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Backpack generator
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Backpack generator on 09/10/2005 15:21:32 MDT Print View

Researchers at U Penn published an article yesterday describing a backpack that takes the energy created in the act of walking to generate 7.4 watts of power. Basically, the same principle in the watches that use the bouncing movement of your wrist to eliminate the need for batteries.

I'm skeptical that this will be light enough to warrant carrying in leiu of batteries on everyday trips. But it is exciting if you think about long trips or the promise the technology brings to individual devices like a GPS.

It's also exciting in terms of bringing greater awareness and momentum for renewable energy to the general marketplace.

A public release can be found here:


paul johnson
(pj) - F

Locale: LazyBoy in my Den - miss the forest
Re: Backpack generator on 09/10/2005 18:17:16 MDT Print View

85 lbs was the weight in the Yahoo news article.

it's not clear from this article precisely what the wt of the pack alone is. their test condition used just under 85lb. not very practical except if part of an expedition or squad.

Edited by pj on 09/11/2005 11:36:50 MDT.

Ryan Jordan
(ryan) - BPL Staff - MLife

Locale: Greater Yellowstone
Re: Re: Backpack generator on 09/11/2005 00:49:20 MDT Print View

>> 85 lbs was the weight in the Yahoo news article.

That's 1300 packets of Gu - 130,000 calories, i.e., 43 days at 20 miles per day or 860 miles.

"But with my iPOD charged the whole time!"

TIC sorry, couldn't resist ;)

paul johnson
(pj) - F

Locale: LazyBoy in my Den - miss the forest
Re: Re: Re: Backpack generator on 09/11/2005 02:36:43 MDT Print View

cute. very cute. you got a good chuckle out of me.

1day on trail carrying it - my body would be Gu.

obviously, the pack is meant for the military or research expeditions with porters(?). something with radio, satcom, laptop, or a lot of camera/video equipment.

Al Clemens
(al) - F
generator bp weight.. on 09/11/2005 09:26:49 MDT Print View

Actually the pack doesn't weigh 84 lb. But, the energy claims of producing 7.4 watts were while carrying 44-84 lb loads to activate the energy generating suspension.

Moving a magnet against a coil to generate electricity is nothing new. What I found interesting is their finding that a suspension pack is more ergo efficient, reducing up/down gait of the wearer.

In this nat'l geographic article, it claims the weight of the pack "to be only slightly more than a normal pack,equivalent to carrying an extra candy bar".

Re: generator article on 09/11/2005 12:37:50 MDT Print View

Hmmm, that Nat'l Geo article had some better information than the original link I provided. All the same, it would be pretty sweet if the technology could be built into a Foretrex, or for the good doctor, an ipod nano (have you seen the new nano? now that's sweet!).


Mike Barney
(eaglemb) - F

Locale: AZ, the Great Southwest!
Pack based Generator on 09/11/2005 14:00:07 MDT Print View

I found the 'as light as a "candy bar" notation interesting. I didn't see any analysis on possible costs. The idea looks simple enough that it should be easy to productionize quickly. I believe you can get a solar panel that will cover the top of your pack yielding several watts weighing several ounces.

Mike B

Al Clemens
(al) - F
solar on 09/11/2005 21:00:08 MDT Print View

Yeah, I was thinking the same thing on the flexible solar arrays. Brunton's $169 4.5 watt model weighs 6.5 oz and is 22"x12", a bit big for the top of a pack but could be duct taped down the back.

I'm sure you could make a comparatively "UL" generator pack (ala luxury lite)designed for lighter loads to move the suspension sys and power the generator. And it would give juice rain or shine, which is nice. But the thought of going back in time to an external frame pack (even if it does have suspension) doesn't appeal to me for off trail boulder fields and bushwacking. 'Course I only carry a headlamp and once in a blue moon a cell phone, so a couple extra lithium batteries would be lighter yet!

Mike Barney
(eaglemb) - F

Locale: AZ, the Great Southwest!
solar on 09/12/2005 00:00:06 MDT Print View

I believe they indicated the 7 watts was peak, and would be suprised if you could get a sustained 7 watts out of the backpack.
If you think about a limited amount of electronics a 1/2 to 1 watt panel, on the rough size of 5" x 10" would work well. I have a 1/2 watt panel, currently used for other purposes, which would keep a cell phone (or iPod, etc) charged. I like your idea, I think I'm going to try it out.

Mike B

paul johnson
(pj) - F

Locale: LazyBoy in my Den - miss the forest
Re: solar on 09/12/2005 01:57:30 MDT Print View

as to location/postion of the solar panel:

keep in mind, i believe - you might want to check this out, you want the angle of incidence of the sun's rays striking the solar array to be as close to 90 deg as possible for max. output.

my experience with solar cells is limited to the following:

played around with solar cells for a couple of science fair projects (burgler alarm & a po'boy's "laser"-inspired communication device, used a 5D cell flashlight) when i was young kid in grade school (ok, i was a weird 11 & 12 yr. old) & it, i.e. angle of incidence, was true then. had heard that the astronauts were going to be using a modulated laser beam for communication. so, i figured broad-spectrum light would work too, but over a much shorter distance. six feet was easy to do with the lights in the classroom off.

not sure if anything has changed about solar cells in 40+ yrs.

Edited by pj on 09/12/2005 02:35:25 MDT.

R Alsborg
(FastWalker) - MLife

Locale: Southwest
Flexible Solar Panel for Hiking on 09/12/2005 02:19:10 MDT Print View

Usf-11 10.3w, 12v Flexible Thinfilm Mod
UniSolar Flexible Solar Panel Battery Chargers

Rated Power Watts: 10.3
Rated Voltage (Vmp): 16.5
Rated Current (Imp): 0.62
Unit Weight (lbs): 2.00
Dimensions (inches): 21.80”x 16.70”
Price: $137.00

UNISOLAR battery charger incorporates the same Triple Junction solar cell technology as the Uni-Power module. The flexible solar panels are exceptionally durable and are encapsulated in EVA and bonded and stitched to a cushioned, vinyl and foam backing material. The modules feature a clear Tefzel® front covering. Bypass diodes are connected across each cell of the flexible solar panel, allowing the modules (excluding USF-5) to produce power even when partially shaded.

paul johnson
(pj) - F

Locale: LazyBoy in my Den - miss the forest
Re: Flexible Solar Panel for Hiking on 09/12/2005 02:38:23 MDT Print View

much more advanced than 40yrs ago. might be fun to "play" again.

is the 2lb just the wt of the array, or does it include the fixture for holding/charging the batts?

jacob thompson
(nihilist37) - F
Solar panel, on 09/12/2005 03:25:30 MDT Print View

I'm not sure what brands we have here in Australia but my friend and I that are Thru-Hiking PCT will be investing in one of these for the sole purpose of charging a video camera. We intend to make a semi doccumentary about our trip for both personal use and to distribute freely to other hikers with similar ideas.

I know Of one place here that sells them so I might drop in tomorrow and see if I can't find out the stats and post them up.