eNORm
Posts: 21
Joined: Tue May 29, 2012 3:04 pm
Location: Norway, Oslo

Professional Power Supply

Wed Nov 26, 2014 1:24 pm

Can some of you recomend me a professional power supply for 4 RPI'es? I need a power supply that is 100% stable, handles cold weather and cutting of power.
Expology.no

drgeoff
Posts: 10245
Joined: Wed Jan 25, 2012 6:39 pm

Re: Professional Power Supply

Wed Nov 26, 2014 3:29 pm

eNORm wrote:Can some of you recomend me a professional power supply for 4 RPI'es? I need a power supply that is 100% stable, handles cold weather and cutting of power.
You need to explain better what you mean by "handles .. cutting of power".

eNORm
Posts: 21
Joined: Tue May 29, 2012 3:04 pm
Location: Norway, Oslo

Re: Professional Power Supply

Wed Nov 26, 2014 5:55 pm

I think I found it.

English Link
https://www.elfa.se/elfa3~eu_en/elfa/in ... =10-517-52

Should be able to drive 4 PIes.
Expology.no

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davidcoton
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Location: Cambridge, UK

Re: Professional Power Supply

Wed Nov 26, 2014 7:06 pm

No mention of "handles ... cutting of power.", but otherwise it should do the job. Bit of overkill, perhaps, if you don't need the other voltage rails.
Signature retired

boyoh
Posts: 1402
Joined: Fri Nov 23, 2012 3:30 pm
Location: Selby. North Yorkshire .UK

Re: Professional Power Supply

Wed Nov 26, 2014 11:22 pm

eNORm wrote:I think I found it.

English Link
https://www.elfa.se/elfa3~eu_en/elfa/in ... =10-517-52

Should be able to drive 4 PIes.


The shown power supply will supply all the
voltage and current you will need, But the
10amp out put is to high to give protection
to the 4 individual Pi /s I suggest you use
some form of over current protection on the
power in/put. to the 4 Pis

1. Electronic 1.5 / 2amp adjustable ( x 4 )
2. 1.5 / 2amp quick blow in-line glass fuse ( x 4 )

100% Stable ? Debatable
BoyOh ( Selby, North Yorkshire.UK)
Some Times Right Some Times Wrong

eNORm
Posts: 21
Joined: Tue May 29, 2012 3:04 pm
Location: Norway, Oslo

Re: Professional Power Supply

Thu Nov 27, 2014 9:54 am

davidcoton wrote:No mention of "handles ... cutting of power.", but otherwise it should do the job. Bit of overkill, perhaps, if you don't need the other voltage rails.
The PIes are inside a container, that will be transported around Norway for the Red Cross. When the container comes to a new place, they plug in the power and the PIes boot up. When they're done, they just cut the power to the cointainer.

Hope this is more spesific.
Expology.no

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RaTTuS
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Re: Professional Power Supply

Thu Nov 27, 2014 9:58 am

well if you want to survive sudden power fails then you need a battery backed shutdown system
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WARNING - some parts of this post may be erroneous YMMV

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boyoh
Posts: 1402
Joined: Fri Nov 23, 2012 3:30 pm
Location: Selby. North Yorkshire .UK

Re: Professional Power Supply

Thu Nov 27, 2014 3:00 pm

eNORm wrote:
davidcoton wrote:No mention of "handles ... cutting of power.", but otherwise it should do the job. Bit of overkill, perhaps, if you don't need the other voltage rails.
The PIes are inside a container, that will be transported around Norway for the Red Cross. When the container comes to a new place, they plug in the power and the PIes boot up. When they're done, they just cut the power to the cointainer.

Hope this is more spesific.

