Need to power Mobile-Phone

 Hello,

I want to feed my mobile-phone with electricity using a solar-cell
system. This is a pretty exotic thing, that I have in mind and it's a
first-timer.

For this I need

a) specially shaped solar-cells, shaped to my own desire.
b) the formula to calculate my energy-needs.
c) a little advice on the rest.

I found it difficult to find an introduction on the web, that is to the
basics and generic enough, so I could draw my conclusions. Most texts
are about ready-to-use industrial solutions, and their employment etc.


--
Cheers, Andreas

 

  This is not PV, but at the recent CES show some company had a cell
phone recharger that was nothing more than a couple AA batteries. When
your phone ran out of battery power you could plug this in and rapid =
charge
them. I thought it was pretty clever, for being so simple and effective.

 says...

I saw something like that at a supermarket this week.  Basically
a box to hold 4, AAA torch batteries, with some adapters to plug
into various phone power inputs.  I think it was less than ten
dollars.

So for a really cheap way to your phone by PV, you could use that
item, plus one of those little solar-powered chargers for that
size battery.  Despite the long charging time, it could work out
if you don't use the phone very much.


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 Andreas M. wrote:

Charging a cell phone using solar PV is hardly exotic.
You can buy a wide variety of solar cell phone chargers.

... just a few samples of the hundreds of products out there...
http://www.modernoutpost.com/gear/details/mv_solarpanel.html
http://21st-century-goods.com/page/21st/PROD/SM400
http://www.costco.com/Browse/Product.aspx?ProdID 099302
http://www.tenergybattery.com/index.asp?PageAction=VIEWPROD&ProdID 6


Solar cells are typically flat and crystalline (glass). You can,
if you are really careful and have the right tools, cut them to
whatever shapes you desire but most people have no problem with
square. Exotic, flexible and other kinds of cells exist but they
are going to cost a lot more and will be less efficient.


Same formula as for any solar PV system.

Start with how much energy your device uses. Most cell phone
batteries have their capacity and voltage clearly printed on
them.

For instance, the Nokia 8360 battery is 700 mAh, 3.6 Volts.
mAh is mili (1/1000) Amp Hours. Watts = Amps x Volts so this
battery (when new) holds .7Ah x 3.6V = 2.52 Watt-hours.

I don't know exactly the run time this gives on that phone
but let's call it 2.52 hours to make the math easy. You would
need a solar PV cell that produces 1W if you want to use the
phone indefinitely in strong sunlight. Somewhat less if you
don't mind letting the phone charge a while between calls and
somewhat more if you want to quick charge during breaks in the
clouds.

The math goes something like this... The STC rating of the
panel needs to be derated anywhere from 10 to 20% because the
real world doesn't match test conditions. Figure another 5 to
10% (or so) loss from the charging circuitry in the phone. Then
figure out how many hours of bright, direct, full noon, sunlight
you are willing to let the thing recharge.

For instance, if you want to recharge that 2.52 Wh battery in
4 hours (all day in most places) of noon-sun then you need
(2.52Wh /.80% / .90% / 4h=) .875 Watts.


My advice, cell phone networks don't extend much past civilization.
Anywhere there is civilization you will typically find some source
of electricity. Get a good universal charger (110-240 Vac) and a
car charger (12V) and recharge when the opportunity arises.

If you simply must have a solar PV charger then buy any of the many
models already in existence or buy a larger 12V panel, charge regulator
and deep cycle 12V battery and run any kind of 12V appliance.

Anthony

 On 03.03.2006 09:15 Anthony Matonak wrote


[weblinks, very nice technical advice]


Thanks a lot, Anthony ! I appreciate your help very much. I can clearly
use your descriptions to do my own calculations now.

This is about a personal project, that I want to realize,
proof-of-concept, so to say. I am not skilled in in this area, so it's a
challange to me. A little adventure, then and when, so I can level-up my
views on the things that surround me.

--
Cheers, Andreas