mbedford
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Powering multiple pi and boards

Fri Dec 08, 2017 4:28 pm

Not sure which area this is best posted to, but I am looking for recommendations for power supply solutions for powering more than just a single pi.

I am using a zero and a servo controller board which wants its own power not power from GPIO and potentially want to expand the solution with more boards etc...

I don't want multiple wall warts and I need to use a common ground so was looking to potentially use a single power supply in a similar fashion a I would do in an audio project and feed power to all internal boards with a star configuration.

Is this something that people have experience of?

Thanks

Martyn

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davidcoton
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Location: Cambridge, UK

Re: Powering multiple pi and boards

Fri Dec 08, 2017 4:44 pm

I haven't tried it, but there's no reson why you can't do exactly the same as with audio components.

Just be careful that your PSU can provide a stable 5-5.25V at the maximum total load, wires as short as possible and thick enough to avoid excessive voltage drop.

You can power your Zero through the GPIO 5V and ground pins, since there is no power protection to bypass (NOTE: this is a poor option for other Pi versions that do have onboard power protection).

You may want to distribute the power through individual fuses or polyfuses to add some protection.
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sparkie777
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Re: Powering multiple pi and boards

Fri Dec 08, 2017 5:47 pm

I power most of my raspberries 1/2/3 with these little UBEC things. E.g. either this one:

Amazon.com: Sanwood BEC UBEC 3A 5V Brushless Receiver Servo Power Supply for RC Airplane Aircraft: Toys & Games

or this one

UBEC DC/DC Step-Down (Buck) Converter - 5V @ 3A output ID: 1385 - $9.95 : Adafruit Industries, Unique & fun DIY electronics and kits

the attached 5V connector even fits directly to gpio Pins 4/6. The input voltage for the UBEC should range from 7V-26V (dependent on the model).

the UBEC should be mounted close to the raspberry. The voltage drop from UBEC to the power supply (e.g. providing 18V) is of minor impact. You can use long and thin leads for this provided at least 7V reach the UBEC under full load. Many raspberries could be hooked up to one power supply this way unless you exceed the max. current allowed for the supply.

you even can feed the power via an existing ethernet cable (kind of homebrew power-over-ethernet). Since we need only 4 of 8 wires for the ethernet 100Mbit/s itself the remaining 4 leads then are free for supplying power to the UBEC.
Last edited by sparkie777 on Mon Dec 11, 2017 5:13 pm, edited 5 times in total.

alphanumeric
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Re: Powering multiple pi and boards

Fri Dec 08, 2017 10:03 pm

I use a 5V 10 A, https://www.adafruit.com/product/658 on my bread boarding Pi setup. I feed power to my Pi and other items via a panel mount barrel jack, https://www.adafruit.com/product/610 It powers my Pi 3B, Pi foundation 7 inch touch screen, Analog audio amp, and any USB devices I plug in. I made up my own custom cables. I installed poly fuses where I felt they were needed. I also use the 5 V 4A version of the supply I linked to above on another PI project. It's a portable unit with a powerboost and 6600 MAH LIPO battery. 4A lets me charge the battery and run the Pi at the same time.

k-pi
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Re: Powering multiple pi and boards

Sat Dec 09, 2017 1:02 pm

I've used a powered USB hub to power a RPi3 & HDD at the same time, maybe one could do what you are looking for.

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HawaiianPi
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Re: Powering multiple pi and boards

Sat Dec 09, 2017 6:32 pm

k-pi wrote:
Sat Dec 09, 2017 1:02 pm
I've used a powered USB hub to power a RPi3 & HDD at the same time, maybe one could do what you are looking for.
Not a good idea, as most hubs will not output enough current to power a Pi3 when heavily loaded (USB 2.0 hubs are only 500mA per port, and USB 3.0 hubs are only 900mA). With a proper power supply the Pi3 should be able to power a portable HDD directly. I've done it many times. The Pi3 USB ports can supply up to 1.2A combined (with no per-port limits).
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jcyr
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Re: Powering multiple pi and boards

Sat Dec 09, 2017 8:35 pm

Supplies aside, I'm curious where you guys hook up the power. Via micro-USB, or via power pins on the header?

In other words, with or without fuse?
It's um...uh...well it's kinda like...and it's got a bit of...

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davidcoton
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Re: Powering multiple pi and boards

Sat Dec 09, 2017 11:15 pm

jcyr wrote:
Sat Dec 09, 2017 8:35 pm
Supplies aside, I'm curious where you guys hook up the power. Via micro-USB, or via power pins on the header?

In other words, with or without fuse?
OP concerns a Pi Zero which has no power protection. For other models use the micro-USB whenever possible, it might save your Pi one day.
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alphanumeric
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Re: Powering multiple pi and boards

Sun Dec 10, 2017 10:12 am

jcyr wrote:
Sat Dec 09, 2017 8:35 pm
Supplies aside, I'm curious where you guys hook up the power. Via micro-USB, or via power pins on the header?

In other words, with or without fuse?
I try to use the Pi's Micro USB power port where possible. I have one setup where I power several devices separately from the one power supply. I added my own poly fuses where I thought they were needed.

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