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Power requirements of the Pi
The Foundation has recommendations for various models which range from 700mA to 3.0A.
These are quite generous, and all models will operate on a decent 1A supply - I can run my Pi3 with WiFi/keyboard/mouse/HDMI from an Apple 5W supply. Extra current may be required by USB peripherals and the recommended supplies make allowance ...
43
It seems that the only concern is that your power supply, if it's not a decent, reliable supply capable of 2A+ of clean output power, might not be able to power the Pi sufficiently, resulting in crashes or frequent rainbows.
See, specifically:
All that max_usb_current=1 does is to set GPIO38 high, which in turn turns on a FET, which connects a second 39K ...
25
Everything for sale is built to a price.
Tha manufacturer wants to make a profit.
There is no need for many USB cables to carry more than a fraction of an amp so they would be built with thin wire. Thin wire is cheaper and lighter than slightly thicker wire. All other things being equal thinner wire has a higher resistance and can carry less current and ...
23
You can use my tool uhubctl, it supports Raspberry Pi models B+, 2B, 3B, 3B+ and 4B - these models have hardware ability to turn USB power off and on.
Use it like this:
Turn off power to all USB ports (must use port 2):
sudo uhubctl -l 1-1 -p 2 -a 0
Turn on power to all USB ports (must use port 2):
sudo uhubctl -l 1-1 -p 2 -a 1
Turn off power to Wifi+...
17
Not without voiding your warranty. An RPi4 can deliver a maximum of 1.2 A to all the USB ports together. This is done to protect the USB-C connector which is rated for 3A maximum.
The disks you have in mind consume up to 1 A each.
Without touching to the Pi, you'll need to use a powered USB hub or a bigger-capacity single disk. If you don't care about the ...
15
I am running a Raspberry Pi2 with a 2TB Western Digital element hard disk mounted as root disk (apm set to 254 - effectively disabling standby) via a Y-connector.
Using a USB VA meter (eBay link - LCD USB Charger Current Voltage Detector Tester Monitor Meter For Phone Tablet) I measured (with both the USB HDD and Raspberry Pi2) 5V and about 0.7A.
Measured ...
15
These type of enclosed hard drives conform to the USB specification 2.0 specification, even though it's USB 3.0 it must be able to fall-back. USB 3.0 provides lots more power, but since it falls back it must conform to the USB 2.0 500 mA maximum current. The hard drive itself might use more power, but the built-in electronics will detect when to use ...
15
Cables do make a difference once you start to draw hundreds of mA or several A.
You can often tell how much current a cable can carry simply by its looks. Anything thick and stiff is good, thin and overly flexible may cause trouble. Check out these pictures to see what I'm talking about:
VS
Cable length also has a similar effect: Shorter cables are much ...
12
Use a PoE Hat:
Third-party USB-C charging devices can be cheaply wired, potentially destroying connected devices as well as starting fires. A safer alternative is to power your Pi using PoE which beyond reducing these risks, offer additional benefits:
Benefits:
Using a PoE Hat is easy to setup and enables you to:
Emplace a Pi at a much greater distance from ...
10
This qualifies under category circuit rework.
The "best" solution, if the pads are still usable, is to purchase the replacement part and re-attach it. The part is about $1 USD but this does not include shipping Vendor Link (Part Number Found in Schematic)
It is generally a good idea to repair something to its original state. Most things can be repaired if ...
9
The best option is a good quality power supply, as cheap brands may say they are rated at 2.4 amps, when they don't actually supply that much. Based on the numerous bad experiences i've had with 3rd party chargers, i'd highly recommend buying the official one from the foundation!
Whether that is adequate for the hard drive is another question. I haven't ...
8
There are a few factors to consider here:
The power input to your Pi is probably through a wall adapter or PSU. You should check the rating of the adapter/PSU. If it is in the range of 1.5A to 2A, then your problem is partially solved.
Next in play, is the polyfuse and regulator on board the Pi. As per specifications on Adafruit, the B+ can handle upto 2A ...
8
The Pi 2 should be able to run that HDD directly. However, by default the power to USB is limited to 600 mA, which is not enough (I've had the same issue with an external drive).
To make 1.2 A available -- which is fine if your power supply is up to it -- add the following to /boot/config.txt:
max_usb_current=1
And reboot. Your HDD should now light up ...
8
Popular things like the Raspberry Pi surround themselves with Urban Myths.
One such is the USB cable Myth.
That is not to say there is some grain of truth, there usually is, but people jump to conclusions.
USB2 is specified to supply 500mA max.
USB power is 5V ±0.25V
To remain in spec there should be less than 0.25V drop which corresponds to loop ...
