sipp
Posts: 11
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Battery Pack / PSU for Pi ?

Thu Oct 10, 2013 7:03 pm

Hello,

I have what is probably a very simple question for people more experienced than myself. I would like to make a battery power supply for the Pi that I can substitute in for an adapter, and here's the key point: without disconnecting the Pi from power and needing to re-boot.

I think that this is possible simply by wiring the 5V DC supply in parallel with the mains adapter. Is this correct? Also, does anyone know if one could use 4 x AA Ni-MH batteries, or should I use a step-up or step-down converter or 5 x AA with a diode (for 5*1.2V - 0.7V = 5.3V)? This is not for long-term use, more as a occasional measure. Discharging at C, such a pack should be powerful enough at 2.2 or 2.5 W.

Thanks!

sipp
Posts: 11
Joined: Thu Oct 10, 2013 6:49 pm

Re: Battery Pack / PSU for Pi ?

Thu Oct 10, 2013 8:55 pm

OK, apparently a 4 x 1.2V pack works as the Pi and presumably peripherals will operate at 5V +/- 0.5V. Still wondering if I can switch on a battery pack in parallel with the adapter. Do I perhaps need to use a diode to prevent damage to the battery pack or Pi?

sipp
Posts: 11
Joined: Thu Oct 10, 2013 6:49 pm

Re: Battery Pack / PSU for Pi ?

Fri Oct 11, 2013 8:23 pm

Anyone?

Maybe I'll just give it a shot and hope nothing explodes. The Pi has fuses, I think, and the batteries should be able to withstand this, no?

chairsgotoschool
Posts: 77
Joined: Fri Feb 01, 2013 1:34 am

Re: Battery Pack / PSU for Pi ?

Sat Oct 12, 2013 9:07 am

just do a test on something else, an old phone or anything that runs on 5v. its probably not healthy for the battery but shouldn't cause any fires or leaks, if they were fancier like lithium ion which are very sensitive with being charged in general.

ChicagoBob123
Posts: 67
Joined: Fri Aug 30, 2013 1:48 pm

Re: Battery Pack / PSU for Pi ?

Mon Oct 14, 2013 2:04 pm

Sorry for not answering this sooner. I am doing just that. I am powering a pi with 4AA NiMh batteries and using a switch to turn it off and on. Works great. I use another 4AA NiMh batteries to power a 4 port hub. Its all part of my headless wifi terrabyte file/media server. The Pi acts as a DHCP device that I can hook my phone or tablets to and I can serve up movies or music.
through some preliminary tests I can do up to 3 mp4 streams at once.

I stuck the pi hub and the batteries into a small generic box.
In the near future I am looking to upgrade the batteries to a 4000 mAh Li Polymor battery which has multiple 5V USB sources for convenience. I am doing this to avoid taking the batteries in and out all the time and fact is its smaller and lighter than the NiMh
AA's
So you can operate the Pi for hours on AA batteries. Things I have not done is measure the current draw to know how much I am pulling or how long this could lasts on a full charge. The Terrabyte drive may variable based on how many devices I have hooked up but using the USB spec I can estimate 500mah. Not sure how much the WiFi dongle sucks up either.

Bob

chairsgotoschool
Posts: 77
Joined: Fri Feb 01, 2013 1:34 am

Re: Battery Pack / PSU for Pi ?

Tue Oct 15, 2013 2:58 am

cool, is it only 4AA batteries, what type (like rechargable or not) and do you have some sort of circuit for voltage regulations or something or just 4 simple batteries. and whats the voltage and mah on those batteries

also just to make sure. i could make my own cells in a way by connecting 4 AA's in a series muiltiple times so every 4AA's = 1 cell then connect those "cells" in parallel to make it last longer without changing the voltage output (this would come in handy since i dont want to buy a regulator and wire it up) i know it would be big too. thats assuming i need no regulators or anything on the original 4 batteries in the first place

edit also. if its just the pi and a hdd (without external power needed) it should use about 1200mah, the pi uses around 700 and usb supplies 500mah on a normal pc so as long as the hdd doesnt use a y cable or external source it should be around 1200mah together (i know that's assuming the hdd would use all 500mah that a normal usb port supplies, thats because they usually use more.)

ame
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Location: Korea

Re: Battery Pack / PSU for Pi ?

