nickpalmer789
Posts: 22
Joined: Wed Jul 18, 2012 11:19 pm

Battery power

Sat Aug 11, 2012 11:34 pm

I am trying to get by raspberry pi to run off of battery power. I am new to electronics so I will need a very detailed step by step description. I still need it to connect through the micro USB hub and I need it to run off of commercial batteries that can be replaced. Can someone help me?

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joan
Posts: 15247
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Battery power

Sun Aug 12, 2012 8:24 am

What voltage are the commercial batteries going to supply? If much under/over 5V you'll need a voltage converter..

Will you be using rechargeable batteries? If so will they be recharged in situ or may the Pi have some down time?

nickpalmer789
Posts: 22
Joined: Wed Jul 18, 2012 11:19 pm

Re: Battery power

Sun Aug 12, 2012 3:52 pm

I think that the pi can operate well off of two double A batteries. That is what they said on the rpi website. I also think that I will use non rechargeable batteries. And I would like it to have an on off switch. How would you do something lime that?

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rpdom
Posts: 17958
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Battery power

Sun Aug 12, 2012 4:03 pm

Two AA batteries would produce 3v, not the 5v that the Pi needs.

Four AA NiCD/MiMH rechargeable batteries will give about 4.8v, which is borderline for the Pi (min 4.75v for proper operation).

Your best bet is to have batteries that supply at least 7v and use a dc-dc converter to drop that to between 5 and 5.25v.

I have briefly tested my Pi (and USB disk) with a couple of Lithium Ion cells from an old laptop battery (2 x 3.6v) and a 7805 1.5A linear voltage regulator. It worked for a short while, but the batteries needed charging at the time. This isn't a very effieceint way of doing things, just I had all the parts to hand.

chrisborrill
Posts: 7
Joined: Sat Jul 21, 2012 6:12 am

Re: Battery power

Mon Aug 13, 2012 6:50 am

I have bought one of these which a plan to power off a 3 cell lipo, but it has not arrived yet:

http://www.ebay.com/itm/DC-7V-24V-to-5V ... 27ca182ff3

Larsey
Posts: 39
Joined: Fri Jun 29, 2012 5:27 pm

Re: Battery power

Mon Aug 13, 2012 7:21 am

As I understands it the Pi needs 5v, and atleast 750 mA.

So I shopped
- 4 x Anseman batteries http://uk.rs-online.com/web/p/aa-rechar ... s/6708741/
- 1x Holder http://uk.rs-online.com/web/p/battery-h ... s/0594628/

Tested it with a multimeter and somewhat charged it gives me ~5.1V and lasts almost 3 hours. Works great. But you also need a micro usb-b connector, I just chopped and soldered one I had around.

Ravenous
Posts: 1956
Joined: Fri Feb 24, 2012 1:01 pm
Location: UK

Re: Battery power

Mon Aug 13, 2012 8:42 am

You really need 5v stable, so need a good 5 volt regulator. Preferably a 5V switchng voltage regulator for efficiency

Many, many have asked this on the forums, less have made it work. Here's a good one (though you don't need the solar panel):

http://www.raspberrypi.org/phpBB3/viewt ... 63&t=13901

nickpalmer789
Posts: 22
Joined: Wed Jul 18, 2012 11:19 pm

Re: Battery power

Mon Aug 13, 2012 11:44 am

Thanks for the help. Although I am a noob at electronics in the hardware sense (I am working on that) I still need some more in depth instructions on how to do this. Can anyone help me out by pointing me to a tutorial or something? Once again thanks for the help that you have given so far. :D

Ravenous
Posts: 1956
Joined: Fri Feb 24, 2012 1:01 pm
Location: UK

Re: Battery power

Mon Aug 13, 2012 12:34 pm

Another forum post here, including links to possible regulators and it discusses some more:

http://www.raspberrypi.org/phpBB3/viewt ... =63&t=5999

Here's a datasheet for a regulator I've used (not for the raspi though, as this one is only 500mA - but 1A or better versions are available) (this one costs around six quid, from Rapid):

http://www.rapidonline.com/pdf/84-2551.pdf

There are LOTS of threads on the forum where people have asked this question, though finding a definitive one where links are provided to good regulators is hard! So I'm trying to answer this off the top of my dodgy head.

