Petingo
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Pi 3 power supply & USB cable

Fri Mar 04, 2016 12:32 pm

Hello,
I'm a beginner and going to buy a Pi 3

The introduction says that it needs at least [email protected]
However, I get only a 1.5A cellphone charger… will it works fine?

Another question is that if I got a [email protected] adapter, will a general USB cable like my cellphone using works fine?

Any reply will be appreciate, thanks a lot 

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GTR2Fan
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Re: Pi 3 power supply & USB cable

Fri Mar 04, 2016 1:25 pm

Petingo wrote:The introduction says that it needs at least [email protected]
However, I get only a 1.5A cellphone charger… will it works fine?
Doubtful on two counts...

1/ 1.5A is obviously a long way short of 2.5A.
2/ A charger isn't necessarily designed to be a power supply.
Another question is that if I got a [email protected] adapter, will a general USB cable like my cellphone using works fine?
Maybe. You'll have to try it to find out. Ideally, you need a short USB cable specifically designed for fast charging or power delivery as opposed to a standard data cable.
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Re: Pi 3 power supply & USB cable

Fri Mar 04, 2016 1:35 pm

It might work, 2.5A is for extreme conditions - USB hard drive, lots of USB peripherals attached. 1.5A may be enough. I'm using a Pi2 supply with no issues.

But official power supplies are relatively cheap...
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Re: Pi 3 power supply & USB cable

Fri Mar 04, 2016 1:40 pm

If i remember correctly allot of problems that people can have with a Pi are related to insufficient power supply.
So please do yourself a favor and get a proper official Raspberry power supply:

http://thepihut.com/collections/raspber ... wer-supply

https://shop.pimoroni.com/products/rasp ... wer-supply

https://www.kiwi-electronics.nl/rpi-psu ... -5a--eu-uk

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Re: Pi 3 power supply & USB cable

Fri Mar 04, 2016 1:42 pm

http://thepihut.com/collections/raspber ... wer-supply
Its a great power supply 5.1v 2.5A and only £6.
It comes with a decent cable attached and the correct micro-usb plug of course.
Last edited by jahboater on Fri Mar 04, 2016 1:43 pm, edited 1 time in total.
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chrisoh
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Re: Pi 3 power supply & USB cable

Fri Mar 04, 2016 1:43 pm

An article, on Hackaday I think, reported Pi 3 using 720mA as "maximum power consumption at boot" IIRC, so a 1.5A supply should, in theory, be ample for general use I would have thought. I'll dig out my voltmeter later and have a play with some peripherals and find out some numbers.

Edit:
Hackaday article: http://hackaday.com/2016/03/01/pi-3-ben ... e-is-true/
Amended 750mA to 720mA and "idle" to "maximum power consumption at boot"
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  • Minecraft 1.9 Server +100mA
  • 2.4Ghz dongle +20mA

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Re: Pi 3 power supply & USB cable

Fri Mar 04, 2016 6:38 pm

chrisoh wrote:An article, on Hackaday I think, reported Pi 3 using 720mA as "maximum power consumption at boot" IIRC, so a 1.5A supply should, in theory, be ample for general use I would have thought. I'll dig out my voltmeter later and have a play with some peripherals and find out some numbers.

Edit:
Hackaday article: http://hackaday.com/2016/03/01/pi-3-ben ... e-is-true/
Amended 750mA to 720mA and "idle" to "maximum power consumption at boot"
The 1.5A charger is probably still marginal. The "power budget" for Pi3B was posted as: 1A for the SoC/RAM, 0.3A for WiFi/BT, and 1.2A for full powered to USB. If the increased USB power is NOT selected, then the expected max current would be 1.9A and a good 2A supply would cover it. At 1.5A, it'd be a good idea to disable the WiFi and BT modules as well as not trying to drive the SoC all out, or only use very low power USB devices. Alternatively, leave BT active for wireless keyboard and mouse and don't use *any* USB devices.

It would be an interesting exercise to see how low you can hold the input current without imposing outrageous limits on what you can do with the system.

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Re: Pi 3 power supply & USB cable

Fri Mar 04, 2016 6:48 pm

I am using a 1.5 AMP power supply for a Pi3. It's using WiFi and has a keyboard and mouse plugged in and it is 100% fine.
I also have another power supply that claims to supply 2AMPs, and it was occasionally giving me the rainbow square.

I think the quality of the power supply has a good deal to do with the performance, a stable voltage is needed as is the ability of a switching circuit to respond quickly to sudden higher current draw. A good, short cable also helps.

But as already mentioned, if you are going to be powering more than just a keyboard and mouse through USB and or you are using the official display panel then get the proper one.

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Re: Pi 3 power supply & USB cable

Fri Mar 04, 2016 8:17 pm

W. H. Heydt wrote:The "power budget" for Pi3B was posted as: 1A for the SoC/RAM, 0.3A for WiFi/BT, and 1.2A for full powered to USB
Where do these numbers originate?
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  • 2.4Ghz dongle +20mA

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Re: Pi 3 power supply & USB cable

Fri Mar 04, 2016 8:33 pm

chrisoh wrote:
W. H. Heydt wrote:The "power budget" for Pi3B was posted as: 1A for the SoC/RAM, 0.3A for WiFi/BT, and 1.2A for full powered to USB
Where do these numbers originate?
The official Q&A thread stickied at the top of this Forum.

