Greetings, first time here.
Did anyone here try to build 100% solar powered Raspberry Pi?
It crossed my mind and powering it using solar power isn't too hard, main problem is how to power it 24/7, i'd obviously need some kind of battery for that. I'm interested in options, what batteries to look for, what to avoid, any recommendations?
Is there any site with some specific math for my problem?
Venture 30 Recharger + Nomad 7.
>>954333
/thread
>>954323
Those 2200mA phone charger batteries are used as a back on my Rpi server. Not solar powered but for $10 you cant beat almost 6 hours of battery life and you can daisy chain them together
>>954631
The only problem with those phone charging batteries is that most of them won't accept a charge while you're drawing current from them.
This isn't a problem with the batteries themselves, just a cost cutting measure in the control circuitry, since most users won't need to use them in this way.
USB backup batteries that advertise this as a feature, or are specifically designed for use with a solar panel, will be a necessary part of OP's RBP solar system, since power directly from the panel will not be stable enough to run a computer off.
I think someone suggested the Nomad 7 above. This won't be enough power. It looks alright on paper (7w=~1.4A@5V), but you can't count on getting 80+% rated power out of a solar panel all day long. I'd recommend the Nomad 18 (I think that's the one)if you wanted one from this brand.
If you wanted to run the computer 24/7 you'd probably be looking at a 30W panel attached to a 20,000mAh(@5V) battery pack (at a minimum) . Even then a few cloudy days could end up draining your battery.
>>954323
Math is pretty simple. RBPi draws 1000mA at 5V, that's 5W.
That means you need 5Wx24 to run it for a day, that's 120Wh per day.
Assuming your solar panel can get maximum sun for 5 hours a day that means you need at least a 24W solar panel, but with power losses from charging and discharging a battery, and to account for less than ideal weather you're going to want to double that.
You're probably going to watch a bit of a safety buffer with your battery, so a 20Ah (12V) deep cycle battery will give you 48 hours of run time, less the efficiency loss from the 12-5V transformer.
>>954323
>>954323
Hey, hey dude, *takes bong hit* you know how like solar cells are silicon man and microchips are made of silicon. What if you like get a semiconductor wafer and like etch an SoC and some memory on it, then like make the rest of it a solar cell.
You could like have a raspberry pi that is a solar cell.
Fuck I'm high right now.
>>954655
I suppose you could theoretically make a processor microchip that was also a solar cell on some layers. It wouldn't generate enough power to run itself unless the die was huge, it would have to generate only a tiny amounts of heat since it can't be encased in metal and it's not something you could DIY, but in the future I can envisage devices which look like a small sheet of ultrathin tinted glass that contain a transparent e-ink display and a ridiculously oversized low density silicon die the with PV layers and processing layers through.
This isn't possible with today's technology though, so people will probably call us both retarded.
>>954688
The most similar thing to this today would probably be the transparent PV cells used on watch faces.
Can this thread be about the new Raspberry Pi 3 that was released yesterday?
>>954333
>Nomad 7
As i see it it only collects 7W of power, not nearly enough for rpi to run 24/7
>>954734
This is /diy/. We don't buy here.
If you need solar power just buy a bunch of unsoldered solar cells off ebay and wire it to a beefy battery. You can make it as big as you want to meet your requirements.
Before you start any of that tho you need to know how much power you really need. Some Pis use more amps, others less. Peripherals attached draw energy too. Calculate exactly how much you need and then add a small % as a safety margin. Then design a solar system that can charge a battery that provides 5 watt and has enough amp/hours to last 48 hours.
>>954323
I have heard of this before but never really got into it. It recently sparked my interest and i am impressed by what people can do with it.
Just a little question.:
Lets say i want to be a cheapskate and want to use 1 pi for more then one project. is it just as easy as swapping the memory-card or is there more reprogramming required ?
So I'm wiring this tomorrow... I have a 20w solar panel and a 12v 7AH SLA battery.. I'm using 2 usb ports and ethernet, the camera and hdmi.
The camera is 250mA. (official docs)
The board is about 500mA (with high cpu usage,ethernet,usb peripherals, http://raspberrypi.stackexchange.com/questions/341/whats-the-current-draw-and-supply-voltage-tolerance).
So 750mA at 5v, 3.8W. My 7A 12V battery => 84W. Does this give me up to 21 hours of power? With a 20W solar panel I should have more than enough, right? I'm using those $1 switching power convertors from ebay to go 17-22v (panel) => 13.6v (battery) => 5v (raspi)
>>955796
It's the same as swapping the primary HDD in a computer. There is no difference between swapping the SD and using a different Pi.
>>955804
ok, thanks for the quick response.
well i guess i am off to buy a Pi then :)
>>955803
20w should be reasonably safe, provided it's sunny and you have a good angle.
If it's cloudy for a couple days or you get some shade for part of the day you might start running into problems, and 21 hours of battery runtime doesn't give you a lot of buffer.
>>955814
Oh. And the idea would be to record 3 hours a day; 5 days a week. The other 21 hours the rpi would be on but idle. That gives me about 330mA during 21 hours a day and 750mA 3 hours a day. Averages to 382mA, that's 1.9W... that would giveme about 42 hours then, that should be enough, right? I can turn it off during those 21 hours but the button to turn it on is very high and it's a fucking nightmare to do
>>955803
Remember that charging the battery is going to be less than 100% efficient, say 90% maybe. The stepdown converter will also be about 90% efficient.
100W would probably be a better estimate for power consumption.
>>955822
Oh, well if it's only running full power for 3 hours a day that changes everything. Your power consumption is less than a third of what I was calculating.
Yeah, that should be enough power.
>>955824
Sorry, I can't math at this time of morning, I meant to say ~5W power consumption, but that was assuming 24hr full power, since you've amended that to three hours, your actual power consumption will average closer to 2W.
This is taking into account both voltage stepdown and the battery charging inefficiency.
In any case, with 2W power consumption an 84Wh battery with a 20W solar panel should be more than enough.