By the way the whole point of the switching reg is: the raspi needs 5V at 700 milliamps (that's the max specification) - if you use say 8 AA rechargeables in series at around 9.6V, a perfect 100% efficient regulator will draw under 400mA.

I have never run a raspi off batteries (I'll start with the model A, which may use much less power). I've used the unit I linked above to run various small things off a domestic "robot" thing, connected to 12V worth of old batteries. Seems to work OK using the simple circuit in that datasheet. (Make sure there aren't any shorts, and remember not to let rechargeable batteries drain too much - though they're entirely separate discussions.)

EDIT: Also see the wiki at:

http://elinux.org/RPi_5V_PSU_construction

...as well as less efficient 7805-style regulator, there's a link to another switched type right at the bottom.

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ripzay
Posts: 28
Joined: Thu Jul 19, 2012 9:32 am

Re: Battery power

Mon Aug 13, 2012 1:32 pm

I have been looking into this problem myself and have come across this IC....

http://uk.farnell.com/analog-devices/ad ... dp/2070675

Not cheap but seems to do exactly what we require (though unfortunately in a hard-to-solder package) for a single High Amp Hour 3.7v Li-Po cell,

As far as I can tell, all that would be needed above and beyond this is a simple DC-DC converter to take the ~3.7v from the LiPo output to 5v to supply the Pi

Or am i completely off the mark - i've never had to deal with power / battery management before ?

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climberhunt
Posts: 5
Joined: Wed Aug 15, 2012 12:32 pm

Re: Battery power

Thu Aug 16, 2012 9:16 am

Working battery solution here: http://davidhunt.ie/?p=2641
Uses a camera battery at 7.2V, 1800mAh, car phone charger (7-12v - 5V) all nicely wrapped up in a camera battery grip.

catmaker
Posts: 50
Joined: Thu May 24, 2012 8:32 am

Re: Battery power

Thu Aug 16, 2012 4:17 pm

Maybe you'd like to try the Raspy Juice Exp Board ?
http://www.raspberrypi.org/phpBB3/viewt ... 59&t=14654

It's a compact PCB that piggybacks onto the Pi and contains an efficient buck regulator that accepts 6-23V voltage input. It supplies the Pi through the GPIO header with a regulated +5V and can be powered by batteries. (You can also tap off more +5V outputs from its servo ports to supply other stuff like USB, HDD, etc).

Maille
Posts: 8
Joined: Mon Nov 26, 2012 2:36 pm

Re: Battery power

Mon Nov 26, 2012 11:08 pm

Hope to test my 12000mAh battery pack that outputs at 5V and see how long the pi lasts.
http://www.amazon.co.uk/dp/B008YRG5JQ/r ... 05151_dp_1
Also hope to re-jig the the battery output to enable it to power a pico that currently runs for about and hour from its 3.7V 1410mAh battery (which runs & charges by outputting 12V 2A)
.........

Maille
Posts: 8
Joined: Mon Nov 26, 2012 2:36 pm

Re: Battery power

Sat Dec 29, 2012 2:47 pm

I managed around 14hrs from the 12000mAh battery pack on rasbian of that it was mostly idle but had a good solid 2hrs of 720p and mayb another 2hrs of xbmc library syncing

adamtlee87
Posts: 4
Joined: Mon Jan 07, 2013 7:10 am

Re: Battery power

Mon Jan 07, 2013 7:22 am

@maille
I too am new to electronics and was wondering if the battery pack that you linked would be able to also charge a small screen such as this one. http://www.amazon.com/3-5-Inch-TFT-Moni ... Z3D163V767 if I soldered the power connector on the monitor to a usb connection?

