Solar panels
Post, Mark
mark.post at jcu.edu.au
Thu Jan 27 16:01:26 UTC 2011
Hi All -
I'll add two cents from the mountains, where I'm trying hard to be minimalist: Solar Traveller (UK) has come out with some reasonably good Li-ion batteries called "Power Gorillas" with lots of included adaptors (but make sure you get the right one for your laptop) and variable output 8v/9v/12v/19v/24v (would be nice to have a 5v, but oh well). I power a Lenovo x61 8cell to about 80% with one full charge, which gives me 5-8 hrs using Toolbox and MSWord on low-power mode (about 4-5 if transcribing), and if I had the money to buy one of the new solid-state Lenovos, I'd presumably have more. With two Power Gorillas, I have enough additional power for 12v AA/AAA and camcorder battery chargers via car lighter adaptors (included with the Gorillas), and don't need AC at all (so no inverter). And the Power Gorillas can take a 20v input, so I don't need a charge regulator (unlike with a lead acid battery). Power Gorillas are designed to work with 20w "Solar Gorilla" solar panels, which, however, in the mountains (no more than 5 hrs peak sun) don't give me enough charge even when daisy-chained. Also, I've found that they don't work well by directly-inputting into some laptops, despite that this is what they're designed for, especially when 19v laptops are powered-on. However, I've found that a 60w flexible panel well-placed charges one Solar Gorilla in about 3 hrs of peak sun, and another 1-2 hrs gives the other a good run. So far, I haven't run out of power yet, and I'm using everything pretty heavily.
So the setup I'd recommend for people interested in avoiding lead acid batteries and firm solar panels is:
1) 60w flexible panel
2) 1 or 2 Power Gorillas, depending on peak sun hours at field site, plus any add'l adaptors needed
3) 12v chargers with car lighter adaptor cables for AA/AAA and camcorder batteries, of which cheap copies (buy some backups!) are available on Ebay etc.
The whole setup weighs about 2-3kg not including whatever laptop you have, but is a bit pricey at about AUD $1000-1400 depending on where you buy everything. So it is really a reasonably well-funded fieldworker's set up rather than a practical community-oriented solution.
One additional point is that this setup doesn't work very well for Mac users, as Macs can only run off the Power Gorillas (via a car lighter adaptor), and can't charge the internal battery. This seems to be an Apple design quirk which probably won't go away.
Cheers from Arunachal,
Mark
Mark W. Post, PhD
Post-Doctoral Research Fellow in Anthropological Linguistics
James Cook University
Cairns QLD 4878 Australia
TEL (AU): +61-7-4042-1881
TEL (IN): +91-89746-64180
http://jamescook.academia.edu/markwpost
***I am on fieldwork in Arunachal Pradesh until late April 2011 and can (hopefully) be reached on +91-897664180. Keep trying.***
________________________________________
From: r-n-l-d at unimelb.edu.au [r-n-l-d at unimelb.edu.au] On Behalf Of Xavier Barker [meibitobure.gaunibwe at gmail.com]
Sent: Thursday, January 27, 2011 5:44 AM
To: Aidan Wilson
Cc: r-n-l-d
Subject: Re: Solar panels
Spot on! Check him out on http://www.servalproject.org/
<http://www.servalproject.org/>
On 27/01/2011, at 10:56 AM, Aidan Wilson wrote:
This (the stuff on the finemespot.com<http://finemespot.com> website, not the lab-in-the-case stuff) seems reminiscent of an invention I saw on the New Inventors (ABC Australia) about this system, in which a portable mobile coverage tower is rolled out to areas after disasters (Haiti was the most recent disaster at the time and was the cited example) which would allow people to connect to one another and call emergency numbers while the normal towers are non-functional. The benefit of the system was that users retained their regular numbers and could therefore call one another in the effectively closed system. And calls inside the cell network are free since it never goes to a telco.
I'm going entirely off memory here, so I might be getting a couple of details wrong, and can't remember what it's called. And I'm also getting significantly off-topic...