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Re: Pi 3 power supply & USB cable

Fri Mar 04, 2016 8:50 pm

W. H. Heydt wrote:
chrisoh wrote:
W. H. Heydt wrote:The "power budget" for Pi3B was posted as: 1A for the SoC/RAM, 0.3A for WiFi/BT, and 1.2A for full powered to USB
Where do these numbers originate?
The official Q&A thread stickied at the top of this Forum.
Thanks but do you have a link to a post, I must be blind but I can only find a reference to a comment on the blog?
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Petingo
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Re: Pi 3 power supply & USB cable

Sat Mar 05, 2016 3:54 am

Thanks everyone a lot!
I think i'll buy the official power supply for it, and i'll still try the 1.5A and other though. :D

carlhung
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Re: Pi 3 power supply & USB cable

Sat Mar 05, 2016 7:57 am

Is any good power supply for overclock?
What voltages would you suggest for overclock? Thanks.

apache
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Re: Pi 3 power supply & USB cable

Sat Mar 05, 2016 10:27 am

Hi,

I received my RPi 3 yesterday. I bought it without power supply. And that was mistake. I tried a few chargers. All rated 1.5-2A (only branded ones - like ASUS, LG, HTC) - and got a lot problems with it. I tried a few cables. I tried even my bench 5A power supply - and still got problems. Right now I'm powering my Pi 3 from 0.7A power supply from mikrotik router - and it seams to work fine - no power errors at all. After weekend I must order something better. So my advice for every buyer - buy your Pi 3 with original power supply.

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Re: Pi 3 power supply & USB cable

Sat Mar 05, 2016 12:00 pm

apache wrote:Hi,

I received my RPi 3 yesterday. I bought it without power supply. And that was mistake. I tried a few chargers. All rated 1.5-2A (only branded ones - like ASUS, LG, HTC) - and got a lot problems with it. I tried a few cables. I tried even my bench 5A power supply - and still got problems. Right now I'm powering my Pi 3 from 0.7A power supply from mikrotik router - and it seams to work fine - no power errors at all. After weekend I must order something better. So my advice for every buyer - buy your Pi 3 with original power supply.
All seems rather counter-intuitive :lol: whatever works though, right?!
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  • HDMI +200mA
  • Minecraft 1.9 Server +100mA
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Re: Pi 3 power supply & USB cable

Sat Mar 05, 2016 12:31 pm

apache wrote:I tried even my bench 5A power supply - and still got problems. Right now I'm powering my Pi 3 from 0.7A power supply from mikrotik router - and it seams to work fine - no power errors at all.
That doesn't make a lot of sense other than you may have connected them differently, the problem being in that connection or cable used when using the bench supply. Otherwise it would not seem to be a very good bench supply or, though rated at 5A, is current limiting lower than that.

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Re: Pi 3 power supply & USB cable

Sat Mar 05, 2016 12:39 pm

W. H. Heydt wrote:
chrisoh wrote:
W. H. Heydt wrote:The "power budget" for Pi3B was posted as: 1A for the SoC/RAM, 0.3A for WiFi/BT, and 1.2A for full powered to USB
Where do these numbers originate?
The official Q&A thread stickied at the top of this Forum.
Either the post has gone or it was perhaps somewhere else. I searched all 15 pages of the Pi 3 Q&A thread and couldn't find 1A for the SoC/RAM, 0.3A for WiFi/BT figures stated.

I am not saying the figures are wrong because they are in the ballpark of what I recall reading but not sure where.

The Pimoroni figures suggest 750mA when running sysbench on a Pi 3, which I took as board-wide consumption, so I would have presumed a 1.5A supply to be sufficient without additional USB load and a less than maxed-out Pi 3.

http://blog.pimoroni.com/raspberry-pi-3

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Re: Pi 3 power supply & USB cable

Sat Mar 05, 2016 12:58 pm

https://www.raspberrypi.org/help/faqs - Pi 3B, Amps ...

Boot Max 0.75
Idle Avg 0.30
Video playback (H.264) Max 0.55
Stress Max 1.34

Test conditions used a standard Raspbian image (current as of 26 Feb 2016), at room temperature, connected to a HDMI monitor, USB keyboard and mouse. For the Model 3B it was connected to a WiFi access point. All these power measurements do not take into account power consumption from additional USB devices

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Re: Pi 3 power supply & USB cable

Sat Mar 05, 2016 1:01 pm

hippy wrote:The Pimoroni figures suggest 750mA when running sysbench on a Pi 3, which I took as board-wide consumption, so I would have presumed a 1.5A supply to be sufficient without additional USB load and a less than maxed-out Pi 3.
Although the Pimoroni figures are interesting, they're not the result of a stress test so only tell you what the current consumption is under a known but nowhere near maximum CPU load. They also ignore current consumption relating to GPU load. They only tell a small part of the story.
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chrisoh
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Re: Pi 3 power supply & USB cable

Sat Mar 05, 2016 1:28 pm

hippy wrote:
W. H. Heydt wrote:The official Q&A thread stickied at the top of this Forum.
Either the post has gone or it was perhaps somewhere else. I searched all 15 pages of the Pi 3 Q&A thread and couldn't find 1A for the SoC/RAM, 0.3A for WiFi/BT figures stated.

