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Warning about cheap leads - IriDium - 5th Nov, 2013 02:02 AM
The other day I used my USB lead from my Rpi to charge my phone at work. Unfortunately I left it at work.
I knew I had a spare lead, routed in my lead drawer and found a cheap (Ebay job) USB to micro USB lead. That will do I thought. I checked the voltage 5.15v - Ok and plugged in the Rpi.
The PSU is 5v 3.8amp and powers the RPi and the hub. The RPi connection has seen 756ma so will draw what it needs.
It worked....... almost. The ethernet sometimes worked, and then the screen started going black and then back to XBMC. The KB and mouse failed to function.
Puzzled, I plugged in a spare 1amp PSU and all worked fine.
I stripped the lead, and at 10cm it was only supplying 465ma, at it's full length - 1m - it was only drawing 265ma.
No wonder I was having problems, I'm surprised the RPi even booted.
Morel of story: Don't buy cheap, and check more than just the PSU if your RPi displays strange behaviour.
RE: Warning about cheap leads - rikardo1979 - 5th Nov, 2013 03:50 AM
I have posted few months, or more than few months and few times about this
pretty much same issues, LAN connection drops etc, etc...
RE: Warning about cheap leads - IriDium - 5th Nov, 2013 03:54 AM
Glad someone else is as ignorant as I in the RPi power issues.
A word to all gals and guys out there who answers problems.
The RPi is cheap, so users will buy cheap peripherals, leads etc.
Always ask about PSU, connectors, HUBS, leads
etc - in most cases "strange" circumstances, are not Xbian!I fell foul of it, others will also.
Thanks Rico, for making me feel normal - ish
RE: Warning about cheap leads - IriDium - 5th Nov, 2013 07:04 PM
I did a little test today, to see what amperage the RPi needs.
Below are my results. What you should gain with this, is the importance of a good power supply - 1 amp at least and a powered hub, especially if you have more than a coupe of USB devices.
The devices were attached and the system rebooted. The devices are cumulative.
At rest (Red light on) = 0.11ma
Figures in ma.
Devices attached -> Peak amperage -> At rest amperage
Nothing - 410 - 330
Wireless KB - 430 - 350
Ethernet - 510 - 450
Hub no power - 620 - 540
Hub powered - 510 - 460
Wifi – no hub - 600 - 510
Wifi – hub no power - 760 - 650
Wifi – hub powered - 510 - 460
USB speakers no power - 750 - 650
UBS speakers powered - 520 - 460
Pwd HDD no power hub - 520 - 460
Flash drive unpowered hub - 890 - 810
Re: Warning about cheap leads - rikardo1979 - 5th Nov, 2013 08:32 PM
nice one m8
I would like to see like when u stream full hd video like 20gb of size with dts sound
RE: Warning about cheap leads - IriDium - 6th Nov, 2013 12:11 AM
Didn't really make a lot of difference: 1080p 10G DTS .mkv file played over SMB.
Static 610 -> Playing video 680ma.
Interestingly, moving the mouse needed 30ma!!
Mind you, this is on Beta 2 - I wonder what it would be like on earlier releases!