Dagasus
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Power adapter with 5v 4amp pi3 B+

Fri Sep 07, 2018 11:41 am

Pi3 B+ overclocked cpu and gpu, hard drive and two fans in a nintendo 8bit case.
Would a 4amps power adapter burn the mothercard?

texy
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Re: Power adapter with 5v 4amp pi3 B+

Fri Sep 07, 2018 12:22 pm

Hi,
no - you can 'give' it 100 amps and it will only take the current it needs. Voltage is another matter however.
Texy
Various male/female 40- and 26-way GPIO header for sale here ( IDEAL FOR YOUR PiZero ):
https://www.raspberrypi.org/forums/viewtopic.php?f=93&t=147682#p971555

alphanumeric
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Re: Power adapter with 5v 4amp pi3 B+

Sat Sep 08, 2018 9:46 pm

What he said. I have one Pi running off of a 5V 10A power supply and another running off of a 5V 4A power supply. They only draw what current they need.
Being able to supply more than what is needed is not an issue.
Not being able to supply what is needed is an issue.

drgeoff
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Re: Power adapter with 5v 4amp pi3 B+

Sat Sep 08, 2018 11:33 pm

Dagasus wrote:
Fri Sep 07, 2018 11:41 am
Pi3 B+ overclocked cpu and gpu, hard drive and two fans in a nintendo 8bit case.
Would a 4amps power adapter burn the mothercard?
The electricity supply to your house can provide tens of Amperes yet even if the only thing switched on is a 5 Watt LED lamp (0.05 Amperes in US or 0.025 Amperes in Europe) it doesn't get "burned".

k-pi
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Re: Power adapter with 5v 4amp pi3 B+

Sun Sep 09, 2018 9:57 am

Slightly off topic, but could be useful info....

If I have a HDD/SSD connected via the USB sockets, & there isn't enough power for it to boot, would increasing the Amps of the power supply help to get it to work?

mattmiller
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Re: Power adapter with 5v 4amp pi3 B+

Sun Sep 09, 2018 10:05 am

You've got 2 issues

Yes - generally if you add devices that consume extra current than your present power supply can provide then you need to get yourself another power supply that can supply it

On top of that, The USB ports are only rated to supply a total of 1.2amps (I might be wrong on this exact value but I think its right)

So, if your USB device needs more than that amount, you really need to look at providing it with its own separate power

k-pi
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Re: Power adapter with 5v 4amp pi3 B+

Sun Sep 09, 2018 10:38 am

Thanks for your reply - yes, I am indeed using external power supplies with them right now, (but was wondering if the under power was a lack of amps).

I'm using the official 2.5A power supply, but it isn't enough for my disks, so I'll see if I can find one of higher amperage to try out. 8-)

Brandon92
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Re: Power adapter with 5v 4amp pi3 B+

Sun Sep 09, 2018 10:57 am

k-pi wrote:
Sun Sep 09, 2018 10:38 am
Thanks for your reply - yes, I am indeed using external power supplies with them right now, (but was wondering if the under power was a lack of amps).
How much power and voltage is that power supply delivering for your external HDD

alphanumeric
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Re: Power adapter with 5v 4amp pi3 B+

Sun Sep 09, 2018 11:27 am

I believe all but the Pi Zero have a poly fuse that will limit the current available to peripherals.
https://www.raspberrypi.org/help/faqs/#topPower
Pi 3B is limited to 1.2A combined on the 4 USB ports.

LTolledo
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Re: Power adapter with 5v 4amp pi3 B+

Sun Sep 09, 2018 12:36 pm

k-pi wrote:
Sun Sep 09, 2018 9:57 am
Slightly off topic, but could be useful info....

