Jump to content


Photo

RaspberryPi3 Power droop fix.


  • Please log in to reply
17 replies to this topic

#1 Master_Scythe

Master_Scythe

    Titan

  • Hero
  • 20,211 posts
  • Location:QLD

Posted 23 May 2017 - 04:33 PM

OK, so the newest RaspberryPi3 needs 2.5A from a USB port, and is rated up to 5.25V.

I can easily get some 12V supplies, then run them to an RC UBEC 5.1V by Turnigy, they'll do 3A easily.

However, I've been using my Pi on a 2.3A supply for a few days now, with no lockups.

I do however, get the little lightning bolt at the top of the screen warning me my supply is drooping below 4.5V

This, however, is NOT constant, it only happens while in the Kodi menu, when playing video, it never droops the voltage.

 

So I just had an idea......

 

You can power a RaspberryPi via it's "Pins" (people call them GPIO, but they're the 6 that aren't).

If I was to whack a super-capacitor on pins 2 and 6, the power and ground pins, this might eliminate the momentary sag.

 

Experimenting is what these little PC's are all about, so I'm going to try it.

But any thoughts?

 

I can get a 1F 5.5VDC Super Capacitor for $6.

I might try this trick with a NORMAL capacitor first and see if that's enough.


Wherever you go in life, watch out for Scythe, the tackling IT support guy.

"I don't care what race you are, not one f*cking bit, if you want to be seen as a good people, you go in there and you f*ck up the people who (unofficially) represent you in a negative light!"


#2 Master_Scythe

Master_Scythe

    Titan

  • Hero
  • 20,211 posts
  • Location:QLD

Posted 23 May 2017 - 04:53 PM

Bumpin it from the spammers.


Wherever you go in life, watch out for Scythe, the tackling IT support guy.

"I don't care what race you are, not one f*cking bit, if you want to be seen as a good people, you go in there and you f*ck up the people who (unofficially) represent you in a negative light!"


#3 Rybags

Rybags

    Immortal

  • Super Hero
  • 35,097 posts

Posted 23 May 2017 - 05:38 PM

PITA requirement - I've lost count how many USB warts I've got but probably over 10.  Most are packed away because they're piddly < 1.5 Amp jobs.

I've got 2 x 2 Amp ones, one came with my Nexus 7 and the other one is a junk Chinee job that claims 2 Amps but is probably closer to 1.5 and has one of those annoying international adaptors that doesn't stay attached.

 

Remember those early 2.5" drives where you had to use a Y-cable to give it enough juice?  Maybe something like that.  Also, some of the 2 outlet USB wallwarts give a combined current around what you'd need.



#4 Gas Lee

Gas Lee

    Primarch

  • Atomican
  • 1,801 posts
  • Location:Sierra Madre, CA

Posted 23 May 2017 - 11:21 PM

My Pi3 runs pretty happily from a 2a charger, but it's an above average one meant to charge a HP Stream 8.

 

Just remember that if you're applying power via the pins in the gpio block you're avoiding the polyfuse so it will let the magic smoke out if you get it wrong.


-What we know is almost nothing at all-

#5 Master_Scythe

Master_Scythe

    Titan

  • Hero
  • 20,211 posts
  • Location:QLD

Posted 24 May 2017 - 08:46 AM

My Pi3 runs pretty happily from a 2a charger, but it's an above average one meant to charge a HP Stream 8.

 

Just remember that if you're applying power via the pins in the gpio block you're avoiding the polyfuse so it will let the magic smoke out if you get it wrong.

 

That's why I was going to use a supercap.

I'm installing a Surge Tank, not a Fuel pump ;)

 

The charger I'm using is a 2.4A per port, 3.6A Max Ikea charger.

bigclive on youtube tore one down and its EXTREMELY well built and specced well below it's ability.

 

I just can't find anything else thats 2.5A or more, besides using an RC UBEC, and supplying it with a laptop charger (19.5v)


Wherever you go in life, watch out for Scythe, the tackling IT support guy.

"I don't care what race you are, not one f*cking bit, if you want to be seen as a good people, you go in there and you f*ck up the people who (unofficially) represent you in a negative light!"


#6 Gas Lee

Gas Lee

    Primarch

  • Atomican
  • 1,801 posts
  • Location:Sierra Madre, CA

Posted 24 May 2017 - 10:06 PM

This is one of my toys:

 

http://imgur.com/WXyjL5T

 

Pi3 sitting at the top, not actually plugged in, mostly runs Retropi

Pi2 next, connected to the SDR at the top of the stack tracking aircraft via PiAware / Flightaware

Arduino Yun handling routing / firewall duties for the stack, stack has no physical network connection, it all routes via the Arduino wifi.

