http://defensetech.org/2007/07/05/attack-of-the-battery-man/ The Future of the Military, Law Enforcement and National Security Fri, 10 Feb 2012 07:19:56 +0000 hourly 1 http://wordpress.org/?v=3.3.1 http://defensetech.org/2007/07/05/attack-of-the-battery-man/#comment-62848 Swiftek Thu, 14 Aug 2008 21:34:38 +0000 http://deftech.usmilblog.com/?p=3601#comment-62848 Someone here should pull the obvious spam comments to maintain the integrity of this site (if there is any.) Someone here should pull the obvious spam comments to maintain the integrity of this site (if there is any.)

]]> http://defensetech.org/2007/07/05/attack-of-the-battery-man/#comment-163693 Torkel Fri, 06 Jul 2007 15:21:49 +0000 http://deftech.usmilblog.com/?p=3601#comment-163693 I made some quick and rough calculations. First the requirements: 20 W continuosly for 96 hours, with an intermittent peak power draw of 200 W. That is 2 kWh and the total weight of the system needs to be under 4 kg. Lithium ion batteries top out at 160 Wh/kg, so you need chemical energy for this to work (gasoline is ~10 kWh/kg). The peak power draw probably means you want a chemical power/battery power combo, as a chemical system is optimized for a specific power level. What chemical energy to use? I see two approaches: One is to go buy a state-of-the-art fuel cell at about 25 W, a hydrogen container and a battery. Combine these with some electronics and you should make the specs. Problem here is that fuel cells are tricky to work with, and hydrogen is even worse. I'm not sure I would want to carry a hydrogen tube on a battlefield.. The second option is to buy a small liquid-fuel engine, such as an R/C engine, an electric motor acting as both generator and starting motor, a battery and a fuel tank. I looked at R/C engines and the smallest one I found was called "OS MAX-10LA" with a deplacement of only 1.6 cc, weighing 110 g. That tiny engine still produces 0.2 kW, so it only needs to operate for 15 minutes every other hour or so. The main problem with this is the noise level of the engine: although ~80 dB is low for an R/C engine, it is quite loud if there is somebody close you'd rather not be heard by. A possible third approach might be a direct methanol or other liquid fuel cell. But I have not seen these available for purchase, so unless you are working for some large Japanese electronics manufacturer this is probably a non-option. (And if you are: sorry, competition is US-nationals only.) If I was in college, I'd gather a team, buy an R/C engine and see how much electricity it can produce and what fuel-consumption it has. The parts are only ~$200 total for that approach. I made some quick and rough calculations. First the requirements: 20 W continuosly for 96 hours, with an intermittent peak power draw of 200 W. That is 2 kWh and the total weight of the system needs to be under 4 kg.
Lithium ion batteries top out at 160 Wh/kg, so you need chemical energy for this to work (gasoline is ~10 kWh/kg). The peak power draw probably means you want a chemical power/battery power combo, as a chemical system is optimized for a specific power level.
What chemical energy to use? I see two approaches:
One is to go buy a state-of-the-art fuel cell at about 25 W, a hydrogen container and a battery. Combine these with some electronics and you should make the specs. Problem here is that fuel cells are tricky to work with, and hydrogen is even worse. I’m not sure I would want to carry a hydrogen tube on a battlefield..
The second option is to buy a small liquid-fuel engine, such as an R/C engine, an electric motor acting as both generator and starting motor, a battery and a fuel tank. I looked at R/C engines and the smallest one I found was called “OS MAX-10LA” with a deplacement of only 1.6 cc, weighing 110 g. That tiny engine still produces 0.2 kW, so it only needs to operate for 15 minutes every other hour or so. The main problem with this is the noise level of the engine: although ~80 dB is low for an R/C engine, it is quite loud if there is somebody close you’d rather not be heard by.
A possible third approach might be a direct methanol or other liquid fuel cell. But I have not seen these available for purchase, so unless you are working for some large Japanese electronics manufacturer this is probably a non-option. (And if you are: sorry, competition is US-nationals only.)
If I was in college, I’d gather a team, buy an R/C engine and see how much electricity it can produce and what fuel-consumption it has. The parts are only ~$200 total for that approach.

]]> http://defensetech.org/2007/07/05/attack-of-the-battery-man/#comment-62844 Hoax Meister Fri, 06 Jul 2007 13:55:00 +0000 http://deftech.usmilblog.com/?p=3601#comment-62844 I'm guessing that Larry Rome's power-generating backpack will contend for this prize. Much easier to create the power (and store it) thru movement than to just carry the power around. http://www.newscientist.com/article.ns?id=dn7970 I’m guessing that Larry Rome’s power-generating backpack will contend for this prize. Much easier to create the power (and store it) thru movement than to just carry the power around.
http://www.newscientist.com/article.ns?id=dn7970

]]> http://defensetech.org/2007/07/05/attack-of-the-battery-man/#comment-62843 Battery Fri, 06 Jul 2007 02:01:57 +0000 http://deftech.usmilblog.com/?p=3601#comment-62843 I guess you can join global battery directory at http://www.global-battery-directory.com to gain more information. I guess you can join global battery directory at http://www.global-battery-directory.com to gain more information.

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