radagast
Posts: 2
Joined: Fri Sep 07, 2012 11:42 am

Use a 2A power supply?

Fri Sep 07, 2012 11:52 am

I tried my RPi last night with a 1A supply but had problems with ethernet when USB devices were connected.

I have an openmoko 5v 2A powersupply but am reluctant to plug it in to RPi. Has anyone tried more than 1A?

thank you for your help,

Andrew Howlett
Owen Sound, Canada

bredman
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Joined: Tue Jan 17, 2012 2:38 pm

Re: Use a 2A power supply?

Fri Sep 07, 2012 12:20 pm

This will be OK.

You only need to worry about the minimum current, not the maximum current.

I have seen people say they use 10 Amp power supplies.

bredman
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Joined: Tue Jan 17, 2012 2:38 pm

Re: Use a 2A power supply?

Fri Sep 07, 2012 12:22 pm

There are driver problems which cause conflicts between USB and Ethernet.

Therefore you should make sure that you have loaded the latest firmware. New fixes are being released every few days.

JoeDaStudd
Posts: 274
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Re: Use a 2A power supply?

Fri Sep 07, 2012 2:47 pm

The RasPi will only draw as much current as it needs, its a case of more is better.
A lot of cheap 1a 5v psu's won't give anywhere close (enough) to the stated specs.

mdewey
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Location: UK

Re: Use a 2A power supply?

Fri Sep 07, 2012 4:58 pm

radagast wrote:I tried my RPi last night with a 1A supply but had problems with ethernet when USB devices were connected.

I have an openmoko 5v 2A powersupply but am reluctant to plug it in to RPi. Has anyone tried more than 1A?

thank you for your help,

Andrew Howlett
Owen Sound, Canada
Andrew, the things you need to worry about are
1 - is the voltage OK? Too much = magic smoke, too little = no action
2 - is there ripple on the supply?

As other have pointed out in theory if the power supply can deliver 1000000 amps the Pi should only draw what it wants from a well designed power supply although the key phrase there is well designed.

amyren
Posts: 91
Joined: Tue Jun 12, 2012 10:49 am

Re: Use a 2A power supply?

Fri Sep 07, 2012 6:42 pm

I read that the Pi also works well poweres from batteries.
If you use 1.2V rechargeble batteries 4 batteries will equal 4.8V
With non-rechargeble batteries at 1.5 you will either get 4.5V or 6V.

Anyone know the safe operating voltage range for the Pi?

toxibunny
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Re: Use a 2A power supply?

Sat Sep 08, 2012 12:20 am

I've ran mine from some sort of 2 amp apple charger. Nothing exploded. Hope this helps.
note: I may or may not know what I'm talking about...

amyren
Posts: 91
Joined: Tue Jun 12, 2012 10:49 am

Re: Use a 2A power supply?

Sat Sep 08, 2012 9:43 am

toxibunny wrote:I've ran mine from some sort of 2 amp apple charger. Nothing exploded. Hope this helps.
Thanks for the reply, but I was thinking about upper/lower voltage limits. The amps are not important here, unless its lower than the Pi requirements.
The amp rating means the maximum current the powersupply can deliver, if the amp used is to high the voltage on the powersupply will drop.

However I found the following statement on another website:
http://www.petervis.com/Raspberry_PI/Ra ... ltage.html
"The absolute minimum voltage required for the Raspberry Pi Board B is 4.8V. If the voltage is lower than this then a number of things can happen. When I experimented with my laboratory grade variable power supply, I noticed that the first main problem to occur at 4.6V was that the USB keyboard was no longer detected at boot time. At 4.4V the mouse wasn't detected at boot time. Whilst the Raspberry Pi appears to operate at lower voltages, when running video intensive applications, when the GPU is driven at maximum, the Pi can reset itself or lock-up with a blank screen."

As for maximum voltage, I still havent found a solid answer. I have read someone stating 5.2V is ok, but dont go over 5.5V. But there are also youtube videos of people booting their Pi on alkaline AAA batteries. These are 1.5V fully charges, so it equals 6V. But maybe the voltage drops below 5.5V at 500mA+.

radagast
Posts: 2
Joined: Fri Sep 07, 2012 11:42 am

Re: Use a 2A power supply?

Sat Sep 08, 2012 10:48 pm

toxibunny wrote:I've ran mine from some sort of 2 amp apple charger. Nothing exploded. Hope this helps.
Thank you, I will try the 2 amp charger next week.

jamesbond
Posts: 17
Joined: Fri Jun 21, 2013 1:13 pm

Re: Use a 2A power supply?

Sun Jul 21, 2013 3:14 am

thanks for this. i am also looking for 2 amp. power supply.

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mahjongg
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Re: Use a 2A power supply?

Sun Jul 21, 2013 10:29 am

officially the range is the same as other "5V logic", that is 5V + or - 5%, that is + or - 0.25V, so the range is from 4.75V to 5.25V

if you put 6V or more on the PI, its protection device will trigger, and short the 5V line. This happens even if you only put 6V in for a very short time, like a thousands of a second, say when you plug in a power supply that has accumulated that six volt because it didn't have any load.

When such a trigger happens the short circuit current that then will occur will be limited by the polyfuse, and therefore you need to give the polyfuse a 24H rest, before trying again. If you don't the polyfuse will simply blow again, making the recovery time even longer!

this is why its such a bad idea to plug in badly regulated cheap power supplies. Its better, if you have any doubts, to plug in the micro-USB before plugging the PSU into the wall socket. That way the PSU will have a load from the start. after you made sure the PI will boot with that PSU you can try plugging in the micro-USB port to see if it makes a difference.

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pluggy
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Re: Use a 2A power supply?

Sun Jul 21, 2013 2:47 pm

You could use a 2000 amp power supply, the Pi would still only use its approx 400mA .

Electrical theory 101.

My house has a 100A supply. Most of the time its using less than an amp or two. I couldn't afford the bills if it were using 100A (~ 25kW ) all the time.
Don't judge Linux by the Pi.......
I must not tread on too many sacred cows......

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