PiB+ being my linux terminal server / IRC lurker

5 port switch

5 port usb charger from Bunnings.

 

The Bunnings charger supposedly does 7a across 5 ports, I need to throw my clamp meter at it to see what the actual consumption of the stack is, but it's running everything (switch included) and not getting warm so I'm fairly pleased with that

 

I'm looking for a SBC to live on the shelf the Pi3 is sitting on that isn't a Pi, just for interest sake, maybe something powerful enough to give me a remote gui or something with sata to be a file server for the stack.


-What we know is almost nothing at all-

#7 Master_Scythe

Master_Scythe

    Titan

  • Hero
  • 20,211 posts
  • Location:QLD

Posted 25 May 2017 - 08:46 AM

This is one of my toys:

 

http://imgur.com/WXyjL5T

 

Pi3 sitting at the top, not actually plugged in, mostly runs Retropi

Pi2 next, connected to the SDR at the top of the stack tracking aircraft via PiAware / Flightaware

Arduino Yun handling routing / firewall duties for the stack, stack has no physical network connection, it all routes via the Arduino wifi.

PiB+ being my linux terminal server / IRC lurker

5 port switch

5 port usb charger from Bunnings.

 

The Bunnings charger supposedly does 7a across 5 ports, I need to throw my clamp meter at it to see what the actual consumption of the stack is, but it's running everything (switch included) and not getting warm so I'm fairly pleased with that

 

I'm looking for a SBC to live on the shelf the Pi3 is sitting on that isn't a Pi, just for interest sake, maybe something powerful enough to give me a remote gui or something with sata to be a file server for the stack.

 

Intel Edison?

 

BTW if you ever decide to upgrade that PiB+ I'm always looking for cheap 1st gen Pi's.

I make 2D emulator boxes out of them :)


Wherever you go in life, watch out for Scythe, the tackling IT support guy.

"I don't care what race you are, not one f*cking bit, if you want to be seen as a good people, you go in there and you f*ck up the people who (unofficially) represent you in a negative light!"


#8 Gas Lee

Gas Lee

    Primarch

  • Atomican
  • 1,801 posts
  • Location:Sierra Madre, CA

Posted 29 May 2017 - 08:25 PM

So, my clamp meter wouldn't read the current consumption of my SBC stack on the DC side (it's a 400 amp unit, meant for cars), but I've now plugged it into my Killawatt and can report that the entire stack consumes 20 watts on the AC side.

 

If we totally ignore the efficiency of the USB power supply that is 4 amps being consumed by 3 single board computers, a network switch and a software defined radio (SDR I know consumes about 600ma/3w)

 

This makes me wonder what your pi is pulling to make your supply droop on the voltage.


-What we know is almost nothing at all-

#9 Master_Scythe

Master_Scythe

    Titan

  • Hero
  • 20,211 posts
  • Location:QLD

Posted 30 May 2017 - 08:38 AM


This makes me wonder what your pi is pulling to make your supply droop on the voltage.

 

Dunno.

It seems to be when showing VSYNC'd content.

 

It's a 2.4A charger with a 10cm "good quality" cable. So it's likely getting the whole lump of it.

It just needs 2.5A apparently.

 

These are the USB adaptors I use.

I'm only using one port :)

Rated at 2.4A per port, 3.5A overall.

 


Edited by Master_Scythe, 30 May 2017 - 08:39 AM.

Wherever you go in life, watch out for Scythe, the tackling IT support guy.

"I don't care what race you are, not one f*cking bit, if you want to be seen as a good people, you go in there and you f*ck up the people who (unofficially) represent you in a negative light!"


#10 Gas Lee

Gas Lee

    Primarch

  • Atomican
  • 1,801 posts
  • Location:Sierra Madre, CA

Posted 31 May 2017 - 11:01 AM

Have you thrown a multimeter across the 5v pins in the GPIO block?

 

Just wondering if the full juice is making it to the pi, maybe this pi has a shady polyfuse / microusb.


-What we know is almost nothing at all-

#11 Rybags

Rybags

    Immortal

  • Super Hero
  • 35,097 posts

Posted 31 May 2017 - 11:32 AM

Plenty of chargers will drop voltage even when under their rated load.

 

That's probably the problem - a "charger" has the advantage that the battery can make up any shortfall in voltage and current so you don't notice on a tablet or phone, other than those times where the battery% still goes down during heavy use.  Where a "power supply" will in theory always be able to cover the peak demand.