Tue Oct 15, 2013 3:56 am

If you conservatively estimate the Pi + HDD consumes about 1A, and your 4xAA NiMH battery pack has a rating of about 2400mAh, then your system will run for about 2 hours.

Since you have another 4xAA pack powering the hub you might find that the hub also powers the Pi. This would double your operating time to about 4 hours.

sipp
Posts: 11
Joined: Thu Oct 10, 2013 6:49 pm

Re: Battery Pack / PSU for Pi ?

Tue Oct 15, 2013 6:45 pm

Thanks for the responses! But is it possible to wire up the pack such that you can detach it from the mains adapter AND KEEP IT RUNNING on batteries? I think that a mobile solution would be very handy for many people, who usually keep the Pi in one spot running on mains electricity but need to move it temporarily for testing, to use sensors in another place, to take somewhere in the car, to extend wi-fi range, etc.

ChicagoBob123
Posts: 67
Joined: Fri Aug 30, 2013 1:48 pm

Re: Battery Pack / PSU for Pi ?

Tue Oct 15, 2013 8:48 pm

Ahh, you are thinking/moving to my next incarnation of my current battery operated PI.
I am looking at a 4000 mAh 2 USB Charger External Battery Power Bank Pack for iPhone iPad Mobile phone
Its about 26US from China and will take a while to get. That unit should have circuits in it to do just what
you want.
For me I have a small case and will hack the Power Bank case up to it into my Pi case
take power from the 2 USB outputs and feed them into my hub and my PI. Should be able to charge it from
its internal charging circuit while keeping it plugged in.
In my car I can plug it into one of those cigarette lighter USB charging thingies and keep the battery charged
while the PI is on. The batteries should also eliminate the spikes you get from card getting turned off and on.
When I turn the car off I will just disconnect and it should run for hours on battery.
My battery powered terabyte server will at that point be complete for me.

ChicagoBob123
Posts: 67
Joined: Fri Aug 30, 2013 1:48 pm

Re: Battery Pack / PSU for Pi ?

Mon Nov 04, 2013 10:08 pm

Just an update. I have added a 4800mah Li Polymer battery pack to my Portable Pi Server.
It worked great, played about 5 hours of movies from it before it got tired.
It was a bit of a headache to put into my small case but its MUCH lighter and has more power
than 8 AA NiMH batteries and it has its own charging circuit so no I can recharge it any time.
It does have a down side, this batter unit cuts off power when power it applied to it for recharging
which means I will need to add some small diodes to finish.

Does any one know if 20V 1A Schottky diode can be used with a 5V 2Amp supply?
If so i will pick some up from Radio Shack tonight.

ChicagoBob123
Posts: 67
Joined: Fri Aug 30, 2013 1:48 pm

Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 5:41 am

Here are some images of my pi in its case. The case is 6 x 3 x 2 inches deep. Has a charging board 4 port USB and a 4800 mah battery.
It still needs 2 diodes so I can plug in my power directly into the mini USB and charges the battery. The USB ports are powered by the battery. The battery can support the WiFi USB dongle thats inside the case, the pi and the Western Digital hard drive for about 5 hours.

http://s932.photobucket.com/user/chicagobob123/library/

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PiModules
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Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 1:21 pm

Hi,

As I suggest also to other post thread, do not try to invent the wheel. There is a ready product (UPiS) doing what you are asking for, and use exactly the same power supply you have for your RaspberryPi. Just Take it and use it. All other functionality are described here www.pimodules.com

Warmest Regards
Pi Master

ChicagoBob123
Posts: 67
Joined: Fri Aug 30, 2013 1:48 pm

Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 4:25 pm

I looked at your product and wanted some more info that was not clear from the quick review of the site.

