kapurvish
Posts: 15
Joined: Wed Jul 30, 2014 11:05 am

Raspberry Pi B+ Power Supply

Wed Jul 30, 2014 12:59 pm

I am planning to buy Raspberry Pi B+.The power requirement says: Power supply: +5V @ 2A via microUSB socket

Can i buy a USB power adapter with output as: 5V and 2.1A,please suggest??

User avatar
mahjongg
Forum Moderator
Forum Moderator
Posts: 14726
Joined: Sun Mar 11, 2012 12:19 am
Location: South Holland, The Netherlands

Re: Raspberry Pi B+ Power Supply

Wed Jul 30, 2014 1:13 pm

yes, more current capability is allowed, but isn't used.

2.1Amp is fine.

if the output is simply a standard USB connector, then buy the shortest and thickest USB to microUSB cable you can find, as long and thin power cables often cause problems due to their cheapness they contain only minimal sized copper wires.

User avatar
Gert van Loo
Posts: 2487
Joined: Tue Aug 02, 2011 7:27 am

Re: Raspberry Pi B+ Power Supply

Wed Jul 30, 2014 1:35 pm

I assume they are being cautious as the new B+ uses less power then the old B.
I am sure a 1A supply will also work.
You just won't be able to draw as much current from the USB ports.

kapurvish
Posts: 15
Joined: Wed Jul 30, 2014 11:05 am

Re: Raspberry Pi B+ Power Supply

Wed Jul 30, 2014 1:51 pm

Thanks, but i would be using a USB Mouse and keyboard, so that would also consume power.

User avatar
pluggy
Posts: 3635
Joined: Thu May 31, 2012 3:52 pm
Location: Barnoldswick, Lancashire,UK

Re: Raspberry Pi B+ Power Supply

Wed Jul 30, 2014 2:08 pm

700mA works fine for a mouse, keyboard and wifi adaptor for me....
Don't judge Linux by the Pi.......
I must not tread on too many sacred cows......

User avatar
FTrevorGowen
Forum Moderator
Forum Moderator
Posts: 7026
Joined: Mon Mar 04, 2013 6:12 pm
Location: Bristol, U.K.

Re: Raspberry Pi B+ Power Supply

Wed Jul 30, 2014 2:11 pm

kapurvish wrote:Thanks, but i would be using a USB Mouse and keyboard, so that would also consume power.
That should not be a problem** (even with a 1A supply - the B+ uses less power "for itself" than a B and all my B's work fine with good**** 1A supplies).
Trev.
** basic wired (cheap & cheerful) keyboards and mice only require a few 10's of mA. Wireless ones with extra leds, hubs, bells, whistles :) ... sometimes require too much for a B (not a B+)
**** those that still provide >4.75V at 1A.
Still running Raspbian Jessie or Stretch on some older Pi's (an A, B1, 2xB2, B+, P2B, 3xP0, P0W, 2xP3A+, P3B, B+, and a A+) but Buster on the P3B+, P4B's & P400. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

kapurvish
Posts: 15
Joined: Wed Jul 30, 2014 11:05 am

Re: Raspberry Pi B+ Power Supply

Wed Jul 30, 2014 2:16 pm

But why on B+ Pi its said: Power supply: +5V @ 2A via microUSB socket

User avatar
FTrevorGowen
Forum Moderator
Forum Moderator
Posts: 7026
Joined: Mon Mar 04, 2013 6:12 pm
Location: Bristol, U.K.

Re: Raspberry Pi B+ Power Supply

Wed Jul 30, 2014 2:27 pm

kapurvish wrote:But why on B+ Pi its said: Power supply: +5V @ 2A via microUSB socket
The extra current available (above the ~600mA the B+ uses itself) is for any other devices plugged into the USB ports or powered via the GPIO connector ie. the 2A is a "maximum allowed current"** flowing into and through the Pi. (For a B this was <1A**)
Trev.
** Higher currents would trip the polyfuse.
Still running Raspbian Jessie or Stretch on some older Pi's (an A, B1, 2xB2, B+, P2B, 3xP0, P0W, 2xP3A+, P3B, B+, and a A+) but Buster on the P3B+, P4B's & P400. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 31815
Joined: Sat Jul 30, 2011 7:41 pm

Re: Raspberry Pi B+ Power Supply

Wed Jul 30, 2014 2:40 pm

For example, my B+ has a mouse, keyboard and WiFi adapter, and works fine at 1A, But when I plug in a USB HD, it doesn't work unless I use a 2A power supply.

