CharlesGodwin
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Location: Ottawa Canada

Powering the Pi

Thu Aug 23, 2012 11:16 am

I plan to use my Pi to monitor my remote cottage's solar power system and other sensors. I will use the Pi as a web server to allow me to remotely access the data.

My problem is powering all this equipment. I will have the following:
  • Cell phone amplifier as I am at least 13km from the nearest cell tower
    Cellular broadband router
    Network switch for various monitored devices with Ethernet connectivity (router has only one ethernet port)
    Raspberry Pi
All of these other devices are rated for 6VDC and the Pi is rated for 5VDC. I will be using my solar system batteries as my power source. It is 24VDC and DC/DC converters are available.

My question is:
Can I operate the RPi from a 6VDC supply?

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Burngate
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Re: Powering the Pi

Thu Aug 23, 2012 3:06 pm

Not directly, no - 6V is too much. You might get away with it for a shortwhile, or maybe not - there's an overvoltage protection diode that shouldn't trigger below 6.4V, but the Soc takes in 5V, and won't be rated for 6V. Also any USB devices you attach might complain.

How do you intend powering all the rest? You may find you can get 5V out of whatever PSU you are using.

Alternatively, if the solar power system is producing 230V, you could use an ordinary wall-wart.

CharlesGodwin
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Re: Powering the Pi

Thu Aug 23, 2012 4:33 pm

Thanks.

The rest will be powered from the 6VDC regulator. I was hoping to be simplistic with one power supply. but if I must I can use one for 6VDC and one for 5VDC.

I considered using my 120VAC (Canadian you know) but I prefer to turn off the AC inverter when I'm not in residence. The inverter has only 90-95% efficiency and I'd rather not run it. Also, as I will be running at low temperatures in the winter I planned to put the "electronics" in an insulated box and the inverter won't fit ;)

sjfaustino
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Re: Powering the Pi

Thu Aug 23, 2012 4:41 pm

I'm using one of these and it works beautifully :)

CharlesGodwin
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Re: Powering the Pi

Thu Aug 23, 2012 5:01 pm

what do you mean by "one of these"?

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mahjongg
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Re: Powering the Pi

Thu Aug 23, 2012 5:03 pm

Just use a $1,50 low drop fixed 5V regulator, such as the L4940V5 mounted on a small heatsink (dissipation will be only a half watt though, so just a very small heatsink will suffice) Add a few 1uF elcos, on the input and output (to GND) and you are ready, 6Volt in stable 5Volt out, and more than enough current for a PI (as long as it can draw that current from the 6V that is) it will work with as low as 5.5Volt input.

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Burngate
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Re: Powering the Pi

Fri Aug 24, 2012 8:10 am

CharlesGodwin wrote:... 120VAC (Canadian you know) ... ;)
Sorry for the parochialism ;)
Yes, if you've already produced the 6V it would have been better if you could have used it, but an amp at 5V shouldn't need anything big from the same source.

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RaTTuS
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Re: Powering the Pi

Fri Aug 24, 2012 8:21 am

CharlesGodwin wrote:what do you mean by "one of these"?
there is a link in the post
see
http://www.ebay.com/itm/LM2596-DC-Step- ... 788wt_1397
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX
Covfefe

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campi
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Re: Powering the Pi

Fri Aug 24, 2012 11:10 am

RaTTuS wrote:
CharlesGodwin wrote:what do you mean by "one of these"?
there is a link in the post
see
http://www.ebay.com/itm/LM2596-DC-Step- ... 788wt_1397
That is the DC/DC converter that I am using in a solar installation in my motorhome, and it works perfectly. The Pi loves it!

campi.

CharlesGodwin
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Location: Ottawa Canada

Re: Powering the Pi

Fri Aug 24, 2012 11:36 am

This looks like an excellent solution. Thank you RaTTuS and campi.

Now all I need is to wire it to a micro USB connector. Or.. perhaps I'll just feed the 5VDC to a powered USB hub and run the Pi and any USB peripherals I need from that.

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RaTTuS
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Re: Powering the Pi

Fri Aug 24, 2012 11:44 am

I hate to take credit where it's not due but the item came from the post of
sjfaustino
:-
Re: Powering the Pi
by sjfaustino » 23 Aug 2012 17:41

I'm using one of these and it works beautifully
the these bit was a link to the item i posted - but as I'm on prosilver I can see the link ;-p
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX
Covfefe

pygmy_giant
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Re: Powering the Pi

Fri Aug 24, 2012 1:59 pm

don't care who takes the credit - i'm buying two!

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alexeames
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Re: Powering the Pi

Mon Aug 27, 2012 6:31 pm

pygmy_giant wrote:don't care who takes the credit - i'm buying two!
I've already got 6 with 10 more on the way. :D (Same thing, same PCB, From different vendor) They're really pretty good. No idea on longevity, but converting 12V to 5V they are 85% efficient.
Alex Eames RasPi.TV, RasP.iO

CharlesGodwin
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Location: Ottawa Canada

Re: Powering the Pi

Mon Aug 27, 2012 6:35 pm

Thanks for the encouragement. I have 5 on their way.

I plan 24VDC (22-30) to 6VDC and 5VDC (several units). I'll report to this thread my efficiency results.

sjfaustino
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Re: Powering the Pi

Mon Sep 10, 2012 7:58 am

RaTTuS wrote:
CharlesGodwin wrote:what do you mean by "one of these"?
there is a link in the post
see
http://www.ebay.com/itm/LM2596-DC-Step- ... 788wt_1397
The admins really should edit the default forum theme to show links in a diferent color, otherwise there's no sense in going to the trouble of "beautifying" links!

BTW, I'm using one of these converters with a 12V 2.5A power supply from a external USB HDD, soldered a 1 ohm 0.25w resistor on F1 and F2 and can use a 3G pen going full speed and a wireless pen plus the ethernet and HDMI at the same time, no need for powered hub :)

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