Under-voltage ?

[valx76]

Hi,

first, I'm sorry if my question is not in the right place, I'm not sure about it..

I'm using a RPi model B / Rev1 with official RPi camera and TP-LINK WN725N USB WiFi adapter directly connected to the Pi.
I'm using an external battery which gives 1A or 2.1A. Actually I'm using 1A (but if you tell me that's better to use the 2.1A, I can).
It is running GStreamer to stream the camera (to give you an idea about the network use).

The problem is that the Pi crashes randomly.. It looks like it's the WiFi USB because its light disappear.
I read some network related problems in the wiki, apply the fixes but it continues..

I also read that could be the polyfuse ?
If I'm using a newer Pi (512MB one) could it solve the problem ?
Or should I really buy a powered usb hub ?


Best regards!

[RaTTuS]

Model B or B+ [2 or 4 USB ports]
measure the power on the test points
make sure the image is up to date
sudo apt-get update && sudo apt-get upgrade -y
sudo rpi-update

[valx76]

Hi RaTTuS,

I have the "0002" revision, model B, with 256MB (2 USB ports).
The Pi kernel + apps are less than 2 months old so I don't think that could be the problem (3.12.24+ #694)..

I also tried with another battery and that is the same..

I can also say that actually, if I'm plugging the USB WiFi and Ethernet at the same time, the Pi crash 90% of the time.

[RaTTuS]

you are going to be current limited ,
measure the power at TP1 TP2
bypass the internal fuse
or get a good quality 2A or better powered HUB and power the RPi from that as well as the things plugged into it

[valx76]

Btw, if I'm using (I can have one for free) a 512MB model, do you think that could solve it the problem ?
Instead of soldering on the board to bypass fuse..

About the battery, that's the best I saw, a TeckNet® PowerBank 15000mAh (and I have also a TeckNet® PowerBank 7000mAh).

About the measurement, I have 4.4V (TP1-TP2) with USB WiFi, 2 wires in GPIO, and the RPiCam..
So that's a battery problem ? I tried with another USB cables so... :/

EDIT: I tried with a new USB adapter (the official LG Nexus 5 one, with 5V/1.3A), I don't have better results, so that can be a problem with my RPi..

EDIT2 : Some more tests.

• Polyfuse test (nothing connected) : 5.10V
  TP1/TP2 test without anything connected : 5.10V
  TP1/TP2 test with SD only : 4.70V

[RaTTuS]

the USB lead may be dropping too much voltage try a fatter micro USB lead
4.75V is the comfortable minimum [5V +/- 5%]
but may work [if you are not using the USB then my 0002 is happy with 3.6V [well just about]
but high drain things like wifi will possibly drop the voltage too much for the SOC to run reliably,

as you want to run this off a battery back then it may be worth powering a USB hub from the pack and using that to power the RPi and your peripherals YMMV

[valx76]

Thanks for your answers RaTTuS, I'll try to find a good little hub for my project !
My battery should be able to power the Pi and the hub at the same time or use a second battery for the hub (I really need wireless things, because that's a robot ).

[RaTTuS]

yeah a Model B+ has better power capabilities than a model B [a model A would also be better but you only get 1 USB]

it should run it OK..

[valx76]

I tested with a more recent model B (512 Mb without polyfuse) and that's great !
Without USB hub I have 4.95V with Camera + USB WiFi !!