So it depends on what you plug in.
Principal Software Engineer at Raspberry Pi Ltd.
Working in the Applications Team.

wh7qq
Posts: 1580
Joined: Thu Oct 09, 2014 2:50 am

Re: Raspberry Pi B+ Power Supply

Tue Nov 18, 2014 1:00 am

I have successfully used an rpi B+ with an Iomagic wireless keyboard w/integral trackball and a 16G usb memory stick on a 750 ma phone charger. Your mileage may vary.

W. H. Heydt
Posts: 16093
Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: Raspberry Pi B+ Power Supply

Tue Nov 18, 2014 6:46 am

wh7qq wrote:I have successfully used an rpi B+ with an Iomagic wireless keyboard w/integral trackball and a 16G usb memory stick on a 750 ma phone charger. Your mileage may vary.
Sure... I have a wireless keyboard and mouse around here somewhere that I used a bit early on with a very early Model B. As I recall, the dongle is rated to draw less than 10mA. After all, when you're using a wireless keyboard, the Pi is only powering the dongle, not the keyboard itself.

boyoh
Posts: 1717
Joined: Fri Nov 23, 2012 3:30 pm
Location: Selby. North Yorkshire .UK

Re: Raspberry Pi B+ Power Supply

Tue Nov 18, 2014 3:32 pm

kapurvish wrote:I am planning to buy Raspberry Pi B+.The power requirement says: Power supply: +5V @ 2A via microUSB socket

Can i buy a USB power adapter with output as: 5V and 2.1A,please suggest??


Don't skimp on your power supply
Better to have some power in reserve
than non atoll
Raspberry Pi Universal Power Supply
+5V 2A output provides all the power your Pi will need
1.5m cable gives your Pi room to manoeuvre
Micro USB connection goes straight into your Pi's power supply
BoyOh ( Selby, North Yorkshire.UK)
Some Times Right Some Times Wrong

User avatar
pluggy
Posts: 3635
Joined: Thu May 31, 2012 3:52 pm
Location: Barnoldswick, Lancashire,UK

Re: Raspberry Pi B+ Power Supply

Tue Nov 18, 2014 3:41 pm

The fact that the micro-USB port is capable of a maximum current of 1.5 A (or 1.8 A if you work on the older specification) is irrelevant I Suppose . You may have noticed that many tablets on the market don't use micro USB for this reason. It just isn't big enough.

Back in the old days when the Pi B used 400 mA, a 700mA power supply was deemed sufficient. Nowadays with the Pi B+ using 250 mA you need a 2A supply. It might give you enough to run a BUS powered USB HDD, it might not.

What it says on the label, especially if it was cheap, means precisely nothing. I think the reasoning behind insisting on a 2A supply is that it stands a better chance of supplying the ~ 600 mA current required by the average Pi setup when the label is lying through it's teeth....

Sheesh, I'm cynical today, probably an excess of caffeine........
Don't judge Linux by the Pi.......
I must not tread on too many sacred cows......

User avatar
Burngate
Posts: 6541
Joined: Thu Sep 29, 2011 4:34 pm
Location: Berkshire UK Tralfamadore

Re: Raspberry Pi B+ Power Supply

Tue Nov 18, 2014 5:47 pm

pluggy wrote:Sheesh, I'm cynical today, probably an excess of caffeine........
... or maybe not enough?

Have another coffee, see if it gets better or worse, and report back.

User avatar
pluggy
Posts: 3635
Joined: Thu May 31, 2012 3:52 pm
Location: Barnoldswick, Lancashire,UK

Re: Raspberry Pi B+ Power Supply

Tue Nov 18, 2014 6:01 pm

I probably aren't going to sleep tonight as it is. Had a couple of seriously good coffees at a local emporium, I know from experience they have enough caffeine in 'em to sink a battleship.
Don't judge Linux by the Pi.......
I must not tread on too many sacred cows......

boyoh
Posts: 1717
Joined: Fri Nov 23, 2012 3:30 pm
Location: Selby. North Yorkshire .UK

Re: Raspberry Pi B+ Power Supply

Tue Nov 18, 2014 6:25 pm

pluggy wrote:The fact that the micro-USB port is capable of a maximum current of 1.5 A (or 1.8 A if you work on the older specification) is irrelevant I Suppose . You may have noticed that many tablets on the market don't use micro USB for this reason. It just isn't big enough.

