mbr
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Power supply for multiple Pi4's needed. Advice?

Mon Nov 25, 2019 2:08 pm

Hi folks,

I would like to have some Pi4 machines setup and running, and I would like to have "one ring (aka power supply) to rule them all".
So it should provide multiple USB sockets with 5V, 3A each.

For my older Pi3 / 3B+, I used a 6x 5V-2,4A supply, like e.g. this one:
https://www.amazon.de/gp/product/B01DZQ ... UTF8&psc=1

Is there somewhere a device like that, but with 3A outputs?

Regards
Mattias

trejan
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Re: Power supply for multiple Pi4's needed. Advice?

Mon Nov 25, 2019 4:15 pm

You only need 3A if you're using the full 1.2A of USB peripherals. If you keep USB peripherals < 500mA then a 2.5A PSU is fine.

bjtheone
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Re: Power supply for multiple Pi4's needed. Advice?

Mon Nov 25, 2019 7:00 pm

Most of those (like the one OP listed - 12 A max / 6 = 2 A max if all ports are loaded) do not supply the max per port current simultaneous on all ports. Others do not regulate particularly well when at max current. Does not mean it will not work, since it is unlikely all your Pi's are going to be anywhere near max current at the same time, but it is something to consider.

A better solution may be to buy an actual power supply that will supply the required current, with good regulation.

dustnbone
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Re: Power supply for multiple Pi4's needed. Advice?

Mon Nov 25, 2019 7:15 pm

Just use a proper 5V industrial supply like this one

https://www.sparkfun.com/products/14098

Then you don't have to worry about individual ports having enough power, as long as your total load for all things connected is under 20A.

There is a small amount of voltage adjustment so you can bump it up to 5.1V or whatever to keep them happy.

Moonmarch
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Re: Power supply for multiple Pi4's needed. Advice?

Mon Nov 25, 2019 11:46 pm

I see USB power adapters that can charge the Apple MacBook using this USB-C intelligent charge system which we all know is not compatible with the RPI computer the adapter is rated at 60W, 5v 3a compatible, and the adapter includes 2 USB-C ports here is the link to the product:

Anker 60W 2-Port USB C Charger, PowerPort Atom PD 2 [GAN Tech] Compact Foldable Wall Charger, Power Delivery for MacBook Pro/Air, iPad Pro, iPhone 11 / Pro/Max/XR/XS/X, Pixel, Galaxy, and More
https://www.amazon.com/Anker-AK-A202912 ... JEMTJY83JG

The other USB power strips available on Amazon appear to be 5v 2.4a I don't know if the power strip will power all of the RPI computers simultaneously you should be able to purchase similar USB power strips at the local electronics store which means you don't need to purchase the power strip from online stores.

drllama
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Re: Power supply for multiple Pi4's needed. Advice?

Tue Nov 26, 2019 2:53 am

I use a 10 port supply: https://www.amazon.com/Alxum-Charging-O ... B01NBTNEO0 currently with 7 RPi4 connected (three more to flesh out my bramble soon), and they're doing fine.

It's worth noting that the only things plugged into the RPIs are a small fan and a USB flash stick.

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rin67630
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Re: Power supply for multiple Pi4's needed. Advice?

Tue Nov 26, 2019 3:05 am

dustnbone wrote:
Mon Nov 25, 2019 7:15 pm
Just use a proper 5V industrial supply like this one
It is a pretty bad idea to power many drains with a single high current source, without properly fusing each output.

plugwash
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Re: Power supply for multiple Pi4's needed. Advice?

Tue Nov 26, 2019 10:38 am

Moonmarch wrote:
Mon Nov 25, 2019 11:46 pm
I see USB power adapters that can charge the Apple MacBook using this USB-C intelligent charge system which we all know is not compatible with the RPI computer
PD chargers in general are fine, what can be problematic are electronically marked USB-C cables.
the adapter is rated at 60W, 5v 3a compatible, and the adapter includes 2 USB-C ports here is the link to the product:

Anker 60W 2-Port USB C Charger, PowerPort Atom PD 2 [GAN Tech] Compact Foldable Wall Charger, Power Delivery for MacBook Pro/Air, iPad Pro, iPhone 11 / Pro/Max/XR/XS/X, Pixel, Galaxy, and More
https://www.amazon.com/Anker-AK-A202912 ... JEMTJY83JG
What is not 100% clear from the specs I can find is if it can do 5V 3A from both ports at the same time.

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Imperf3kt
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Re: Power supply for multiple Pi4's needed. Advice?