If I have a HDD/SSD connected via the USB sockets, & there isn't enough power for it to boot, would increasing the Amps of the power supply help to get it to work?
Got my interest piqued so gave it a try
Setup are as follows:
  1. Raspberry Pi 3 Model B+
  2. 5v 3.0 amp PSU (non RPF specified model, but widely available from my source)
  3. Flirc gen2 case (probably no bearing on this test)
  4. 7" HDMI monitor (of course connected via HDMI cable)
  5. 2.4GHz Wireless Mouse USB dongle (USB port top right)
  6. 2.4GHz Wireless Keyboard USB dongle (USB port bottom right)
  7. Sandisk 240GB SSD with Eluteng SATA to USB3.0 adapter cable (USB port top left), as USB boot device, Raspbian Stretch with Desktop
  8. Marshal 1TB 2.5" HDD with Inateck SATA to USB3.0 adaptor cable (USB port bottom left), USB boot device for another RPi3B+, but connected as secondary HDD for this test.
  9. WiFi connection to the network
As you can see from the list above, all USB ports were used.

Powered up the setup hoping for it to fail.....(expecting just the rainbow screen or none at all)
Undervoltage warning did appeared after the 4 raspberries appeared....
But lo! it booted... from the SSD!
After boot up I checked if the 2nd HDD was mounted, it did!

Here are some command outputs from the test

Code: Select all

pi@RasPi3B4SSD240G:~ $ lsusb
Bus 001 Device 004: ID 046d:c52f Logitech, Inc. Unifying Receiver
Bus 001 Device 005: ID 062a:4c01 Creative Labs 
Bus 001 Device 008: ID 174c:55aa ASMedia Technology Inc. ASM1051E SATA 6Gb/s bridge, ASM1053E SATA 6Gb/s bridge, ASM1153 SATA 3Gb/s bridge
Bus 001 Device 007: ID 174c:55aa ASMedia Technology Inc. ASM1051E SATA 6Gb/s bridge, ASM1053E SATA 6Gb/s bridge, ASM1153 SATA 3Gb/s bridge
Bus 001 Device 006: ID 0424:7800 Standard Microsystems Corp. 
Bus 001 Device 003: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 002: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Code: Select all

pi@RasPi3B4SSD240G:~ $ lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 223.6G  0 disk 
├─sda1   8:1    0  43.1M  0 part /boot
└─sda2   8:2    0 223.5G  0 part /
sdb      8:16   0 931.5G  0 disk 
├─sdb1   8:17   0  43.2M  0 part /media/pi/boot
└─sdb2   8:18   0 931.5G  0 part /media/pi/rootfs

Code: Select all

pi@RasPi3B4SSD240G:~ $ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/root       221G  6.3G  205G   3% /
devtmpfs        370M     0  370M   0% /dev
tmpfs           375M     0  375M   0% /dev/shm
tmpfs           375M   11M  365M   3% /run
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           375M     0  375M   0% /sys/fs/cgroup
/dev/sda1        43M   22M   21M  52% /boot
tmpfs            75M     0   75M   0% /run/user/1000
/dev/sdb2       917G  3.6G  877G   1% /media/pi/rootfs
/dev/sdb1        43M   22M   21M  52% /media/pi/boot
no other warnings once in desktop mode....

rebooted and connected the LAN cable (so I'll have both Ethernet and WiFi enabled)
by this time, except for the TRRS jack, all ports were used (4 x USB, 1 x Ethernet, HDMI) + WiFi
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

k-pi
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Re: Power adapter with 5v 4amp pi3 B+

Sun Sep 09, 2018 6:33 pm

Interesting test, looks like I will have to find myself a higher amperage power supply - thanks for posting your results. :)

Apologies to the OP for taking your thread a little off topic. 8-)

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Imperf3kt
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Re: Power adapter with 5v 4amp pi3 B+

Sun Sep 09, 2018 9:31 pm

You will need an *external* supply, one powering a USB hub.
The reason one HDD and one SSD booted is because SSDs have no moving parts and draw a fraction of the energy a spinning disc of rusty glass uses.
A HDD can use up to ~1A just by itself when spinning up, attach two of them and thats 2A, but the Pi USB ports can only allow a maximum of 1.2A regardless of what power supply you use.
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