Back in the old days when the Pi B used 400 mA, a 700mA power supply was deemed sufficient. Nowadays with the Pi B+ using 250 mA you need a 2A supply. It might give you enough to run a BUS powered USB HDD, it might not.

What it says on the label, especially if it was cheap, means precisely nothing. I think the reasoning behind insisting on a 2A supply is that it stands a better chance of supplying the ~ 600 mA current required by the average Pi setup when the label is lying through it's teeth....

Sheesh, I'm cynical today, probably an excess of caffeine........
It is getting to the point where we
don't believe what we read about
the specifications on the name plate.
I notice it is mainly the experienced
That doubt what they read, and the
novice takes it for granted. he knows
no better
So we are in a" Tight spot," what do we tell him.
Two different make power supply's, with
the same specification, Is " A " better
than " B " Or " B " better than " A"
BoyOh ( Selby, North Yorkshire.UK)
Some Times Right Some Times Wrong

W. H. Heydt
Posts: 16093
Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: Raspberry Pi B+ Power Supply

Tue Nov 18, 2014 6:42 pm

boyoh wrote:
pluggy wrote:The fact that the micro-USB port is capable of a maximum current of 1.5 A (or 1.8 A if you work on the older specification) is irrelevant I Suppose . You may have noticed that many tablets on the market don't use micro USB for this reason. It just isn't big enough.

Back in the old days when the Pi B used 400 mA, a 700mA power supply was deemed sufficient. Nowadays with the Pi B+ using 250 mA you need a 2A supply. It might give you enough to run a BUS powered USB HDD, it might not.

What it says on the label, especially if it was cheap, means precisely nothing. I think the reasoning behind insisting on a 2A supply is that it stands a better chance of supplying the ~ 600 mA current required by the average Pi setup when the label is lying through it's teeth....

Sheesh, I'm cynical today, probably an excess of caffeine........
It is getting to the point where we
don't believe what we read about
the specifications on the name plate.
I notice it is mainly the experienced
That doubt what they read, and the
novice takes it for granted. he knows
no better
So we are in a" Tight spot," what do we tell him.
Two different make power supply's, with
the same specification, Is " A " better
than " B " Or " B " better than " A"
We *test* the devices (or tell someone else to test them) and then report the results. This is why I think an inexpensive "load cell" would be a viable product. With the B+ on the market with a 2A poly fuse, having a choice between a 5 ohm and a 2.5 ohm load and easy to use test points one could determine what a proposed "power supply" and/or cable will do under full load, even if it's a static load. While such a load cell could be built using LEDs as "idiot lights", I'd prefer to have (or have in addition) a way to do a hands free attachment of meter leads.

chintanp
Posts: 5
Joined: Fri Dec 05, 2014 7:38 am

Re: Raspberry Pi B+ Power Supply

Fri Dec 05, 2014 7:51 am

I was using the power supply provided along with CrazyPi.com Scientific Kit which is a 2Amp 5V supply.

My Pi boots fine with the HDMI output, but didnt boot with a RCA cable connected to a externally powered TFT, but it booted in this configuration, when I powered the PI thru the USB port of my PC. So I am guessing that that adapter didnt supply enough current.

Although, the FAQ pages say that B+ would rarely need more current, I have found a case, where it does, so I am gonna try with a 5A, 5V charger, and see how it does.

I am guessing more current shouldnt be a problem as long as the voltage is 5V, which answers the OP's question.

User avatar
rurwin
Forum Moderator
Forum Moderator
Posts: 4257
Joined: Mon Jan 09, 2012 3:16 pm

Re: Raspberry Pi B+ Power Supply

Fri Dec 05, 2014 11:49 am

chintanp wrote:I am guessing more current shouldnt be a problem as long as the voltage is 5V, which answers the OP's question.
You are guessing correctly. The way electricity works, the RaspPi will only draw the current it needs. The only reason you may want a power supply with a lower current is because it is cheaper. My desktop power supply is good for 8 amps, the RaspPi still only takes its 0.7 amps or whatever.

Magnusth
Posts: 1
Joined: Fri Dec 19, 2014 2:03 am

Re: Raspberry Pi B+ Power Supply

Fri Dec 19, 2014 2:08 am

Sorry for bringing this up again, but this kinda got me confused(yes i just bought a Pi b+ today, and i dont want to wreck it the first day. Also this is my first, so i am trying to learn it all for school )

I have a 5.1V and 2.1A power suply. Will it work?