Tue Nov 26, 2019 9:08 pm

plugwash wrote:
Tue Nov 26, 2019 10:38 am
Moonmarch wrote:
Mon Nov 25, 2019 11:46 pm
I see USB power adapters that can charge the Apple MacBook using this USB-C intelligent charge system which we all know is not compatible with the RPI computer
PD chargers in general are fine, what can be problematic are electronically marked USB-C cables.
the adapter is rated at 60W, 5v 3a compatible, and the adapter includes 2 USB-C ports here is the link to the product:

Anker 60W 2-Port USB C Charger, PowerPort Atom PD 2 [GAN Tech] Compact Foldable Wall Charger, Power Delivery for MacBook Pro/Air, iPad Pro, iPhone 11 / Pro/Max/XR/XS/X, Pixel, Galaxy, and More
https://www.amazon.com/Anker-AK-A202912 ... JEMTJY83JG
What is not 100% clear from the specs I can find is if it can do 5V 3A from both ports at the same time.
60w at 5v is 12A
I would take a guess and say it probably can.
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davidcoton
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Re: Power supply for multiple Pi4's needed. Advice?

Tue Nov 26, 2019 9:11 pm

Imperf3kt wrote:
Tue Nov 26, 2019 9:08 pm
plugwash wrote:
Tue Nov 26, 2019 10:38 am
What is not 100% clear from the specs I can find is if it can do 5V 3A from both ports at the same time.
60w at 5v is 12A
I would take a guess and say it probably can.
Poor guess. Many PD PSUs can only supply the full rated power at higher voltages, the current at 5V is just too high.
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Imperf3kt
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Re: Power supply for multiple Pi4's needed. Advice?

Tue Nov 26, 2019 9:17 pm

There's also the Pirl charger, tested to be capable of 2.7A per port simultaneously (rated for 2.5)

https://youtu.be/J58RLAKeIps
davidcoton wrote:
Tue Nov 26, 2019 9:11 pm
Poor guess. Many PD PSUs can only supply the full rated power at higher voltages, the current at 5V is just too high.
I don't see why. 5v 3A is listed in usb-c spec.
The Anker power supplies have all had very high regard here from dozens of forum users.
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davidcoton
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Re: Power supply for multiple Pi4's needed. Advice?

Tue Nov 26, 2019 11:15 pm

Imperf3kt wrote:
Tue Nov 26, 2019 9:17 pm
davidcoton wrote:
Tue Nov 26, 2019 9:11 pm
Poor guess. Many PD PSUs can only supply the full rated power at higher voltages, the current at 5V is just too high.
I don't see why. 5v 3A is listed in usb-c spec.
The Anker power supplies have all had very high regard here from dozens of forum users.
The USB-C spec requires 0A9, not 3A. The PD spec mentions 15W at 5V, and 60W at 20V (IIRC). Since the 60W figure does not allow full power on two sockets simultaneously at 20V, but only a total of 3A, does the same current limit apply across both ports at 5V, or can each port supply 3A? The spec is not clear about this, it would need to be tested. Or ask Anker that specific question before buying.

Also, the OP asked for "multiple" Pi4 supplies. Does two count as multiple?

My choice would be as @dustnbone suggested: an industrial supply, but with individual polyfuses for each Pi. It may also be that the cost of an official PSU for each Pi, together with multiple mains sockets, is cheaper and easier than a single PSU for all of them. Note that a single PSU introduces an additional single point of failure, which may or may not be significant in the OP's application.
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Imperf3kt
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Re: Power supply for multiple Pi4's needed. Advice?

Wed Nov 27, 2019 12:19 am

According to http://www.usb.org/developers/docs/ USB PD is at minimum 5v 3A
Since only one of the Anker ports is marked PD. The other port is separate.

I know its just guesswork, but to supply the 5v 3A so it can conform to USB PD specs, that PD marked port should deliver at least 5v 3A no matter what the other port is doing.


I'm just saying based on an observed guess and reports here from other users over the few years I have been here, I would trust that Anker power supply to power at least two Pi 4's, provided you use a non e-marked cable.

I'm not suggesting OP do so, nor am I suggesting the supply is the right choice, just that I would try it.
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rin67630
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Re: Power supply for multiple Pi4's needed. Advice?

Wed Nov 27, 2019 2:14 am

davidcoton wrote:
Tue Nov 26, 2019 11:15 pm
My choice would be as @dustnbone suggested: an industrial supply, but with individual polyfuses for each Pi.
Since that will need soldering anyway, you may want to consider my far preferred solution:
A step-down 3A adjustable buck converter for each Pi, fed from a salvaged 19V-4A old laptop power supply, that everybody surely already has in a drawer, or can find in quantities for free in every scrap yard.
The buck converters are usually less than 1$ each.

dustnbone
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Re: Power supply for multiple Pi4's needed. Advice?

Wed Nov 27, 2019 2:36 am

I should have mentioned fusing for sure, mostly to protect the wiring. The Mean Well supplies have short circuit/overcurrent protection built in but 20A is a bit much for a 22/24AWG wire. 5A polyfuses are cheap as chips. '

As for single point of failure, those supplies are well under rated and designed for decades of use in really harsh conditions. I work with industrial electronics all the time and I can't recall ever needing to replace a Mean Well supply, despite nearly every piece of equipment I work on having at least one installed. I'm comfortable stating they're at least 500% as reliable as any consumer wall wart.

Using individual buck converters from a common supply is a great idea, those converters can be had for under $1 if you need a few of them. They will also limit current, so I wouldn't think fusing after them necessary.

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