To support the Western Digital Drive on start up it exceeded the 500ma limit on the USB power output.
So when you hook up your board is there a way to tap into it so you could grab about 1 to 2 amps at 5V to power
the 4 port USB hub I have hooked up?
One more question does this work with Version A of the raspberry Pi? I did not need the extra stuff for a headless
wifi DHCP samba server.
Thanks.

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PiModules
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Location: Athens -Greece
Contact: Website

Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 4:43 pm

Hi,

I looked at your product and wanted some more info that was not clear from the quick review of the site.
I will try to answer.
To support the Western Digital Drive on start up it exceeded the 500ma limit on the USB power output.
You mean the limit if the RPi USB power output limit?? Please clarify.
So when you hook up your board is there a way to tap into it so you could grab about 1 to 2 amps at 5V to power
the 4 port USB hub I have hooked up?
It is not a standard application. As far I understand you need an extra 5V/1-2A to supply the USB hub when you supply the HDD. So, it is rather not UPS application. You need the 1-2A from the extra 5V output?? M I right ??
One more question does this work with Version A of the raspberry Pi?
For the UPS application UPiS Basic and UPiS Advanced uses powering pins on the P1 connector, it is working. For all other functionalists like RTC or NO Relay etc, RS232, I2C, .. it uses dedicated pins described in the manual, but all are compatible with Version A.
I did not need the extra stuff for a headless
wifi DHCP samba server.
For this WIFI DHCP samba server the UPiS Basic is enought on my opinion
Thanks.

Warmest Regards
Pi Master

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r4049zt
Posts: 113
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Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 5:00 pm

I'd suggest some caution here.
Testing in 2012 a 256Mb Pi with 4x 2000mAh AA batteries (NiMH), it would not boot from 5.2V,5.3V nor 5.5V fully charged. It booted and worked fine for a couple of hours if batteries were at 5.0 V to start and continued to work down to batteries 4.4 V when the mouse conked out, going off when the batteries were a bit more flat.

I've had better sucess with a 1Amp rated DC-DC buck regulator, so that is does not care whether batteries are 6xAA almost flat or 13V car battery. That regulator, set to 5.0V out, can also take input from cheap >6V unregulated rectifier transformer power supplies, though the extra diodes to make a seamless battery or transformer choice would knock 10% off efficiency.

Good luck in your travails and please post here what did not work as well as what did.

FM81
Posts: 518
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Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 5:22 pm

@PiModules: Can you provide a price or a direct link with a price to a site from a distributor?

MfG, FM_81
A: What does the command 'cat /dev/urandom', can you tell me please?
B: Yeah, that's very simple: It feeds your cat with radioactive material!

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PiModules
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Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 5:58 pm

Hi,
I sent units to both distributors, The nettop have listed it already, and the ModMyPI should list it soon. Therefore I give you the link to the nettop, as they have listed already

http://www.nettop.gr/index.php/en/raspb ... E%B5%CF%82

http://www.nettop.gr/index.php/en/raspb ... E%B5%CF%82

however, day to day the ModMyPi will list it. They are preparing the distribution mechanism.
We do not sell to individual customers, we sell only to companies. Individual customers are handled by distributors.

Please notice that we are still writing the manual, and hope that the final version will be released soon, we have already 75 pages. You can download the preliminary version, the final version will be announced soon.