I am not saying the figures are wrong because they are in the ballpark of what I recall reading but not sure where.

The Pimoroni figures suggest 750mA when running sysbench on a Pi 3, which I took as board-wide consumption, so I would have presumed a 1.5A supply to be sufficient without additional USB load and a less than maxed-out Pi 3.

http://blog.pimoroni.com/raspberry-pi-3
I'll hazard a guess that W. H. Heydt quoted it from a comment made by a "Gordon Hollingworth" on 1st Mar 2016 at 6:58 am on the https://www.raspberrypi.org/blog/raspbe ... 3-on-sale/ blog post:
Gordon Hollingworth wrote:There is only one recommended power adapter, the 2.5A Raspberry Pi power adapter. But the power consumption is based on 1A to the processor plus 0.3A to the WiFi plus 1.2A to the USB

These are peak values only but of course you can easily get close to those numbers playing software decoded video for example (youtube on chromium!)
Safe to assume Gordon was guestimating by deduction: 2.5 - 0.3 - 1.2 = 1A remaining for the processor.

If you're not sucking all 1.2A from the USB ports then my everyday use so far shows a 2A supply is fine (others reporting a Pi 2 supply is OK likewise). Time to fire up my neural net and see what happens I think... :lol:
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  • HDMI +200mA
  • Minecraft 1.9 Server +100mA
  • 2.4Ghz dongle +20mA

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Re: Pi 3 power supply & USB cable

Sat Mar 05, 2016 3:46 pm

I'll hazard a guess that W. H. Heydt quoted it from a comment made by a "Gordon Hollingworth" on 1st Mar 2016 at 6:58 am on the https://www.raspberrypi.org/blog/raspbe ... 3-on-sale/ blog post:
Gordon Hollingworth is Director of Software Engineering at the Raspberry Pi Foundation!
He should know.

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Re: Pi 3 power supply & USB cable

Sat Mar 12, 2016 8:32 pm

apache wrote:Hi,

I received my RPi 3 yesterday. I bought it without power supply. And that was mistake. I tried a few chargers. All rated 1.5-2A (only branded ones - like ASUS, LG, HTC) - and got a lot problems with it. I tried a few cables. I tried even my bench 5A power supply - and still got problems. Right now I'm powering my Pi 3 from 0.7A power supply from mikrotik router - and it seams to work fine - no power errors at all. After weekend I must order something better. So my advice for every buyer - buy your Pi 3 with original power supply.
I've just tried my RPi 3 with the official power supply from the PiHut and not getting past the rainbow square at boot (only HDMI attached, no USB devices, using an 8GB SD card with OSMC installed). Very odd - not sure if it's a faulty power supply.

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Re: Pi 3 power supply & USB cable

Sun Apr 03, 2016 2:26 am

colinmower wrote:Very odd - not sure if it's a faulty power supply.
Any update on this issue?

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Re: Pi 3 power supply & USB cable

Sun Apr 03, 2016 3:18 am

colinmower wrote:
apache wrote:Hi,

I received my RPi 3 yesterday. I bought it without power supply. And that was mistake. I tried a few chargers. All rated 1.5-2A (only branded ones - like ASUS, LG, HTC) - and got a lot problems with it. I tried a few cables. I tried even my bench 5A power supply - and still got problems. Right now I'm powering my Pi 3 from 0.7A power supply from mikrotik router - and it seams to work fine - no power errors at all. After weekend I must order something better. So my advice for every buyer - buy your Pi 3 with original power supply.
I've just tried my RPi 3 with the official power supply from the PiHut and not getting past the rainbow square at boot (only HDMI attached, no USB devices, using an 8GB SD card with OSMC installed). Very odd - not sure if it's a faulty power supply.
Is there an OSMC version for the Pi3? At launch, so far as I recall, only Raspbian was ready to go.

I would suggest trying your physical setup (Pi3B+PSU) with the current Raspbian to see if that boots okay. The big colored square is the VC4 start of boot image and remaining there usually means that it can't find an executable it needs.

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Re: Pi 3 power supply & USB cable

Sun Apr 10, 2016 6:11 pm

I have a pi 3.
Was using a 2A powersupply and getting rainbow cube.
bought an "official" 2.4a supply from MCM with a 2nd rpi3 and still get the rainbow when I compile things with more than one core or other cpu intensive tasks.

Not sure what to do now other than buy what?
a 3 amp powerbrick?

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