Jasont41
Posts: 70
Joined: Fri Nov 11, 2011 1:22 am

Re: Would this work?

Thu Nov 24, 2011 8:49 pm

A little background: I am very environmentally conscious, the main reason I am going to use the PI as my main pc is because of the low energy usage. I need to find a way that I use as little resources as possible, but I am not sure if that is even possible.

Would this work? http://www.amazon.com/Instapark%C2%AE-H ... 231&sr=1-8
I would like to eliminate the power usage of thge PI if at all possible.

Thanks in advance:P

wrhii
Posts: 66
Joined: Fri Nov 18, 2011 1:47 am

Re: Would this work?

Thu Nov 24, 2011 9:09 pm

From the link, it looks like it would not provide sufficient power.
[quote]Maximum power voltage ( Vpm ) : 17.5V ;Maximum Power Current: 0.28A[/quote]
The Pi needs 5V DC + ~700ma as I recall, so you\'re about a half amp short, and dangerously over voltage.
After some searching ChinaVision has a device which might put out enough, depending on how heavily you tax your Pi...

rotmoset
Posts: 9
Joined: Thu Nov 24, 2011 8:32 pm
Contact: Website

Re: Would this work?

Thu Nov 24, 2011 9:14 pm

I would say that this is useless. The power consumption of the rasp-pi is already ridiculous small.

For example I just calculated what the monthly cost of having it running 24/7 was and it comed out less than 30 cents. Cooking spaghetti on your stove will probably use more power.

Just sayin\'.

wrhii
Posts: 66
Joined: Fri Nov 18, 2011 1:47 am

Re: Would this work?

Thu Nov 24, 2011 9:50 pm

While the idea may seem useless, the idea of it running off of solar would be ideal for some areas (less developed countries) where reliable power is ... not an option for everyone. As a result, having a strong enough solar cell, turbine, water wheel, whatever would be a great addition to the community.

Jasont41
Posts: 70
Joined: Fri Nov 11, 2011 1:22 am

Re: Would this work?

Thu Nov 24, 2011 9:57 pm

It\'s not whether it is useless or not, it\'s about my obsession with using the least possible resources. Call me crazy :P

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Vindicator
Posts: 314
Joined: Sat Sep 17, 2011 11:10 pm
Location: Susanville Ca USA
Contact: Website

Re: Would this work?

Thu Nov 24, 2011 10:24 pm

17.5 volts X .28 amps = 4.9 watts so at max the power is sufficient for the Raspi while yet way over voltage but if you run it to battery charger and use the batteries to run the raspi the end result would run the raspi fine and do so when the sun was not out.
49 watts for a 10 hour charge day of sun light.
Just a little imagination can solve this one LOL.
http://www.amazon.com/Solar-Panel-Charg ... d_sim_ol_6
combine with the above charger and a battery and run raspi from a micro usb car charger and you have a self contained Raspi system.
would be a little bulky for mobile use mattering the size of battery you choose but could all could be fit into a briefcase.
If you are more worried about ,spelling, punctuation or grammar you have probably already missed the point so please just move on.

radu
Posts: 110
Joined: Mon Nov 21, 2011 8:19 pm

Re: Would this work?

Thu Nov 24, 2011 11:19 pm

Forget Amazon.
Go here: http://http://www.goldmine-elec.com
They often have solar panels on sale. Get some 6V ones, make sure you get enough so that you get something like ~5A when put in parallel. You will want to buy some batteries too, because you are not going to have sun every day. And probably a switching power converter.

PenguinCraft
Posts: 3
Joined: Thu Nov 17, 2011 2:41 am

Re: Would this work?

Thu Nov 24, 2011 11:49 pm

Not a bad idea. but you would probably need multiple panels and a large lipo battery to make the most of the panels. http://www.adafruit.com/category/67 has several options. their panels output 6v and the batteries 4.7v so you will need to regulate the power somehow.

Skygod
Posts: 211
Joined: Wed Sep 21, 2011 7:22 am

Re: Would this work?

Fri Nov 25, 2011 7:38 am

[quote]Quote from wrhii on November 24, 2011, 21:09
After some searching ChinaVision has a device which might put out enough, depending on how heavily you tax your Pi...[/quote]

The spec sheet for this would indicate that the power output would be an issue

Output (V): 4.2/8.4/12.6/16.8/19V

Assuming the 5V indicated on the front is actually the 4.2V in the spec, then the output, then there is another problem as the output at 4.2V is only 500mA. (Not enough juice for the Pi)

Output (A): 500MA/4.2V, 800MA/8.4V, 1000MA/12.6V, 1000MA/16.8V, 2000MA/19V

brandonduda
Posts: 10
Joined: Fri Nov 25, 2011 8:38 am

Re: Would this work?

Fri Nov 25, 2011 8:40 am

Use a PWM? (Pulse Width Modulator)

or:

Find the right resistance to make the voltage 5v.

Skygod
Posts: 211
Joined: Wed Sep 21, 2011 7:22 am

Re: Would this work?

Fri Nov 25, 2011 12:50 pm

I believe that if you\'re looking to power the Pi 24/7 using solar power alone, then you\'ll need the following components :

Solar Panel (to charge the battery)
Charge Controller (to avoid overcharging the battery)
Battery (to store the energy)
Regulated DC - DC output (to provide clean power to the Rpi)

If you\'re looking at a \'full tilt\' Pi then you\'ll be using 5V @ 700mA x 24 hours = 84Wh a day.

Generally, solar calculations are based on 5-6 hours of sunlight per day, so a minimum of a 17W panel will be required, however it\'s best to assume just 80% efficiency, so look for a minimum of a 23W panel.

The battery should be of a deep cycle style (mainly used in Marine / Golf Cart implementations) as a standard car / motorcycle battery will be killed off quickly if your draining it regularly.

Sizing the battery will depend on how many days you might expect to have no solar generation due to overcast conditions. Here in Thailand, I would only allow for 1 \'wasted\' day, but will assume 2 for general purposes.

Assuming you choose a 12V battery, you\'ll need 84Wh x 2 (days) / 12 Volts = 14Ah battery.

As you will not want be draining the battery too much, ( >50% regularly will reduce battery life), look to scale the battery up to maybe 30Ah

You can then hook up a car DC-DC Regulated Adaptor (Basically the units that plug into the car cigarette lighter socket) and connect this to the RPi using the Micro USB connector.

When you actually start adding up the costs for powering a single small device, you\'ll probably find yourself with a bill for a couple of hundred dollars and the battery will need to be replaced every 5 years (if you\'re lucky).

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