flameboy5073
Posts: 18
Joined: Tue Jul 31, 2012 2:47 pm

Power Supply will it work?

Tue Jul 31, 2012 6:34 pm

Hi guys this is my first post (I hope I've put it in the right category)! All I want to know is will this http://www.amazon.co.uk/PortaPow-Mains- ... 355&sr=8-1 power supply work on the raspberry pi?

Thanks :ugeek:

User avatar
joan
Posts: 14469
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Power Supply will it work?

Tue Jul 31, 2012 7:29 pm

It should do.

User avatar
tvinzant
Posts: 14
Joined: Fri Jul 27, 2012 3:10 am
Location: USA

Re: Power Supply will it work?

Tue Jul 31, 2012 7:34 pm

The specs are correct. "1000mA 5V output"
I can't tell if that's a micro USB connection from the photo and there is no specific mention of micro USB in the description.

You should be good to go "IF" you have a micro USB connection on the RPI end of the charger.

Just to pass along some additional information.
I saw the following where Eben mentions he uses a Kindle Charger.
http://youtu.be/89sZvgI4AfU

User avatar
mahjongg
Forum Moderator
Forum Moderator
Posts: 12398
Joined: Sun Mar 11, 2012 12:19 am
Location: South Holland, The Netherlands

Re: Power Supply will it work?

Tue Jul 31, 2012 7:36 pm

Hmmm. it actually states its "for a raspberry PI" :D
At 1A and 5V (I assume these are actual values not "chinese labeling") it should be fine, as long as the 5V output doesn't dip under 4.9 Volt at maximum load, and the amount of ripple on the 5V is negligible.

flameboy5073
Posts: 18
Joined: Tue Jul 31, 2012 2:47 pm

Re: Power Supply will it work?

Thu Aug 02, 2012 7:15 pm

The power supply arrived today I can confirm that the 5V and 1000mA are both true and the micro usb end fits my raspberry pi. All in all a great little buy, I would reccomend.

:ugeek:

kriston
Posts: 12
Joined: Sat Aug 25, 2012 3:05 am

Re: Power Supply will it work?

Sun Sep 23, 2012 3:16 am

I have found that the length and quality of the cable matters if you expect to plug anything into the USB ports of the Raspberry Pi. I have lots of cables but the only ones that work reliably are of the three-foot variety.

I don't really know why, but when I use cables that are longer than three feet, they only work if plugged into a computer's USB hub and not a USB power supply such as the Nook Color charger. But, using the same charger and a shorter cable usually works. It's weird but not unexpected.

Note that in this situation I have a USB keyboard and a USB mouse connected to the Pi. The USB keyboard is an ultra-micro keyboard which draws a negligible amount of current. I've also tried higher-power-draw keyboards to see if this is a fluke but have concluded that, indeed, the length of the cable matters, and I don't like that sort of variability.

Thanks for the information.

tberg53
Posts: 4
Joined: Wed Sep 19, 2012 8:05 am

Re: Power Supply will it work?

Thu Sep 27, 2012 7:08 am

mahjongg wrote:Hmmm. it actually states its "for a raspberry PI" :D
At 1A and 5V (I assume these are actual values not "chinese labeling") it should be fine, as long as the 5V output doesn't dip under 4.9 Volt at maximum load, and the amount of ripple on the 5V is negligible.
hi mahjongg,

i used a supply from charger port connected with usb cable.

the complete connection is raspberry pi connected to keyboard, mouse and hdmi to vga adapter.

hopwever when i started it up, the display showed nothing.

after surfing through several forums, i checked the voltage at the testing point on the board and it shows 4.4V in full load condition. does this mean the supply is not good?

and i checked the supply again with no load condition it shows 4.9V.

when the sd card is connected it dropped to 4.6V with keyboard and mouse connected,

when the hdmi to vga adapter is connected dropped to 4.4V.

can anyone tell me whats my problem? the hdmi adapter? msd card? or the supply?

User avatar
Grumpy Mike
Posts: 914
Joined: Sat Sep 10, 2011 7:49 pm
Location: Manchester (England England)
Contact: Website

Re: Power Supply will it work?

Fri Sep 28, 2012 5:19 pm

kriston wrote:I have found that the length and quality of the cable matters if you expect to plug anything into the USB ports of the Raspberry Pi. I have lots of cables but the only ones that work reliably are of the three-foot variety.
What is important is the resistance of the cable and plug. I have three leads, all about 1 ft, the resistance per connection are 0.5R 1.5R and 2.5R. So for the worst cable that is in effect 5R in series with the power supply. So the worst one would loose 3.5V if the Pi took 700mA. In fact I measured the Pi's consumption at about 300mA. Even so that is a voltage drop of 1.5V, the best cable I have only looses 0.15V.
I think there are a lot of cables around that are designed for connecting things like memory card readers where these resistances are of no consequences.

Return to “General discussion”