New RasPi Model 2 B+

W3bbo · 2015-02-11, 09:14 AM

mvallevand Wrote:I have read lots and lots of problem post on the RPi2 and many people tell you need to get a better PSU and USB cable, sorry wasn't meaning to cause any grief just passing on my real-life experience. I spent many hours on Sunday trying to get mine to not kernel panic trying all the USB power devices I have including my TV most won't send the rated 2.5 amps.

I too had similar power issues with the RPi2 and after trying several power supplies found it was indeed being caused the by very cheap USB cable I had been using.

mvallevand · 2015-02-11, 12:43 PM

W3bbo Wrote:I too had similar power issues with the RPi2 and after trying several power supplies found it was indeed being caused the by very cheap USB cable I had been using.

This weekend I am going to buy a few others to test, since I want to power of the TV too and I hope that is my problem. I only could find two around the house looking for other was part of the "hours".

stustunz Wrote:hope it works as well as b+ does on xnewa

I use the PVR Addons as a benchmark since everyone know how they run. I will be doing some x-newa tests too since it is noticeably better for me and that is what I use after testing.

Martin

gEd · 2015-02-11, 09:42 PM

mvallevand Wrote:I spent many hours on Sunday trying to get mine to not kernel panic trying all the USB power devices I have including my TV most won't send the rated 2.5 amps.
Martin

usb 2 ports only supply 500mA. You would need usb3 to provide (up to ) 5A.

mvallevand · 2015-02-11, 09:47 PM

gEd Wrote:usb 2 ports only supply 500mA. You would need usb3 to provide (up to ) 5A.

That's what I understand too which I why I say it should be factored into the cost, it's the others here that are saying otherwise. However even using my 3.1 amp wall unit, I have problems which I why I am hunting down a better cable.

Martin

pBS · 2015-03-19, 06:50 PM

power usage depends completely on what you're going to be plugging into it during use...
1 thing, look for 'regulated' power supplies,if you can... most are but better if it specifically states so.. Smile

without anything extra, a 'normal' usb port will power it fine...search web, there's power usage info that says it's about the same as rpi b+, until you plug in peripherals..

the older models had problems passing thru the 500ma per usb port for all 4 ports at once,[totalling 2000ma for all 4] so technically didn't even meet usb spec and people had all sorts of probs with power hungry usb adapters.

the pi2b seems to have fixed this, allowing full usb spec[500ma] on all 4 at once... Smile

so when looking for a power supply, add up the planned usb adapters x 500ma and add about 900/1000ma for the pi itself..
hence the 3000ma[3amp] power supply recommendation...[2000ma for 4 usb,1000ma for pi2]

but that doesn't mean you need a 3 amp power supply and fat quality cable if you're only using a usb wifi dongle that uses just 200ma..
i've been running mine off a 1000ma wall wart, with mce remote dongle and mouse/keyboard attached and it hasn't had any probs...

1 note, the thing about usb2 hard drives is they are made to use 500ma power while running [per usb spec], but also take 1000ma at startup for a short time to spin up..
[also per usb spec]

basically it pays to find out the max draw of you peripherals, and add them up so you have the needed power available to them and you won't have any probs..
[and always allow a little bit extra to allow for startup hogs]

btw, here i'm only paying $34.99US at walk in store [microcenter] for my Rpi2b, and wall warts are fairly cheap if you don't have to get a 3amp one, and they are really hard to find..

lost@c · 2015-03-19, 07:20 PM

I've now had my Pi2 for about a month and while I haven't swapped it out with the Pi B I've been testing it extensively and it works great! I'm currently powering it from the USB port on my PC which seems to cope fine and I've had no issues with it at all. I have nothing else connected to it though apart from a KVM switch which is powered from mains so I'd suspect there would be little or no load on the Pi. There has been a lot of talk about the power requirements of the Pi so I think I'll just measure it some time Smile

mvallevand · 2015-03-19, 07:29 PM

pBS Wrote:power usage depends completely on what you're going to be plugging into it during use...

My experience is that I disagree completely, my RPi2 draw mores than USB 2.0 standard 0.5 A on it's own with nothing plugged into it.

Martin

pBS · (This post was last modified: 2015-03-19, 08:24 PM by pBS.)

yes, the Rpi2 draws 900ma all by itself...[online info] so a 500ma port just won't do at all..
not every usb2 port limits their ports to 500ma like spec says, pretty sure that's only a minimum requirement and usually safe to provide 1000ma. from a usb port. [and many do]

notice i said, "hence the 3000ma[3amp] power supply recommendation...[2000ma for 4 usb,1000ma for pi2]"
i guess i can make clearer that it's 2000ma for the usb ports alone, and add another 1000ma for the Rpi2b cpu..
so the minimum is 1000ma with nothing plugged in... Big Grin

but to correct that, the total power available to the usb ports is actually only 1.2amp, so you could use only a couple[2] of full usb spec devices..[500ma x 2 = 1000ma, w 200ma left]

http://raspi.tv/2015/raspberry-pi2-power...easurement

stustunz · 2015-05-17, 11:53 PM

If you get flashing rainbow box (top right corner) it running out of juice you need to change power supply or cable.

martint123 · 2015-05-18, 09:28 AM

Been running a week now with it plugged into the TV USB port and seems to be working ok so far. Only usb devices are keyboard and wireless dongles.
TV USB connector says 5V 1A.