sdcruze
Posts: 1
Joined: Mon Feb 16, 2015 8:07 am

Power

Mon Feb 16, 2015 8:14 am

Hi all,

I am new to Raspberry Pi.

I have been playing with electronics commercially for a few years but I'm taking steps to train myself up more in my own time on the technical side of things.

Are all Raspberry Pi boards USB powered, or are there any mains/battery powered versions?

Thanks.

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

Re: Power

Mon Feb 16, 2015 8:35 am

All models of Pi are designed to be powered through the microUSB power connector, this cannot be used as a data connection.

If you wish you can back-power the Pi through the GPIO but this is not recommended as it bypasses the Pi's fuse.

You can use a USB powerbank to supply the microUSB power, thus giving you a battery supply.

Alternatively you could use any battery you like and condition the output to provide a stable 5v to power the Pi.

Often the power is supplied from a "wall wart" (mains plug adapter which outputs 5vdc).

You choose which method of powering you wish to use.
Doug.
Building Management Systems Engineer.

klricks
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Joined: Sat Jan 12, 2013 3:01 am
Location: Grants Pass, OR, USA
Contact: Website

Re: Power

Mon Feb 16, 2015 2:15 pm

Many people use old 5V phone chargers. At least 1A output but the RPi B+ and 2B can use up to 2A depending on what is attached to the USB. Higher amps is OK but the RPi won't and can't use more than 2A.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

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

Re: Power

Mon Feb 16, 2015 2:50 pm

klricks wrote:Many people use old 5V phone chargers. At least 1A output but the RPi B+ and 2B can use up to 2A depending on what is attached to the USB. Higher amps is OK but the RPi won't and can't use more than 2A.
I carefully avoided using the word "Charger" as these are not guaranteed to output 5v and a stable 5v input is necessary for the Pi.
Doug.
Building Management Systems Engineer.

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pluggy
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Location: Barnoldswick, Lancashire,UK
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Re: Power

Mon Feb 16, 2015 7:59 pm

Like it or like it not, putting 5V through a micro USB connector automatically brings it under the umbrella of charger. Many devices that will charge a phone, will not power a Pi, but most power supplies will also charge a phone. My 'holy' Swag store Pi 2A PSU is the best phone charger I have. For some reason my daughters tablet (a Tesco Hudl 2) won't entertain it but it will work with my Samsung 700mA charger, haven't quite fathomed that one yet. The swag store PSU is fairly generous on the voltage front (ideal Pi power supply ~5.2V) perhaps the Hudl is a bit picky voltage wise.
Don't judge Linux by the Pi.......
I must not tread on too many sacred cows......

klricks
Posts: 6615
Joined: Sat Jan 12, 2013 3:01 am
Location: Grants Pass, OR, USA
Contact: Website

Re: Power

Mon Feb 16, 2015 8:31 pm

pluggy wrote:Like it or like it not, putting 5V through a micro USB connector automatically brings it under the umbrella of charger. Many devices that will charge a phone, will not power a Pi, but most power supplies will also charge a phone. My 'holy' Swag store Pi 2A PSU is the best phone charger I have. For some reason my daughters tablet (a Tesco Hudl 2) won't entertain it but it will work with my Samsung 700mA charger, haven't quite fathomed that one yet. The swag store PSU is fairly generous on the voltage front (ideal Pi power supply ~5.2V) perhaps the Hudl is a bit picky voltage wise.
Some manufactures put bias on the data lines (pull up or down) in the charger as a way for the device to 'authenticate' the power supply. Some devices refuse to charge if the power supply does not match. I have an old phone that puts up a warning message about not having the proper charger but charges anyway.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

jimallyn
Posts: 51
Joined: Wed Nov 12, 2014 9:13 am

Re: Power

Mon Feb 16, 2015 8:37 pm

sdcruze, if you haven't yet purchased a Raspberry Pi, you might think about buying a kit containing the RPi, a power supply, a case, a wifi dongle, and so on. I bought one from Canakit, and the power supply is rated at 2.5 amps if I remember correctly, great plenty of power to run the Pi and any accessories you might have connected to it.
“So you say you love the poor? Name them.” - Gustavo Gutierrez

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