stretch
Posts: 38
Joined: Sat Sep 15, 2012 8:53 am

Solar power advice

Sun Nov 06, 2016 6:20 pm

I'm looking to run a pi3 on solar and I've got hold of 4x12v 17a batteries which are currently wired as 2x24v. I have a 13w 12v/24v solar panel.

I'm wondering what the best configuration to have would be?

1, Use 1x24v setup with voltage drop to 5v.
2, use 1x12v dropped to 5v.
3, Wire 1,2,3 or 4 12v in parellel

Other?

mosespi
Posts: 431
Joined: Mon May 12, 2014 3:35 pm
Location: 34,-118
Contact: Website

Re: Solar power advice

Mon Nov 07, 2016 12:54 am

I wouldn't say there is a 'best' configuration. All depends.. available funds, goals of the project, etc. Some more ramblings from me..

- The higher you go in system voltage, the smaller wires/less voltage drop you will get. 12v and 24v systems are pretty common, higher voltage not so much so. Things like charge controllers start getting expensive when they are not so common. I would stick to 12v or 24v.
- Parallel batteries should generally be of the same type and age, otherwise one may start overcharging. Lots of info about this on the web.
- Two series 12v 17ah batteries is 24v @ 17ah or about 408 watt hours, that is a lot of power for a pi! If your Pi setup takes 3 watts, that is about 5 1/2 days of runtime. You can even just use one 12v battery. I say use one or two and use the other batteries for something else.
- A 13w solar panel will likely not keep a normal Pi running all the time. I had a setup with a 20w panel and it just barely kept up a Pi 2B, camera and wifi setup (about 2.9w) in 24 hour operation. I had less of a reserve using 7ah battery.
- Make sure you use a charge controller. 13w is enough to cook your 17ah batteries without one.

I have a small writeup about my setup, might help you.
http://www.allspectrum.com/mopower/sola ... solar.html

Regards,
-Moses
Power problems? MoPower UPS for the Pi
http://www.allspectrum.com/mopower/

peterlite
Posts: 720
Joined: Sun Apr 17, 2016 4:00 am

Re: Solar power advice

Mon Nov 07, 2016 5:10 am

12v 17ah is more than you need unless you run a screen or some other monster. I looked at 7ah for on project and switched to 9ah to allow for days with a lot of cloud. That leads us to several questions.

Latitude? Sydney gets more sun than Hobart. A Sydney system could run with a smaller solar array and pump out the same power.

What is plugged into the Pi? For some projects, the recommendation is to use one battery for the Pi and separate batteries for whatever is plugged in. A Pi needs accurate power. The other devices might run with cheaper voltage converters. An example is a Pi controlling 12 volt devices.

Two batteries in parallel. One can fail in a way that destroys the other one, producing heat and fumes. Two separate circuits is a safer idea.

stretch
Posts: 38
Joined: Sat Sep 15, 2012 8:53 am

Re: Solar power advice

Mon Nov 07, 2016 9:44 pm

Thanks for the advice the solar panel I have has a charge controller but will look at a bigger panel as ideally looking for 24/7 operation plus the British weather is rubbish. Only need to run the pi and WiFi dongle or ethernet.

IanS
Posts: 158
Joined: Wed Jun 20, 2012 2:51 pm
Location: Southampton, England

Re: Solar power advice

Tue Nov 08, 2016 4:34 pm

England or Wales? Run a reasonable size solar panel.
Scotland? Run it off the mains.
Ireland? Use a waterwheel instead.

(Yes I know only NI is part of Britain.)

peterlite
Posts: 720
Joined: Sun Apr 17, 2016 4:00 am

Re: Solar power advice

Tue Nov 08, 2016 10:07 pm

You live in England. I was there once. London. It was sunny for three days. The Brits said I was there for the whole of summer. :D
Here is another solar discussion from your area: viewtopic.php?f=63&t=150198

homesolar111
Posts: 1
Joined: Mon Nov 13, 2017 6:26 am

Re: Solar power advice

Mon Nov 13, 2017 6:42 am

stretch wrote:
Sun Nov 06, 2016 6:20 pm
I'm looking to run a pi3 on home solar and I've got hold of 4x12v 17a batteries which are currently wired as 2x24v. I have a 13w 12v/24v solar panel.

I'm wondering what the best configuration to have would be?

1, Use 1x24v setup with voltage drop to 5v.
2, use 1x12v dropped to 5v.
3, Wire 1,2,3 or 4 12v in parellel

Other?
Can we connect 12 wires in series combination because i want to lighten my home for festivals. Thank you for sharing this post.

pcmanbob
Posts: 2218
Joined: Fri May 31, 2013 9:28 pm
Location: Mansfield UK

Re: Solar power advice

Mon Nov 13, 2017 11:02 am

Can we connect 12 wires in series combination because i want to lighten my home for festivals. Thank you for sharing this post.
This question makes no sense

what 12 wires ?
were do you want to connect them to ?
what voltages are you talking about using ?
Please only ask questions in the forum I will not answer questions sent to me directly via PM
Remember we want information.......................no information no help

AJB2K3
Posts: 200
Joined: Sun Aug 11, 2013 3:25 pm

Re: Solar power advice

Wed Nov 15, 2017 8:36 pm

IanS wrote:
Tue Nov 08, 2016 4:34 pm
England or Wales? Run a reasonable size solar panel.
Scotland? Run it off the mains.
Ireland? Use a waterwheel instead.

(Yes I know only NI is part of Britain.)
Parallel connected to a wind turbine and your set for life!

(I recognise the joke!)

Don't use a liner power reducer as they waste alot of energy as dangerous heat (I have tried it and even when bolted to a massive lump of metal, they get very hot) use a buck converter.
Back in the old days, we were smarter then the technology.
Nowadays technology makes us look like villages fools in front of the children!

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