I understood the 2.1A would not be a problem, but i get mixed signals on the voltage, if >5 is to high.
Could anyone please help a noob? :)

Thank you in advance

W. H. Heydt
Posts: 16093
Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: Raspberry Pi B+ Power Supply

Fri Dec 19, 2014 6:25 am

Magnusth wrote:Sorry for bringing this up again, but this kinda got me confused(yes i just bought a Pi b+ today, and i dont want to wreck it the first day. Also this is my first, so i am trying to learn it all for school )

I have a 5.1V and 2.1A power suply. Will it work?

I understood the 2.1A would not be a problem, but i get mixed signals on the voltage, if >5 is to high.
Could anyone please help a noob? :)

Thank you in advance
That will be okay. The actual voltage spec is "5v+/-10%", so anything from 4.75v to 5.25v is "within spec".

In practice, no power supply is going to be *precisely* 5v (or any other specific voltage). In addition, power supplies and cables have internal resistance (that's why all the comments about short, thick cables...less resistance), so as you load the power supply, the voltage will drop. For a good power supply, it will only drop a little bit. For a poor quality one, it may drop a whole lot.

The net result is that an overrated power supply (say 2A to 2.5A) will actually deliver at or very near 5v under the 600mA that the Pi will draw under most circumstances.

Jaace
Posts: 2
Joined: Sun Dec 28, 2014 3:30 am

Re: Raspberry Pi B+ Power Supply

Sun Dec 28, 2014 3:33 am

I have a Samsung Travel Adapter (ETA0U60JBE) that has an output of 5.0V, 0.7A and a Raspberry Pi Model B+.

1) Is this possible / safe to use if I'm not trying to run anything beyond a keyboard/mouse input and HDMI to a monitor?

2) Will I run into trouble if I add more peripherals?

User avatar
rpdom
Posts: 20859
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Raspberry Pi B+ Power Supply

Sun Dec 28, 2014 6:15 am

Jaace wrote:I have a Samsung Travel Adapter (ETA0U60JBE) that has an output of 5.0V, 0.7A and a Raspberry Pi Model B+.

1) Is this possible / safe to use if I'm not trying to run anything beyond a keyboard/mouse input and HDMI to a monitor?
It should be enough as long as it really can manage 5V at 0.7A. A lot of adaptors can't manage the full 5V when you try to take more current, which isn't critical when charging a phone, it'll just take longer to charge, but on a Pi it can cause crashes.

Try it and see. If it isn't good enough you may see you Pi crash or reboot, the worst it can do is corrupt the SD card so you have to re-write it from scratch. It can't damage the Pi.
2) Will I run into trouble if I add more peripherals?
Maybe. Certainly you will if you add high-current peripherals like some WiFi dongles or a USB disk without its own PSU or a powered HUB. Again, try and see.

A higher current PSU (2.0A) is recommended because people have found lower current ones to be unreliable in a lot of cases. It does depend what you use it or though. I have run a Pi off a Samsung charger for days without a problem, but I didn't have anything connected to USB.

Jaace
Posts: 2
Joined: Sun Dec 28, 2014 3:30 am

Re: Raspberry Pi B+ Power Supply

Sun Dec 28, 2014 3:06 pm

Thanks for the reply! I found a slightly higher amperage usb plug to use (iphone charger at 1A) in the interim until I order the official power supply from Raspberry Pi.

klricks
Posts: 8549
Joined: Sat Jan 12, 2013 3:01 am
Location: Grants Pass, OR, USA

Re: Raspberry Pi B+ Power Supply

Sun Dec 28, 2014 5:44 pm

Jaace wrote:Thanks for the reply! I found a slightly higher amperage usb plug to use (iphone charger at 1A) in the interim until I order the official power supply from Raspberry Pi.
Strictly speaking there is no 'official' power supply. The only official products are these: http://www.raspberrypi.org/products/ The Raspberry Pi Foundation does not really sell anything but have liceneced the manufacturing and selling to a few specific distributors shown in the link.
The RPF gives only suggested power requirements: http://www.raspberrypi.org/help/faqs/#powerReqs

It's up to you to follow the suggestions and specifications when looking for any accessories. Most of the time if you buy from a well known source then you are OK. It's ''hit and miss' if you buy stuff from 'Ebay / China etc.
Unless specified otherwise my response is based on the latest and fully updated RPi OS Bullseye w/ Desktop OS.

Return to “Beginners”