Metz
Posts: 37
Joined: Mon Nov 28, 2011 3:38 pm

Re: Battery power

Mon Jan 07, 2013 11:29 am

I've discovered that the poundshop is your friend in this instance :) I'm sure someone will tell me its a bad idea, but I bought an 'emergency phone charger' for the princely sum of £1....put four AAA batteries in it (20 for....you guessed it....£1). It has a micro-USB connector on it...and I just plugged it straight in to the Pi. Booted first time, no problem at all :) I left it running for about 20 mins before I needed the Pi back :) Tonight, I'll set it running indefinitely...see how long it lasts with a USB Wifi Dongle in there ;)

Maille
Posts: 8
Joined: Mon Nov 26, 2012 2:36 pm

Re: Battery power

Mon Jan 07, 2013 7:24 pm

adamtlee87 wrote:@maille
I too am new to electronics and was wondering if the battery pack that you linked would be able to also charge a small screen such as this one. http://www.amazon.com/3-5-Inch-TFT-Moni ... Z3D163V767 if I soldered the power connector on the monitor to a usb connection?
I don't think so; "Power: <=3W Power supply: DC 12V" you'd have to get a circuit in there to boost up to 12V and I don't think the power pack will give 3W anyway.
Luckly there is a solution, a much more expensive solution;
http://gadgets.ndtv.com/laptops/news/hp ... 013-314369

If your looking you could just get a 12V car battery or look for a TFT screen that will take 2Amps @ 5V

Also I have a Pico PK301+ and Optoma have assured me that I can buy a usb lead to power it for €10

noob
Posts: 222
Joined: Sat Dec 08, 2012 3:58 pm

Re: Battery power

Tue Jan 08, 2013 7:00 pm

i had got a sun charger with build in spare battery as christmas gift from my fathers job and it ran well, the only problem was that it was empty in like 20 minutes

Maille
Posts: 8
Joined: Mon Nov 26, 2012 2:36 pm

Re: Battery power

Tue Jan 08, 2013 9:02 pm

Solar chargers a fine but generally they won't draw 10W, realistically I'd need an 80W panel to run the pi here in Ireland.

mikerr
Posts: 2826
Joined: Thu Jan 12, 2012 12:46 pm
Location: UK
Contact: Website

Re: Battery power

Mon Feb 11, 2013 11:00 am

nickpalmer789 wrote:I think that the pi can operate well off of two double A batteries. That is what they said on the rpi website. I also think that I will use non rechargeable batteries. And I would like it to have an on off switch. How would you do something lime that?
Pi needs around 5v which is much more than the 3V 2x AAs provide - but you can get "emergency phone charger" devices very cheaply which come with a DC-DC convertor to boost the voltage to 5V and also provide a usb socket:

Image
http://dx.com/p/2-aa-powered-usb-emerge ... g-3g-30251

Cost just £1 from ebay :shock: :)

Pi booted up fine with its usb wifi dongle - I'll recharge my 2000mah hybrios and have it send an email a minute to see how long you get from a full charge.
(doing this just for fun - those 12000mAh packs are a better real solution as they give 12+ hours of use)
Last edited by mikerr on Fri Apr 19, 2013 10:00 pm, edited 1 time in total.
Android app - Raspi Card Imager - download and image SD cards - No PC required !

Gustavo_Murta
Posts: 24
Joined: Thu Dec 20, 2012 10:04 am
Location: Brasil

Re: Battery power

Mon Feb 11, 2013 11:23 am

Low drop out Regulators :

Use low drop out regulators to convert battery voltage to 5V USB power connector. The output current can be 500mA to up 3A, depending of the regulator.
These regulators are frequently used in cars. Some manufacturers poduce it like Infineon, Linear, Texas, etc.
Some examples:

IN = 6V out = 5V current 1,5A => LT1086
http://www.linear.com/product/LT1086

IN = 5,5V, out = 5V current 3A => LT1529
http://www.linear.com/product/LT1529

IN = 6V out = 5V current 1A => LM2940
http://www.ti.com/lit/ds/symlink/lm2940-n.pdf

Raspberry Pi use low dropout regulators (chinese) to achieve 3,3V and 1,8V from 5V power source.

5V to 3,3V LDO regulator (REG 2) : SE8117T33

5V to 1,8V LDO regulator (REG 1) : SE8117T18

http://pdf.dzsc.com/SE8/SE8117.pdf

Gustavo Murta (Brazil)

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