#12 Master_Scythe

Master_Scythe

    Titan

  • Hero
  • 20,211 posts
  • Location:QLD

Posted 31 May 2017 - 11:36 AM

That's where I'll probably end up with one of these.

 

22494.jpg

 

5.1V @ 3A (apparently 5A spike). I'll use an old 19v Laptop charger as input I guess.


Edited by Master_Scythe, 31 May 2017 - 11:36 AM.

Wherever you go in life, watch out for Scythe, the tackling IT support guy.

"I don't care what race you are, not one f*cking bit, if you want to be seen as a good people, you go in there and you f*ck up the people who (unofficially) represent you in a negative light!"


#13 Rybags

Rybags

    Immortal

  • Super Hero
  • 35,097 posts

Posted 31 May 2017 - 11:44 AM

Or router PS?  I've got one that's 2A, but most seem to be 1-1.5

 

Does it give output current as you'd expect based on the wattage capability of the input or is the current same as the input - e.g. can it turn 12V DC @ 1A into 5V DC @ 2.4A ?


Edited by Rybags, 31 May 2017 - 11:44 AM.


#14 Master_Scythe

Master_Scythe

    Titan

  • Hero
  • 20,211 posts
  • Location:QLD

Posted 31 May 2017 - 02:06 PM

Or router PS?  I've got one that's 2A, but most seem to be 1-1.5

 

Does it give output current as you'd expect based on the wattage capability of the input or is the current same as the input - e.g. can it turn 12V DC @ 1A into 5V DC @ 2.4A ?

 

Nah, most UBEC's are less than 50% efficient, unless its a switch mode.

 

Router power supply?

Do they come in MicroUSB?


Wherever you go in life, watch out for Scythe, the tackling IT support guy.

"I don't care what race you are, not one f*cking bit, if you want to be seen as a good people, you go in there and you f*ck up the people who (unofficially) represent you in a negative light!"


#15 Gas Lee

Gas Lee

    Primarch

  • Atomican
  • 1,801 posts
  • Location:Sierra Madre, CA

Posted 31 May 2017 - 02:21 PM

The UBECs aren't 100% efficient, but they do a conversion on the input wattage to get the output wattage so 12v1a will turn into more like 5v2.2a.

 

I've been planning an upgrade of my Pi stack to eliminate the USB power supply and a couple of those UBECs looks like the way to do it, I'd like to bring the stack input voltage up to 12ish with the end goal of being able to run the stack off a solar panel in the back yard (charging something like an old car battery) so the input flexibility of the UBEC is going to be super handy.

 

 

(edit: I've been looking at switch mode UBECs)


Edited by Gas Lee, 31 May 2017 - 02:22 PM.

-What we know is almost nothing at all-

#16 Rybags

Rybags

    Immortal

  • Super Hero
  • 35,097 posts

Posted 31 May 2017 - 02:37 PM

The 3 routers I have here are all 12V DC and fairly sure all use the "standard" barrel type connector.

I imagine most routers would use a well over specced PS given that they can be powered on for years at a time.



#17 Master_Scythe

Master_Scythe

    Titan

  • Hero
  • 20,211 posts
  • Location:QLD

Posted 31 May 2017 - 02:42 PM

The UBECs aren't 100% efficient, but they do a conversion on the input wattage to get the output wattage so 12v1a will turn into more like 5v2.2a.

 

I've been planning an upgrade of my Pi stack to eliminate the USB power supply and a couple of those UBECs looks like the way to do it, I'd like to bring the stack input voltage up to 12ish with the end goal of being able to run the stack off a solar panel in the back yard (charging something like an old car battery) so the input flexibility of the UBEC is going to be super handy.

 

 

(edit: I've been looking at switch mode UBECs)

 

I'm not sure if those Turnigy ones are switch mode.

However they're the only ones to offer 5.1V as opposed to 5V.

 

5.1V is much preferable for the rPi's.

Reports of better overclocks and card stability 'over 5v'. And still within the 5.2*V spec


Wherever you go in life, watch out for Scythe, the tackling IT support guy.

"I don't care what race you are, not one f*cking bit, if you want to be seen as a good people, you go in there and you f*ck up the people who (unofficially) represent you in a negative light!"


#18 Gas Lee

Gas Lee

    Primarch

  • Atomican
  • 1,801 posts
  • Location:Sierra Madre, CA

Posted 31 May 2017 - 04:19 PM

I've got 4.94v at the gpio header on both of the Pi and 4.8v(!) at the headers on the arduino.

 

They don't seem to care, none are what I would call heavily loaded and nothing is overclocked, but this is the other part of why I'd like to move away from usb power supply.


-What we know is almost nothing at all-




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users