shadowofdarkness
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For temporary use only is 1amp fine for a Pi 2?

Wed May 13, 2015 1:12 am

I just impulse bought a second Pi 2 from a local store and have not had time to buy another 2 amp power supply and all my others are in use so until I buy another 2 amp online can the Pi 2 survive off a old 5.25v 1A power supply.

It is just the Pi2 + GPIO IR receiver. No network or USB devices. (Media on memory card)

ame
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Re: For temporary use only is 1amp fine for a Pi 2?

Wed May 13, 2015 1:14 am

Yes.


wilcal
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Re: For temporary use only is 1amp fine for a Pi 2?

Wed May 13, 2015 3:51 am

I am going to disagree somewhat. I have found with my Pi2 that under certain conditions a 1A supply is not adequate. And that with virtually no load on the USB ports. One condition is to put the Pi2 under a heavy load transferring files. With a self powered USB connected hard drive transferring 1000's of files via ftp my Pi2 froze, stopped the transfer and trashed the drive. I would recommend that only a 2A+ power supply be used with the Pi2. Once I replaced the 1A supply with a 2A supply all transfers, 10's of 1000's of them, went just fine.

ame
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Re: For temporary use only is 1amp fine for a Pi 2?

Wed May 13, 2015 3:55 am

YMMV.

drgeoff
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Re: For temporary use only is 1amp fine for a Pi 2?

Wed May 13, 2015 8:48 am

wilcal wrote:I am going to disagree somewhat. I have found with my Pi2 that under certain conditions a 1A supply is not adequate. And that with virtually no load on the USB ports. One condition is to put the Pi2 under a heavy load transferring files. With a self powered USB connected hard drive transferring 1000's of files via ftp my Pi2 froze, stopped the transfer and trashed the drive. I would recommend that only a 2A+ power supply be used with the Pi2. Once I replaced the 1A supply with a 2A supply all transfers, 10's of 1000's of them, went just fine.
Perhaps the ratings marked on the PSU only bore a passing resemblance to its true specs. It would not be the first or last time.

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MarkHaysHarris777
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Re: For temporary use only is 1amp fine for a Pi 2?

Wed May 13, 2015 9:14 am

wilcal wrote:I am going to disagree somewhat. I have found with my Pi2 that under certain conditions a 1A supply is not adequate. . . . I would recommend that only a 2A+ power supply be used with the Pi2.
I agree. (though, I have been arguing with my colleagues on this site for a couple of days now about this very topic, be careful, angels fear to tread here) :evil:

Element14 (Newark Electronics) recommends at least a 1.8A switching supply, and provides a recommended 2200 mA switching supply for sale to their Raspberry PI customers. Personally, I would not power the RPi with anything less than a 2200 mA switching supply with a relatively short cord and a good connector. Brown-outs and resets are common with RPi users because they 'cheap out' on their supply and try to go with inadequate power. There are even some folks on this site who claim to run their PI off their monitor's hdmi connector (and other ridiculous schemes). Well, its their PI, they can do with it as they please, yes?
marcus
:ugeek:

jamesh
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Re: For temporary use only is 1amp fine for a Pi 2?

Wed May 13, 2015 2:26 pm

I generally use less than 1A, but decent quality supply and good quality cables. Generally no problems at all. If using camera you might need a bit more.
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mahjongg
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Re: For temporary use only is 1amp fine for a Pi 2?

Wed May 13, 2015 3:05 pm

1.8A, is for a fully configured PI, with USB devices on all four ports, and probably also a HDMI to VGA adapter.
1A should be fine for most simple setups.
Note that the current rating on most "charger" type adapters is often not a real indication of suitableness for a PI, as a charger may drop a fraction of the 5V when loaded, while with a PI the output voltage must be regulated to 5% with all possible loads.
Also, as is said many times here, the quality (low resistance) of the microUSB cable is also essential.
Its resistance must be expressed in micro-Ohms, not fractions of an Ohm.

wilcal
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Re: For temporary use only is 1amp fine for a Pi 2?

Wed May 13, 2015 4:58 pm

The initial power supply I used on my Pi2 was the same one I used on my Pi1. It all seemed to go well but when I put the Pi2 under a heavy load, like transferring 20,000 files ftp, it would get somewhere through the process like to file 12,234 then stumble and trash the FAT table on the drive. Where it stopped was totally random. When I went to the decent 2A power supply no matter what I do it flies through the transferring process. And that's with essentially no load on the USB port. "1A should be fine for most simple setups." Yup I agree with that. But, beyond "simple" things IMO a 2A supply is recommended.

FWIW a long time ago far far away when I was in school ( 64 -> 68 ) we did a study for NASA on the milli/micro ohm resistance of common connections that were used at that time. It was all great fun and probably still relevant today. What NASA was looking for was what repeatable connection was best. Ever use a Wheatstone Bridge? You could get down into the micro-ohms even in those days. Make and remake a common military connection you'd get swings of single digit milliohms every time. Best connection???? I'll call it "smash". Take two conductors, wrap them together then smash them together with a pliers. Micro-ohm connection. Works every time.

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