--
Aidan Wilson
PhD Candidate
Dept of Linguistics and Applied Linguistics
The University of Melbourne
+61428 458 969
aidan.wilson at unimelb.edu.au<mailto:aidan.wilson at unimelb.edu.au>
On Thu, 27 Jan 2011, Xavier Barker wrote:
Hi all,
As always, i can offer no practical fieldwork advice, but...
Our company provides small mobile internet connected computer labs in a suitcase (or, rather, pelican case) to a number of schools
in off-grid parts of Uganda. We fit 11 netbooks with 9 cell batteries and a single loom charger. Most netbooks are designed to
draw 19V, but we have no problem at all fitting the loom directly to a 12V battery and providing DC power. With this
lab-in-a-case, we are able to provide fully internet-connected(3G/gprs/edge/sat (with a SPOT
(http://www.findmespot.com/en/index.php?cid=116)) to places that have no power. The system is able to be used for about 5 hours
without a charge, but a whole day oif trickle charging from solar. Whilst this solution works for getting everything charged at a
base station where solar panels can be permanently fixed, there are also a number of really good portable options. Keeping in mind that the netbooks will run fine on 12V DC (as will small desktop PCs like the Eee Box which can be fitted with a DC
LCD monitor), it is possible to rig a 12V folding solar panel directly to the charger of the netbook. Suntech make small folding
60W 12V panels but they still weigh about 15kg - not great for lugging around. ALternatively, and much better if weight is a
concern, is the 20W solar-charging laptop bag
(http://www.multipoweredproducts.com.au/products/Voltaic-Generator-%252d-Solar-Laptop-Charger-Bag.html). This bag has batteries
which will bring your netbook up to a full charge in a day, provided you get about 5 hours of sunlight. It's probably not going to
be enough to charge a full-sized laptop though. It also has outputs for you to connect 5V USB devices and car-plug options. This
means you can plug in a caravan/car/camping style lamp into the case at night and give yourself plenty of power. Cheers,
Xavier
On 27/01/2011, at 4:06 AM, Jeremy Hammond wrote:
Hi All,
I am pretty much in agreement with Tom and have being successfully doing a
similar setup for the past 3 years in Vanuatu. I also buy lead acid
battery in-situ but am considering getting a solar-specific one this year
if I can find it in Port Vila. I'll just add 3 points.
1. Buy a universal battery charger. They are great and means you can
really cut down on the amount of chargers you have to take (I.e.
phone/Camera/AA/video/AAA/USB are all doable with mine). Here is one
http://www.solartechnology.co.uk/shop/camcaddy-cc1005.htm but there are
different brands/models. You can buy them at most camera stores. I just
have two of these for all my charging needs (plus my laptop charger of
course).
2. Consider getting solid panels. If you have easy enough access to your
fieldsite and have a long term relationship with them then it is an easy
process to take it there and set it up on a roof etc. I usually take a
solid 50W panel with me each time I go so that now I have around 150W
which should be above 200W this coming year. They are super strong, and
great long term value. Plus now I leave them there setup with LEDs on the
battery so that people there can use the light at night, even when I'm not
there.
3. While tom suggested the "workman's" light and they are good, if you are
electrically handy then making your own LED setup is really inexpensive
and easy. There are some great yellow ones that are good for
reading/working by as well. On that note as Tom said, test your setup but
also understand how it works. Get a friend who knows something about
electronics to explain it to you and when things go wrong, you will be in
a much better position to fix it.
Jeremy
-------------------------------
Jeremy Hammond
Syntax, Typology and Information Structure Group
Max Planck Institute for Psycholinguistics
P: +31-24-3521171
E: Jeremy.Hammond at mpi.nl
W: http://www.mpi.nl/people/hammond-jeremy
On 26/01/11 7:27 AM, "Tom Honeyman" <t.honeyman at gmail.com> wrote:
Hi Jeff,
Despite the negative "reality check" at the end of the paper Pat
mentions (thanks Pat!, also the paper supersedes the blog posts, but
thanks Peter!), I am now quite happily using solar power for fieldwork
in Papua New Guinea.