Warmest Regards
Pi Master

ChicagoBob123
Posts: 67
Joined: Fri Aug 30, 2013 1:48 pm

Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 6:41 pm

Hi,
after looking at your documents and looking at the mah of the batteries that are offered I am do not think your device will work for my application. The reasons are several but primarily its power. I am currently using 4800mah Li Polymer battery and wished it was 6000mah. In general I don't think I am reinventing anything and feel pretty good in what I made out of off the shelf parts and some time with a soldering iron. :D

Thanks,
Bob

ChicagoBob123
Posts: 67
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Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 6:47 pm

[quote="r4049zt"]I'd suggest some caution here.
Testing in 2012 a 256Mb Pi with 4x 2000mAh AA batteries (NiMH),

My batteries were rated at 1.2V per battery not sure how you could get more than 4.8V in series.
I didn't have that problem and never had a problem with the 4 batteries using it for several weeks
except for the weight and bulk.
The weight and size change made by switching to Li Polymer a no brainier, plus I can recharge without taking the
batteries out and putting them back in. It cost me < $30 but did take some work to incorporate.

Curiosity has me wondering how you got over 5V ?

FM81
Posts: 518
Joined: Wed Apr 17, 2013 4:33 pm

Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 7:47 pm

Thanks @ PiModules! I'm sure many people will like it!

@ ChicagoBob123:
I think r4049zt is right! These 1,2V are not fix, a full charged has more, if a little bit discharged it goes lower ...
That's why I would see this
I've had better sucess with a 1Amp rated DC-DC buck regulator, so that is does not care whether batteries are 6xAA almost flat or 13V car battery. That regulator, set to 5.0V out, can also take input from cheap >6V unregulated rectifier transformer power supplies, though the extra diodes to make a seamless battery or transformer choice would knock 10% off efficiency.
as the correct way!?

And for safety: I'd also prefer NiMH ...

MfG, FM_81
A: What does the command 'cat /dev/urandom', can you tell me please?
B: Yeah, that's very simple: It feeds your cat with radioactive material!

ChicagoBob123
Posts: 67
Joined: Fri Aug 30, 2013 1:48 pm

Re: Battery Pack / PSU for Pi ?

Wed Nov 06, 2013 9:13 pm

Did not know that about the NiMh battery. I did not experience a problem but did not know they
could kick out more voltage then they are rated for.
Either way the Li Polymer is so much lighter that I would not go back.
I want the power for my application and it would take 8 batteries to come close
to what I get now.
Cheers

sipp
Posts: 11
Joined: Thu Oct 10, 2013 6:49 pm

Re: Battery Pack / PSU for Pi ?

Sun Nov 10, 2013 12:15 am

I was surprised as well, but NiMH batteries are 1.4V when charged, so 4 give 5.6V (in fact, mine measure above 5.7V). This is out of spec. When switching to a pack, you'd want to put in a diode anyway- at 1A an SB320 Schottky diode (rated at 3A) will nicely drop it about 0.3V, which leaves you at 5V +-0.5V for almost the entire discharge cycle of the NiMH's.

sipp
Posts: 11
Joined: Thu Oct 10, 2013 6:49 pm

Re: Battery Pack / PSU for Pi ?

Sun Nov 10, 2013 12:20 am

...but r4049zt's idea is good: a DC buck regulator. Not sure if you can safely wire that in parallel to another power supply if you want to detach the Pi from mains to take it mobile without switching it off (which is possible with the batteries+diode).

Phill Rymer
Posts: 207
Joined: Sun Nov 04, 2012 3:01 am

Re: Battery Pack / PSU for Pi ?

Sun Nov 10, 2013 12:54 am

I use this built in power switch 2 usb out feeds one hell of a run life
http://www.ebay.co.uk/itm/161100064169? ... 1439.l2649

ChicagoBob123
Posts: 67
Joined: Fri Aug 30, 2013 1:48 pm

Re: Battery Pack / PSU for Pi ?

Sun Nov 10, 2013 3:11 pm

Those supplies are great. I own a 12000mah pack. My issues with them are only 2. They are big and heavy. The reason i went with a smaller battery was to make the server light and small.if you look at the pictures i made my pi battery and 4 port hub fit into a 6x3x2 inch case. It might fit into a 1.5 inch high case but it would take special mounting that i don't have.
Anyway if you just want a battery there are several battery packs that work

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