Hello everyone. I'm a student currently taking licence on computer
engineering.
I recently grown interest in making a solar powered server. Having a
clean home-made server to host a webpage (or even a game server!)
fascinates me.
Then I discovered Beagle Board. Low powered consumption board! With
excellent capabilities if you will. But I'm kinda new to the area and
I was wondering if it's even possible. My budget is of a typical
university student.
Do you ever built a server (linux most likely) with beagle board? How
do you power your server? Do you ever used solar energy to power
beagle board? How does the power/energy thing works (how many watts do
i need, how do I need fry the board out?). I know little and your help/
commens would be appreciated to make my project come true!
I'm convicted in hosting a webpage with detailed explanation if
everything works out.
Seems I can't edit my message and so here's the errata of the message
I originally posted:
Where you read (how many watts do I need, how do I need fry the board
out?) it should have been (how many watts do I need; how do I know I
won't fry the board out?).
Seems I can't edit my message and so here's the errata of the message
I originally posted:
Where you read (how many watts do I need, how do I need fry the board
out?) it should have been (how many watts do I need; how do I know I
won't fry the board out?).
The board can pull up to about 10W assuming no power management. If you are
running headless, you can knock that figure down a bit by disabling the DVI
xmitter.
The baord really wants no more then 5V or bad things can and will happen. I
have had luck getting it running down in the 3.5V range. Prehaps a zener
diode to protect the board and 4 NiMH trickled from a panel might work?
From an earlier email I understood that without the display the power
would be merely 2 watts.
The OMAP3530 has sophisticated methods for power control so you can
switch of most of the modules that you don't need.
This requires skillful low-level programming.
For regulating the solar power voltage you should use a low dropout
linear regulator or better yet a high efficiency switching regulator.
Could you measured the power of the board when it works at the minimum frequency, sleep/idle mode,... that is, in the configuration that give the lowest consumption?
Amazing. From your calculations and suggestions I see you didn't
consider using a battery, specially if it's a server, the solar
charger won't be charging much at night and the board will probably
need to use power from a battery. You guys have any recommendations of
what batteries are most appropriate?
@Seppo: Yes I'll hopefully be looking into the wonderfull
documentation of the board and try to do that. As for your suggestion
to regulation the power voltage, can we consider having the battery
instead? That means I have to regulate what comes out of the battery
right?
@Alfredo: That's really low haha.
@Hunyue: I read somewhere it has a potential maximum limit of +5.5
volts or it will go boom. What if I use a battery?
Thanks for your answers guys, there's still much to plan yet!
Amazing. From your calculations and suggestions I see you didn't
consider using a battery, specially if it's a server, the solar
charger won't be charging much at night and the board will probably
need to use power from a battery. You guys have any recommendations of
what batteries are most appropriate?
Pb batteries are cheap and easy to find, plus they often are very
forgiving on the inputs. On the other hand, they are obviously heavy
and don't give the best power/size ratio.
The buzz today are on Li-Ion batteries, they have the best power/size
ration, they weight less, but they explode if not charged properly.
Here (http://farm4.static.flickr.com/3248/3019769513_1ed0833cfe.jpg)
is a picture of the 9 cell battery of a 9 inch netbook. That battery
holds around 60W of energy, and that's around 12h of power if you stay
under 5W.
@Alfredo: That's really low haha.
That figure seems good to me, that's why those SoCs are fantastic.
@Hunyue: I read somewhere it has a potential maximum limit of +5.5
volts or it will go boom. What if I use a battery?
Many solar panels and controllers work with 12V batteries. I guess you
will have to use (find) a step down regulator, that will make sure
that you never feed more than 5V to the board.
If you are patient I would recommend a rechargeable Zn-Air battery,
see www.revolt.com. It has the best energy densities - when it will
become commercially available.
If yo cannot wait, I recommend Li-ion chemistry. It is the power of
modern cell phones and notebook computers. There are special charger
chipss available just for Li-ion batteries, use one of them. You
should connect enough cells in series to get some 6 V of voltage from
the terminals. Using a low dropout linear regulator you can then get
an accurate 5 volts for your Beaglegoard. Li-ion AA size cells come
with capacities well ower 2 Ah so they would power your board for two
hours without charging. And much larger size larger capacity cells are
also available. Just be warned, your cells can easily cost more than
the Beagleboard... As I think of it, a spare notebook Li-ion battery
might just be the easiest solution for you. Get one with the highest
capacity and a nominal voltage no less than 6 V. Then make the
Beagleboard 5 V with a fixed voltage 5 V low dropout linear regulator.
The solar cell should be able to produce say 9 volts and 5 amps so you
can charge some 30 Ah during the day to cover the consumption during
the night with a little of spare electricity. All this will cost you a
nice sum of money!
Good luck for your interesting project!
Keep us informed on your progress,
siñ
Thank you for your kind, descriptive answers. I'll make a list of the
components I think I'll be buying for this project and post here so
you can see and tell me what you think about it. I'll do some reaserch
on the batteries.
Beagle board won't need more than 5V even if it's getting alot of
webpage requests or hosting a game? Do you think I'm going to need
another link of power to the mouse and keyboard and the ethernet
connection? (I'm thinking of a USB hub for these?)
I'll make sure to make a webpage if the project goes well!
Please keep in mind that Ethernet and USB are very power hungry! You
should calculate some half an ampere of 5 V for each. So they can
easily use as much as Beagleboard and cut your battery time to half!
KB and mouse are relatively low power.
siñ
One more idea. Please get the brand new Linear Technology LTC3108 data
sheet (www.linear.com). It has some interesting features helping to
harvest energy from heat and solar cells. But the illustrated
applications are far from what you are aiming to...
siñ
Is a battery capable of powering the board and then in another cable
the USB hub? Or do I need two batteries?
I think what youn are trying to say is that the USB hub will most
likely waste much more power than the board?
I'm starting to think this project is way more complex than I
inicially thought. Been reading the board's reference manual and I
feel I don't have enough knownledge to complete it... it's sad
though...
One battery is enough. The consumption of the HUB directly depends on
how much current the devices attached to it will draw. The allowed
maximum is 500 mA, so each port can take up to 2.5 W.
siñ
OMAP makes your task simple as it was not meant to extremely low power
applications though it _is_ a low power uC, just not that low. Solar charging
is fine but you need a bit more reserve power than an amp hour to cover nights,
cloudy days and less than optimal panel facing.
But you don't need any of that.
You mensioned that you dream of home made server. I suggest you to study 'Power
over Ethernet'. The solution may as well be just a bogus ethernet wire that
feeds power to your board. You do have to examine the voltage level, and likely
regulate it to guarantee that it does not go above 4,5V (TPS65950). The ideal
level is 3,6V. Check the datasheet.
