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Help me feed a Power Hungry RPi

dzed

I've just completed building a kit  with a 7" touch screen and  RPi 3B.

 

The  tutorial I found  presented   3 options for  powering the  kit..

 

A.  Cable from the USB power out on the display board to the Micro USB power in.    Id rather NOT make holes in the case supplied to enable  this.

 

B . GPIO power bridge to the display board via  jumpers  ( The option I selected)

 

C. 2 Micro usb power connectors,  1 to the display board and  1 to the  RPi...  

 

After assembly and some use I've noticed the  "lightning flash" on the upper right,  which I understand indicates a low power condition.

I'm using the "standard" 5V/ 2.5A RPi 3B wall plug..   and the unit  "works"   with power applied to either of the inputs...

 

My questions.... 

    

     What am I really  risking  running the unit  in an underpowered condition???   Is it just throttling the  CPU back?

 

     Is it safe to apply power to both USB inputs  with the GPIO powers jumpers in place?

 

     Are there any "known hacks" to reduce the power consumption of the display to minimize the impact?

  • 0

    Hi,

     

    That's not normal if the official Pi 7" touchscreen and official power supply (with permanently wired cable with micro USB connector) is used.

    Depending on the work load, the Pi 3 can consume a lot of power (up to 1.4A at 5V), but you'd soon know if you were, because the CPU would get extremely hot, too hot to touch.

    If you wish to test with a supply powering the display separately, then the power jumpers connected to the 40-way connector should be disconnected.

    In the underpowered condition there could be a risk of corruption or any USB attached devices not operating correctly.

  • 0

    I agree with and with the official power unit something sounds not normal. If this can be helpful I have used continuously for some days a PI3b + LCD 7 inches, using ther ethernet cable connected to a computer. The CPU was almost stressed as I was testing and developing, the LCD never was in standby mode and in addition I was using through the local LAN the PI from the Display itself (testing graphic UI), a VNC connection and the ssh shell so as a matter of fact there was three users connected at the same time to the Pi. Then the PI /home/pi folder was shared with the PC and remotely mounted. With this scenario I had no problem in powering the system and I have also tried to power the system with a battery unit supply of 2.4 A (7600 mA/h) and it worked perfectly in test for about 6 hours.

     

    Enrico

  • 0

    I have the official 7" Touch Screen & RPi 3B in an SmartiPi Touch Enclosure. I soldered the Jumpers (from TFT Screen [Excluding (Red) +5V]) to the RPi 3B Bottom Side of GPIO Pins. Have not seen Heating Problems w/ this Combo. Was able to drive this off a 2000mAh Battery Bank (w/ WiFi Working, USB KeyBd, USB Mouse). The SmartiPi Case came w/ a Y-cable (female micro-USB B TO dual male micro-USB  B connectors). Much  Like  DO's Option C. Works for Me.

    USCDADNYC (NY NY USA)

  • 0 in reply to balearicdynamics

    EM wrote>>...[I] power[ed] the system [RPi-TFT screen] with a battery unit supply of 2.4 A (7600 mA/h)...

    USCDADNYC Question>> Is there a (mathematical) relationship between 2.4A and 7600 mA/h?

    USCDADNYC (NY NY USA)

  • 0 in reply to shabaz

    Thanks for the feedback (everyone)...

     

    I've reflashed the  SDC with a copy of Ubuntu Mate (16.10)  and used the display slider to reduce the screen brightness to ~= 30%.

     

    I still get the power indicator briefly at boot time,  but only  very  occasionally  after that.    I've run the RPi the better part of a day, and the  case ventilation seems to be adequate to keep the  CPU/GPU temperature at reasonable ( Warm to the touch) levels, indicating it is probably the display.    I'd hoped to minimize the number of cables external to the case, but changing the battery power unit to one with 2USB outlets is a viable design change..   I will make sure to remove the GPIO power jumpers before testing that out... 

     

    It's a little concerning that the panel seems to be  "abnormally thirsty", but I'm still impressed/pleased with the overall performance.