8
According to the Raspberry Pi FAQ on Power requirements ( which can be found here --> https://www.raspberrypi.org/help/faqs/#powerReqs ):
Maximum draw from USB = 1.2A
Recommended Power Source = 2.5A
Now, according to USB specifications power output for USB works like this:
USB 1.x and 2.0 specifications provide a 5 V supply on a single wire
to ...
8
The spec specifically states that:
A good quality 2.5A power supply can be used if downstream USB peripherals consume less than 500mA in total.
Using a 2.4A power supply with the Pi 4 and a 2.5" HDD is going to be borderline assuming a typical power rating of the 2.5" drive of about 1.8W to 2.7W (see here). From the above statement - after all it really ...
8
The Raspberry Pi 4 spec recommends a 3 A supply (15 W), with a minimum current of 2.5 A if downstream USB peripherals consume less than 500 mA in total.
Furthermore the MagPi benchmarks a power draw under load of 7.6 W "running a CPU-intensive benchmark while an HDMI display and a USB keyboard and mouse are connected" (note that they do not state the use ...
7
Power Consumption Benchmarks
The instrument used to measure power consumption with the Dramble and individual Raspberry Pis: PowerJive USB Power Meter
In all measurement cases, nothing is plugged into USB ports (unless otherwise noted).
The measurement was performed using inline USB voltage tester, which consumes power for measuring and hence there may ...
7
From my personal experience, WD Blue HDD (WD10JPVT/WD10JPVX with 0.55A average current) might work more or less reliably (== require about 1 reboot / month) connected directly to RPi without any powered hub.
Your particular HDD requires much higher currents, so it's very unlikely you'll be able to do anything reasonable without an external power.
7
It is acceptable to power the Pi via the GPIO pins, however to comply with the guidelines you should implement a power isolation circuit (as in the B+ or Pi 2 schematic). Direct connection bypasses the overvoltage protection but is acceptable with a well regulated supply (which most mobile chargers aren't).
7
Question
For connecting two USB SSD/HDDs, does an Rpi USB Hub need any external power?
Short Answer
Update for Rpi4B buster 2020apr16
Soon after my 2019jul answer below, I upgraded from Rpi3B+ to Rpi4B, with 1/2/4G RAM, and successive releases of buster (now Release 2020feb). I am happy to update my SSD report that so far as good.
I measured the ...
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This answer is no longer valid!
It was related to original Raspberry Pi model A/B, with USB 2.0 and 100 mbit LAN. Raspberry Pi model 4B has USB 3.0 controller and 1 gbit LAN, so previous limitations no longer apply.
Original answer from 2013:
Let's do the math. Uncompressed 1080p RGB frame is about ~6MB big. USB 2.0 can transfer up to 60 MB/s but it ...
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Yes, I have done this sort of thing several times and I am no electronics expert. You have to be quite sure that you have the polarity right and that everything is fully insulated.
I buy two heat shrink tubes, one larger and one smaller. Then I cut off both barrel connectors making sure that the one you intend to use has enough wire to work with.
Now ...
6
Yes. SD cards are volatile, and, as all memory does, will deteriorate over time. Nothing you really can do about it besides not use the device. This is because of the need to be small, the technology isn't quite as long lasting as a Hard Drive or SSD/RAM. Basically, all memory will deteriorate eventually, it just depends on the use it is put through.
More ...
6
Use an USB hub that has a power supply?
You should check how much power your HDD needs and how much the USB hub can deliver.
Maybe this question can help: link
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No.
The micro USB ports are hard wired.
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You SHOULD be able to power a USB HDD from the Pi3B+ as the USB ports can supply 1.2A.
HOWEVER, I and others have found that this is often unreliable - this seems to be due to transient voltage drop when the disk starts.
I have conducted a number of tests, and often the voltage on the USB ports is low. (I an using a rock solid external 5V power supply with ...
6
The Pi3B+ can supply up to 1.2A total across the 4 USB ports. See Raspberry Pi Power Limitations.
This assumes the Pi power supply is adequate.
Whether this would be adequate for 2 SSD drives, depends on the drives.
My experience is that the voltage from the USB ports often falls below that required for power hungry external drives, so a powered hub is ...
6
Yes - the RPi 4 has had some "controversies" (il dibattito?). One is related to a flawed USB-C interface design. The other is not a design flaw, but rather a thermal management issue. Here is a summary, as I understand these controversies.
1. The USB-C Hardware Design Flaw:
The Raspberry Pi hardware design team made a significant design error in ...
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My opinion is that, yes you should. Especially since you are powering an Arduino and a WiFi dongle.
The reason why some often you need a power USB hub is because the RPi itself doesn't have enough juice to power a lot of high amp devices. I have a webcam attached to mine with a Bluetooth dongle and without my hub, the dongle doesn't allow devices to connect ...
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