep 3rd 2006 by phycon