Re: Discuss: Solar Charger & battery pack for the Raspberry

n1mie
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Re: Discuss: Solar Charger & battery pack for the Raspberry

Postby n1mie » Tue Jul 09, 2013 4:20 pm

I'm interested in the 1.5A panel/box combo. I'd be interested in what pricing you worked out to the US. Looks like you've got a great line of products here.

One of my future projects will involve a remote station with a Pi and a 2m ham radio. The device will monitor and relay radio packets as necessary. Would like to be able to deploy without wiring (except antenna).


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cottonpickers
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Re: Discuss: Solar Charger & battery pack for the Raspberry

Postby cottonpickers » Wed Jul 10, 2013 7:58 pm

N1mie: wow sounds nice:). I've yet to weigh and price a US one but as the first customer I'd be delighted to send one over for the price of a V9 model and use it to find the cost. If that works for you please order a v9 via the link and add a note to send the 1,5amp panel box holder fan combo. Future US prices will be higher but based on costs.

Muad.Dib
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Re: Discuss: Solar Charger & battery pack for the Raspberry

Postby Muad.Dib » Sat Jul 13, 2013 11:18 am

Hello there!

(please move me if not the correct forum)

@cottonpickers:
First I would like to thank you for inspiring me! (yes you did!)
It is basically because of you I learned about the pi all together, while I was searching the web to see where solar solutions for computers stand.
For quite a while now I was starting to get more and more interested into reducing the footprint of my 24/7 servers.
And it is how I landed on your website, saw where you were already with your ongoing projects.
So I ordered my first Pi and slowly gotten around it when I had some spared time. The linux part was not a problem as I already knew about it, however time, electronic/electricity knowledge is a whole other story :)

A DIY Solar powered Pi is so exciting!

That's why I am trying to learn about it step by step.

Right now I am at the very first step, and I would like to fully understand how that's work, and maybe you can share some lights on it.

From what I can see on your pictures it does not seem that you are using any complex charging circuits and have power directly goes to the cells acting as a buffer. Meaning depending on panel, current powers the pi and if anything is left, charges the battery? And when Sun source is failing the battery pack takes over until the sun comes back or the battery are depleted? Or did I misunderstood something here?

That's exactly what I am trying to figure out how to connect a battery pack to a source (source being wall plug or solar panel) to act as a buffer / ups if main powers fails.
I know that if power source is above C/10 it will damages the batteries, but that I dont really care because they are cheap and of course as long as they do not blow up :D
But if Pi is constantly drawing power from source, only what's left of power will go trough the batteries unless I am wrong again. I can easily adjust to a power wall plug which only delivers the current I need if that is 2A, 1,5A or 1A.
Of course batteries will constantly be 'on charge' since no circuit will cut down the power when fully charged, and that will likely reduce their lifetime but would that work without risking to turn my house into a bomb? :o

I hope I am not asking for any industrial secrets here as I am not planning to make any solar panels on my own just trying to understand something which I do not fully get so far.

Many thanks :)


--
Dib

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cottonpickers
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Re: Discuss: Solar Charger & battery pack for the Raspberry

Postby cottonpickers » Sun Jul 14, 2013 9:26 pm

muad.dib: Basically you've got it right. It might be helpful to think about a car battery that both powers stuff in a car (headlights, radio etc) and also gets charged (dynamo or alternator) of course, sometimes only one of these things is happening (its getting charged or discharged) but also some times they both happen at the same time (when its raining hard, and you have the lights , wipers and radio on) Think about how the alternator might switch on and off with the battery fluctuating in the middle, but keeping the voltage nice and stable for the car.

If you want to do something similar but not use a solar panel you need to apply a voltage higher than the batteries otherwise the electricity won't 'flow' to the battery. A NiMH battery says 1.2v on the side, but really it varies from 1v to 1.4v. Four of them in series therefore range from 4v to 5.6v The raspberry Pi actually works across this whole range (my Pi certainly does anyway) Now to charge a battery that is 5.6v you need to charge it with a higher voltage (just like the alternator of a car puts out more than 12v to charge it) something like 6v-6.5v would be good. This is slightly simplistic, but as you charge the voltage will roughly meet in the middle of charger voltage and the battery voltage. Hence you might say that the batteries 'hold down' the voltage of the solar panel or wall charger. You are right that only the 'spare' current will go in to the batteries. So if you have a wall charger that puts out 6v 1amp then the pi will take about 400ma and the rest (600ma) will go in to the battery. This will heat them up quickly as its more than 0.1C by some margin (0.1C is about 200ma) and because a wall charger will charge all day, every day 24x7. A solar panel won't be sat charging fully charged batteries for long due to cloud and nightime etc. So ideally you should likely go for something like a 6v 500ma wall charger.