My current setup (well actually I've dropped/genericised/forgotten a
few items to simplify!):
1 low power netbook (they're all almost exactly the same)
2x DC adapter for netbook, but also adapters to charge USB devices,
mobile phones etc also very good
2x Li-Ion battery pack chargers (for camera, video camera etc... can
be very handy)
1x DC-DC adapter with multiple plugs (very handy for powering all
sorts of things if you know what you're doing)
DC plug adaptors (so I can plug in many things at once)
50W foldable solar panel
charge regulator with load cut-off
10x AA NiMH AA batteries
8x AA NiMH AAA batteries
1x AA/AAA battery charger (charges 10 batteries at once, each
individually)
1x AA/AAA battery charger (charges 4 batteries in pairs - this can be
a pain if you have a device that uses 3 batteries!)
Head torch and mag-lite - make sure they work with rechargeables!
Often they don't work well with them.
12v/DC workman's light, fluro or LED based, low power consumption
(these are really good for a lot of light!)
All the regular equipment otherwise (recorders, speakers, mike,
cameras, etc), but make sure they work well with rechargeables).
And then I also pack the following for fixing stuff (but only if you
know what you're doing):
fuses, glass and blade with several spares for each device that has one
pack of alligator clip wires
Gaffer tape (often available in country)
digital multi-meter
pocket knife
jeweller's screw driver set
super glue (often available in country)
I tend to buy a (preferably deep cycle) lead acid battery in country.
This let me work for a few hours a day on the laptop, use torches/
flashlights at night, and put on a "movie night" once a week. Every
now and then an activity might come along (like a big recording
session, or very rainy weather, or on one occasion my roof blowing
off!), which would drain the battery too much. Then I'd have a day or
two not using the laptop (far and away the most power hungry).
4 things I'd recommend:
(a) check _everything_ beforehand. There are many "single points of
failure" in a solar setup. That's why its good to have backups, or
multiple ways of achieving the same thing.
(b) get a charge regulator with a load cut off. This magical box will:
- ensure that the battery is charged properly, dropping the power as
it approaches a full charge and cutting the power entirely when the
battery is full
- stop power flowing back into the panel at night (this is often
redundant depending on the panel)
- cut the power to your devices when the battery is too low
Basically this will let you safely run your equipment, but it'll
ensure that the battery doesn't fail because you've drained it too
much... this is something that is _very_ easy to do. If you know what
you're doing then you can drop this, but you'll spend more time
managing your power setup and less doing work.
(c) try to eliminate using AC power. This is costly. I guarantee that
you will not have enough power to do all the things that you'd like to
do. So this means do not use "wall adapter" plug equipment, use "car
adapters" for all of your equipment. The DC adapters for charging a
laptop can often power other equipment. The DC-DC adapter is extremely
useful for powering low power equipment. Having these flexible, multi-
plug adaptors can be very useful for unexpected scenarios like
powering a cassette recorder you've borrowed because your audio
equipment fell in the river. Or powering your recorder directly
because your batteries or battery chargers have failed for some reason.
(d) check that the AA/AAA powered equipment works, and works well with
rechargeable batteries. Rechargeables operate at a lower voltage than
Alkaline batteries. A lot of equipment is designed for use with
Alkaline batteries, and even though initially they may work fine,
later in the field you may discover that they have a (seemingly) short
life. Digital cameras often are designed to work with rechargeables
these days (sometimes they last longer with rechargeables), but
torches/flashlights for instance are often not.
Hope this helps,
Tom
On 26/01/2011, at 3:48 PM, Patrick Hall wrote:
Hi,
Honeyman also coauthored a paper with Laura Robinson on this topic in
LD&C which might be of use:
Honeyman, Tom & Laura C. Robinson. 2007. Solar power for the digital
fieldworker. Language Documentation & Conservation 1(1): 17-27.
It's available online:
http://hdl.handle.net/10125/1722
cheers,
Pat
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