I'm just a bit curious, what are the Red Cross
using the Pis for.. Have you built a project for
them to display something, or what.
While at different locations , will you have
any control over them, The more the Forum
know the more they can help.
Excuse me for being nosy, put i'm curious
Regards BoyOh
BoyOh ( Selby, North Yorkshire.UK)
Some Times Right Some Times Wrong

User avatar
davidcoton
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Location: Cambridge, UK

Re: Professional Power Supply

Thu Nov 27, 2014 6:43 pm

RaTTuS wrote:well if you want to survive sudden power fails then you need a battery backed shutdown system
To fill in a bit more (which you may or may not already know) the problem with sudden power loss is that you don't know what the Pis were doing, and if they were writing to the SDCard or other storage, the image might end up corrupted. Then the Pis may not restart, or stored data may be lost. If the Pis can be properly shut down before power is removed, there should be no problem. So if the system must survive sudden (unexpected) removal of power, you need a small battery backup and a circuit (and software) to tell the Pis to shutdown when the main supply fails.
Signature retired

eNORm
Posts: 21
Joined: Tue May 29, 2012 3:04 pm
Location: Norway, Oslo

Re: Professional Power Supply

Sat Nov 29, 2014 10:40 am

boyoh wrote:
eNORm wrote:
davidcoton wrote:No mention of "handles ... cutting of power.", but otherwise it should do the job. Bit of overkill, perhaps, if you don't need the other voltage rails.
The PIes are inside a container, that will be transported around Norway for the Red Cross. When the container comes to a new place, they plug in the power and the PIes boot up. When they're done, they just cut the power to the cointainer.

Hope this is more spesific.

I'm just a bit curious, what are the Red Cross
using the Pis for.. Have you built a project for
them to display something, or what.
While at different locations , will you have
any control over them, The more the Forum
know the more they can help.
Excuse me for being nosy, put i'm curious
Regards BoyOh
It's a very simple setup. You push a button and a sound file is played. Nothing fancy. I'll have some remote control over them, since the container is connected to the Internet.
Expology.no

eNORm
Posts: 21
Joined: Tue May 29, 2012 3:04 pm
Location: Norway, Oslo

Re: Professional Power Supply

Sat Nov 29, 2014 10:43 am

davidcoton wrote:
RaTTuS wrote:well if you want to survive sudden power fails then you need a battery backed shutdown system
To fill in a bit more (which you may or may not already know) the problem with sudden power loss is that you don't know what the Pis were doing, and if they were writing to the SDCard or other storage, the image might end up corrupted. Then the Pis may not restart, or stored data may be lost. If the Pis can be properly shut down before power is removed, there should be no problem. So if the system must survive sudden (unexpected) removal of power, you need a small battery backup and a circuit (and software) to tell the Pis to shutdown when the main supply fails.
I know about this, it's the same problem with any other computer. I got the root filesystem on a USB stick, so hopefully that will make it a bit more robust. Fsck should take care of potential corruptions.

I know it's not optimal, but that's how things got done in the end.
Expology.no

boyoh
Posts: 1402
Joined: Fri Nov 23, 2012 3:30 pm
Location: Selby. North Yorkshire .UK

Re: Professional Power Supply

Sat Nov 29, 2014 2:43 pm

boyoh wrote:
eNORm wrote:
davidcoton wrote:No mention of "handles ... cutting of power.", but otherwise it should do the job. Bit of overkill, perhaps, if you don't need the other voltage rails.
The PIes are inside a container, that will be transported around Norway for the Red Cross. When the container comes to a new place, they plug in the power and the PIes boot up. When they're done, they just cut the power to the cointainer.

Hope this is more spesific.

I'm just a bit curious, what are the Red Cross
using the Pis for.. Have you built a project for
them to display something, or what.
While at different locations , will you have
any control over them, The more the Forum
know the more they can help.
Excuse me for being nosy, put i'm curious
Regards BoyOh

Thank you for your reply to my curiosity
Hope your project works ok on arrival
at the Red Cross, Hope you have good
internet connection. I'm lucky.I can see
the telephone exchange from my house
Broadband ( wire) 17meg
Regards BoyOh
BoyOh ( Selby, North Yorkshire.UK)
Some Times Right Some Times Wrong

BMS Doug
Posts: 3824
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Professional Power Supply

