Hi Simone,

We've had good success running netbooks off of solar power systems and
batteries. Look for the netbooks that advertise 8-10 hrs of battery life
since they will use the least power. You can buy a 12v car charger on
eBay for almost any netbook. Double check that a 12v charger exists for the
netbook you want though, there is often a lag between the netbook being
released and the car chargers being cheaply available. I'd get 2 in case one
breaks and make sure to bring some spare fuses for the charger. You can also
also get an iGo or similar 12v car adapter and use that. I'm not sure
how efficient any of those systems are compared to building one yourself
which is easy enough to do. Get a voltage regulator like this: (
http://www.dimensionengineering.com/anyvolt3.htm). Then go to Radio shack
with your charger to find the right size power tip for your computer. Some
of the older netbooks take 12v but the newer ones mostly seem to take 19v.
If you are charging the netbook off an external 12v solar charged battery,
the car charger takes care of up-regulating the voltage to 19v.

You can get a rough estimate of how much power your netbook uses by looking
in the specifications for the battery size (usually measured in milliamp
hours mAh, amp hours - Ah, or watt hours - Wh) and then looking
at estimated or tested run times. Divide the run time into the battery and
you get a measure of amps or watts the computer uses. If you can't find the
battery specs, look for replacement batteris for that computer, they often
list the battery amp hour size explicitly.  Knowing that also helps for
buying external batteries since it will let you estimate how much run time
you can get from any other battery system you buy. For example my ASUS has a
63Wh / 5600 mAh battery and runs 8-10 hours so at the lowest power usage it
will be pulling about 6 watts. I'd recommend 30% to all your calculations
since you're always better off rounding up when calculating solar power and
battery usage (i.e. assume everything will use power more than you
calculated and your solar will produce less than you thought)

We've used ASUS netbooks in very hot and very cold weather without problems,
but they are usually in a weather proof housing so I can't vouch for their
reliability in wet and dust.

You can buy well engineered battery/solar solutions that are designed for
expeditions - they are very nice but cost more than wiring something
together yourself.

The DIY version is to get some LiFEPO4 battery packs - they are light (as
batteries go) and last a couple thousand charges. Here's one option:
http://www.batteryspace.com/128vlifepo4batterypacks.aspx). Make sure you get
a solar charge controller that's designed for those batteries. Also, note
that the fully charged voltage on LIFEPO4 batteries can be 14v or higher so
make sure anything you plug directly into it is rated up to 15v (or whatever
you newly charged battery is putting out).

Some prefab battery and solar charging systems:
http://www.goalzero.com/
http://store.bruntonoutdoor.com/portable-power/
http://www.humanedgetech.com/shop/home.php?cat=4


Hope that helps.

Tim


---
Tim Brown
http://Time-science.com <http://time-science.com/> - Innovative Image
Technologies
http://www.gigavision.org - Gigapixel timelapse systems
[email protected]
Office: (801) 893-1314 | (866) 411-3836
Cell: (801) 554-9296



On Thu, Apr 28, 2011 at 8:16 AM, Simone Whitecloud <
[email protected]> wrote:

> I'm looking for advice for bringing a laptop-powered hand-held
> photosynthesis system into the backcountry. It's a CI-301. Any advice would
> be greatly appreciated. I am considering purchasing a netbook because they
> are light weight and affordable. Any experience doing this? I work in wet
> and windy conditions with occasional sunshine, so I'm a little worried about
> dust and moisture.
>
> Also, I would love advice on light weight systems for solar charging a
> netbook/laptop.
>
> Thank you!
> Simone Whitecloud
> PhD Candidate
> Dartmouth College
> New Hampshire 03755
>

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