Hope this helps.

In case it helps, the V7 and V9 models work pretty much as above, but the newer 1.5amp panel puts out 5v and is designed to be used with power packs where they regulate.

velcrow
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Re: Discuss: Solar Charger & battery pack for the Raspberry

Postby velcrow » Fri Aug 02, 2013 10:04 am

Hi cottonpicker,

What I have is -

1) An Otter family
2) Raspberry Pi model A + Camera Module
3) 3G dongle (Vodafone Huawei E177)

The Otter's have a routine, taking a certain path by the river, usually in the dawn hours (5 - 9). I want to setup a solar powered "Otter Cam" to record the activity on this river path and hopefully capture some images of the cubs!

At certain intervals (depending on power consumption) I would like the Rpi to "call home" using the 3G dongle and send on a selection of images (no video).

On the software side I will use motion to capture the video and create thumbnails, and it's these thumbnails I would like to send over 3G.

I get to visit this spot once a month so I'm looking for a setup that would be most suitable.

Your kits (the thread is a great read) seem like a perfect match but I'm not sure which version would best suit my needs (somewhat waterproof, long battery life etc) ?

I'm based in Dublin, Ireland so the weather conditions are just the same as the UK.

Thanks John

FelixofMars
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Re: Discuss: Solar Charger & battery pack for the Raspberry

Postby FelixofMars » Sat Aug 03, 2013 1:25 pm

Hi, How suitable would this be to run a small webserver from. I have no screen attached and only a few services. Would it be constant or would you need another method? I am based in the UK.

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cottonpickers
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Re: Discuss: Solar Charger & battery pack for the Raspberry

Postby cottonpickers » Sun Aug 04, 2013 6:11 pm

Velcrow: I think you likely need the 1.5amp / 1500ma set up (as its water resistant, and gives you strong charging) with a battery pack and a USB timer to switch the camera/pi on at specific times. The timer isn't available currently though (some issues occurred, that I'm working through) In the interim you could get the 1.5amp model with a pack to get you familiar, but it won't be able to run 24x7 with a camera and 3g dongle. I'm hoping to resolve the usb timer issue in the next 3 weeks.

Felixofmars: the idea of using the pi as a webserver is fine and doable. Its slow (of course) and depends what hours you need it running. Like the response to Velcrow, you likely need to consider the 1.5amp panel and likely need to restrict the running time (eg day hours only) or timed via a usb timer. The Pi Version A uses about 200ma every hour. so at night you lose about 12hrs X 200ma = 2400ma so you need to 'put that back' in and also store that overnight. The 1500ma panel can put back in a maximum of 1500ma in one hour in strong sunlight directly pointing at it. You need to expect efficiency losses charging batteries and then taking it back out, and of course your panel won't always be directly pointing at the sun, and the sun won't always be shining, but this should help you understand what is feasible. The V5 puts in 300ma in an hour max, and the V9 puts in 900ma an hour max.

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cottonpickers
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Re: Discuss: Solar Charger & battery pack for the Raspberry

Postby cottonpickers » Wed Aug 07, 2013 6:05 am

Velcrow: Shipping is included in the price. Yes, if you can send over paypal I'll get it shipped out -likely tomorrow but Friday at latest. I'm away next week so will get things posted before I head out.

velcrow
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Re: Discuss: Solar Charger & battery pack for the Raspberry

Postby velcrow » Wed Aug 07, 2013 8:23 am

Thanks cottonpicker

I used the link on the previous page and put in the order for £39 but just to confirm its the 1.5amp model for a battery pack (I have the EasyAcc 12000mAh on the way).
Great if you can send out before you go away and let me know if the order is correct ( i.e. do I owe you more for shipping?)

Thanks John

Aegis
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Re: Discuss: Solar Charger & battery pack for the Raspberry

Postby Aegis » Sun Sep 01, 2013 10:20 pm

Hi,

I am interested in this project and would like to ask a few questions.
1. Can i buy a Version 9 with the 1500ma-panel and no battery box, just the two usb? I could'nt find a link to order the for European shipping.
2. Is it possible to buy a batch of 1500ma panels from you with just the usb-connectors? If so, at what price and how many can you deliver?


best regards,
Tim


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