Tue Dec 02, 2014 9:11 am

eNORm wrote:
RaTTuS wrote:well if you want to survive sudden power fails then you need a battery backed shutdown system
davidcoton wrote: To fill in a bit more (which you may or may not already know) the problem with sudden power loss is that you don't know what the Pis were doing, and if they were writing to the SDCard or other storage, the image might end up corrupted. Then the Pis may not restart, or stored data may be lost. If the Pis can be properly shut down before power is removed, there should be no problem. So if the system must survive sudden (unexpected) removal of power, you need a small battery backup and a circuit (and software) to tell the Pis to shutdown when the main supply fails.
I know about this, it's the same problem with any other computer. I got the root filesystem on a USB stick, so hopefully that will make it a bit more robust. Fsck should take care of potential corruptions.

I know it's not optimal, but that's how things got done in the end.
The USB sticks are just as susceptible to corruption as the micro SD cards, I would add a small battery and some kind of power monitor so that you can have a safe shutdown.
eNORm wrote:It's a very simple setup. You push a button and a sound file is played. Nothing fancy. I'll have some remote control over them, since the container is connected to the Internet.
As I understand it the main risk of corruption is from power removal during a write to memory, as your project seems to be read only you might be relatively safe.
Doug.
Building Management Systems Engineer.

RobinGreig
Posts: 15
Joined: Sat Oct 27, 2012 2:40 am
Location: Calgary, Alberta, Canada

Re: Professional Power Supply

Wed Dec 17, 2014 9:47 pm

For most of my Raspberry Pi circuits, I use a Wall Adapter and 6x1.5V Batteries as my backup.
I've got my circuit posted at www.robingreig.ca

Essentially I have my wall adapter feeding my 5V power supply through a diode, and my batteries feeding the power supply through a diode as well. Since the power supply is usually 3V higher, the battery diode stays reverse biased and there is no draw from the batteries. If the utility power fails, then as the voltage to the power supply decreases, the battery diode will become forward biased and the batteries will provide the voltage to the power supply.

This is great for situations where I lose power for a short period of time and it is restored.

I am investigating the PIC solutions on this forum for when power is not restored soon enough and the Pi is in danger of an uncontrolled shutdown.

Thanks,
Robin
www.robingreig.ca
www.robingreig.ca
Arduino + Raspi + Amateur Radio enthusiast since 2012
VE6RBN Canadian Amateur Radio Callsign

drgeoff
Posts: 10245
Joined: Wed Jan 25, 2012 6:39 pm

Re: Professional Power Supply

Fri Dec 19, 2014 1:39 pm

RobinGreig wrote:For most of my Raspberry Pi circuits, I use a Wall Adapter and 6x1.5V Batteries as my backup.
I've got my circuit posted at http://www.robingreig.ca

Essentially I have my wall adapter feeding my 5V power supply through a diode, and my batteries feeding the power supply through a diode as well. Since the power supply is usually 3V higher, the battery diode stays reverse biased and there is no draw from the batteries. If the utility power fails, then as the voltage to the power supply decreases, the battery diode will become forward biased and the batteries will provide the voltage to the power supply.

This is great for situations where I lose power for a short period of time and it is restored.

I am investigating the PIC solutions on this forum for when power is not restored soon enough and the Pi is in danger of an uncontrolled shutdown.

Thanks,
Robin
http://www.robingreig.ca
A further refinement would be to use rechargeable cells and add a suitable value resistor in parallel with the battery diode to trickle charge it.

suicidal_orange
Posts: 217
Joined: Sun Mar 16, 2014 10:56 am

Re: Professional Power Supply

Sun Dec 21, 2014 2:49 pm

If you're not planning to save anything on these Pis then you could run them on Core Linux which boots to a RAM disk. Once booted the SD card (or other root filesystem) is unmounted so there no risk of corruption unless power is pulled during boot.

If you do need to save something (maybe to update the "sound"?) you can always mount the partition(s), save the files, then unmount them.

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