Prototype PLOTS Portable Energy Scavenging Kit

[Don Blair]

Hey Folks,

This weekend Ben Gamari and I hacked together a first version of the PLOTS Portable Energy Scavenging Kit.  If you get the chance, do check out the photos and ingredients at our research note, here:

http://publiclaboratory.org/notes/donblair/12-17-2012/portable-energy-scavenging-kit-01a

Our planned next step is to design a custom PCB that will allow for charging different battery types (LiPo, rechargeable AA), as well as different output voltages (to accomodate cell phones as well Raspberry Pis).  

If you visit the research note, please free to comment with thoughts re: how future versions should look ... and what they should do ...

Cheers!

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[Jeffrey Warren]

cool... this could be used in conjunction with the raspberry-pi-based hackable camera for long-term timelapse photography...

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[Shannon Dosemagen]

Really excited, we were trying to get a time lapse camera together to try out at LUMCON, but the energy part was one of the hold-ups. 

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[Don Blair]

yes, that'd be really neat!  don't know what the power requirements of the R-Pi are, but for long-term projects we might want to figure out how to put it in 'sleep' mode when it's not taking a picture ... i think there are some distributions of embedded linux that nicely allow for this ... will look into it ...

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[Jeffrey Warren]

I think your friend Craig knows more -- but i think it just needs USB power and will "go to sleep" on its own if nothing is happening.

[Don Blair]

Yep, Craig is the local linux expert ... i'll ask him ... and you're right, if the R-Pi can just go to sleep (makes sense, in that laptops running ubuntu can do this quite readily), then we're good to go!

Shannon -- what kind of camera were you interested in using at LUMCON? The current setup can power an Arduino, no problem -- and an Arduino can be put into sleep mode ... so we could have the device wake up every X minutes, snap a photo (via a JPEG camera attached to the Arduino, or by triggering a Powershot via CHDK), go back to sleep ... 

Right now this thing can power an arduino, no problem, and a recharge a cell phone.  But Ben had a cool idea re: developing a programmable (arduino-based) circuit that allows you to charge more than one battery type / chemistry at once, and output more than one voltage+current combo.  This means that in the future, we could maybe:

a) power an arduino

b) charge a powershot LiPo battery

c) charge rechargeable AA's

d) power an R-Pi

e) power an LED lamp

... all with some solar cells, in the field.

The other aspect re: all of this that excites me is the idea of getting people to start going off-grid for certain daily things (like charging their cell phone, LED lighting, etc) ... here's a cool recent article that gives one hope re: the ability of renewables to provide all of our energy needs in the future:

http://arstechnica.com/science/2012/12/the-grid-of-2030-all-renewable-90-percent-of-the-time/

Also, if you need some pleasure reading over the break, there's a fantastic (free) book on how sources of renewable energy can add up (or not): 

http://www.withouthotair.com/download.html

[Shannon Dosemagen]

We were using a plant cam, but this was last year, so taking it in a different direction is fine. 

[Patrick Coyle]

Don, interesting start and you've already got numerous applications identified. Terrific.

[R.J. Steinert]

The R-Pi pulls 0.2A and then 0.4A when Ethernet starts.  Now that Model A's (NO ETHERNET) are starting to come off the assembly line, you'll be able to get it to run at 0.2A.  Running an R-Pi on a battery can sometimes result in killing your SD Card.  Read more about it in my post here -> http://rjsteinert.blogspot.com/2012/12/how-to-build-death-trap-for-sd-card.html

[Mathew Lippincott]

The arduino's sleep mode still draws signficant power to run the internal clock.  it has a deep sleep mode that can be awoken from a pin by an external clock.  I would recommend building in a clock chip like the DS1307.  there is another clock in that series that is surface mount but comes with a full alarm function.