rohtua
Posts: 68
Joined: Sat Jul 16, 2016 9:01 am

Recommend a decent power supply

Tue Oct 23, 2018 2:42 pm

Hi everyone,

I just wanted to ask if anyone can recommend a decent power supply for a pi3b+. I have (had :( ) one setup as a CCTV camera but the plug and cable I had were too short to setup neatly out of the way so I obviously thought I need a longer cable here.

I was using a USB plug rated up to 2.4 amps and a 3 meter cable but I was having low power issues where the pi would shut itself off.... It's an issue I seem to keep running into; now with the setup I had the plug I was using was made for charging phones and not to be a power supply so not ideal I know but it was what I had to hand when I set it up. Today I changed the power supply to a 3 amp power supply (not phone charger) and plugged it in. I thought "this should be fine the pi will only use up to 2.5amps and this can give up to 3amps"........ Turns out I was very wrong and my pi died :( :(

So I was hoping someone could recommend a decent power supply that will do the job. I've got a Pi3B+ with the official camera module and no other peripherals. I've been looking on the forums and have come across the usual recommendations for the official supply and I do have a few of them that I tried with the pi first but the issue I always seem to have is there's never enough power!!! The camera pi had the same power issues with an official supply (plus it isn't long enough for what I need) and the pi I borrowed my official supply from is setup as a kodi box under the TV so I can stream media from my NAS which has no peripherals attached often displays the low power lightening bolt in the top right when watching a film!!!!! So I don't seem to have a lot of joy with the power side of things.

If anyone knows of a decent usb plug that would do the job I can get a cable or an actual power supply with about a 5meter cable. I do have some dc barrel to micro usb adapters lying around so I have that option (although that is the option that's fried the current pi with 3amps, so I'm a bit wary now) :(

PhatFil
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Re: Recommend a decent power supply

Tue Oct 23, 2018 3:29 pm

I suspect your longer than usual usb cable may have a significant resistance which is drawing off the power that your pi expects/requires. perhaps its not making a good connection at one or both ends too?

a better quality cable may prove better but in order to contain 4+ wires in a single thin flex the number of strands of metal (not always copper either) in each core is not many so perhaps any 3-5m cable will have some resistance..

i would suggest moving the psu closer to the pi by extending the mains cable or making a diy power cable with heavier guage wires ..

a bit of googeling and a multimeter should allow you to determine the resistance of your cable and therefore work out what power its draining off to let you specify the minimum power requirements for a different psu

Might be worth getting something like a 4-5a psu :) https://www.ebay.co.uk/itm/DC-3-3V-5V-1 ... ctupt=true

edit providing the pi with power from a 3a psu shouldnt be an issue, dc devices draw what they need so having extra capacity is fine.. perhaps you mixed up polarity or missed a solder bridge with your diy cable?

ejolson
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Re: Recommend a decent power supply

Wed Oct 24, 2018 5:59 am

rohtua wrote:
Tue Oct 23, 2018 2:42 pm
If anyone knows of a decent usb plug that would do the job I can get a cable or an actual power supply with about a 5meter cable.
To deliver power over longer distances the usual technique involves running higher voltages on the cable and stepping them down with a 5V regulator at the Pi. An easy way to do this with the 3B+ is via the official power over Ethernet POE hat when it becomes available.

rohtua
Posts: 68
Joined: Sat Jul 16, 2016 9:01 am

Re: Recommend a decent power supply

Sat Jan 26, 2019 11:18 am

Hi guys, I know it's been quite a while since you all posted but I've not been online for a while thanks for all your comments, I hadn't though of the POE solution I'll look into trying that thanks. I did get a longer wall extension which seems to have sorted it for me but it would be nice to have a less bulky solution like the POE. :)

fruitoftheloom
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Re: Recommend a decent power supply

Sat Jan 26, 2019 11:25 am

rohtua wrote:
Sat Jan 26, 2019 11:18 am
Hi guys, I know it's been quite a while since you all posted but I've not been online for a while thanks for all your comments, I hadn't though of the POE solution I'll look into trying that thanks. I did get a longer wall extension which seems to have sorted it for me but it would be nice to have a less bulky solution like the POE. :)

https://www.raspberrypi.org/products/poe-hat/

https://www.raspberrypi.org/blog/introd ... t-poe-hat/
adieu

My other Computer is an Asus CS10 ChromeBit running Chrome Operating System.
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drgeoff
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Re: Recommend a decent power supply

Sat Jan 26, 2019 11:41 am

Bearing in mind that you'll probably need a proper 48 volt PoE PSU/injector in addition to the PoE HAT it does work out quite a bit more expensive than a mains extension cable.

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Imperf3kt
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Re: Recommend a decent power supply

Sat Jan 26, 2019 12:49 pm

Why not use the official power supply plus a short, say 1.5m, extension cable?
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Paul Hutch
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Re: Recommend a decent power supply

Sat Jan 26, 2019 3:32 pm

Imperf3kt wrote:
Sat Jan 26, 2019 12:49 pm
Why not use the official power supply plus a short, say 1.5m, extension cable?
The extra connectors and double the wire length may very well cause too much voltage drop. A better option is to cut out the original wire and solder splice in a larger gauge wire 3m long.

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Imperf3kt
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Re: Recommend a decent power supply

Sat Jan 26, 2019 5:03 pm

Paul Hutch wrote:
Sat Jan 26, 2019 3:32 pm
Imperf3kt wrote:
Sat Jan 26, 2019 12:49 pm
Why not use the official power supply plus a short, say 1.5m, extension cable?
The extra connectors and double the wire length may very well cause too much voltage drop. A better option is to cut out the original wire and solder splice in a larger gauge wire 3m long.
I'm talking about a regular household extension cable, the cable carrying either ~110v or ~220v AC not some kind of USB extension.
Google is ubiquitous - Try it today, it's free!
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rohtua
Posts: 68
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Re: Recommend a decent power supply

Sat Jan 26, 2019 5:22 pm

Imperf3kt wrote: Sat Jan 26, 2019 3:32 pm

Imperf3kt wrote: ↑
Sat Jan 26, 2019 12:49 pm
Why not use the official power supply plus a short, say 1.5m, extension cable?

The extra connectors and double the wire length may very well cause too much voltage drop. A better option is to cut out the original wire and solder splice in a larger gauge wire 3m long.

I'm talking about a regular household extension cable, the cable carrying either ~110v or ~220v AC not some kind of USB extension.
That's kind of what I've ended up with an longer wall extension cable and a shorter power supply to the Pi, not the official one but its a 5v 4amp (or something like that definitely 5v and more than 2 amps anyway, can't get to it atm) DC barrel power supply with a DC to micro usb converter on the end. The POE solution is definitely interesting because it could be less bulky than stretching the extender out; but its working as is now and depending on cost there's probably not much point changing it now unless I'm suddenly desperate for that extra bit of space where I've got the mains extender. :) Thanks for all the help :)

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