Raspberry Pi 3 B+ Under-voltage Issues

[christophernewman]

I've been working through an under-voltage issue with a more custom setup using the following:

Raspberry Pi 3 B+
MakerFocus Raspberry Pi X820 2.5 Inch SATA HDD/SSD USB3.0 Storage Expansion Board
750GB Toshiba 2.5 SATA drive
HyperX Cloud Headset with USB Adapter
SanDisk 32GB MicroSD Card
Seleven Fm4 2.4G Universal Remote Control USB Wireless Remote Control for Android TV Box IPTV HTPC Mini PC Windows /Mac OS/ Linux
Geekworm Raspberry Pi X820 (X800) SSD&HDD SATA Storage Board Matching Metal Case/Enclosure + Power Control Switch + Cooling Fan Kit
5V 4A 20 Watt Barreled Power Adapter

The issue which would be obvious is I am more than likely running more than the power adapter can handle to a degree at 4A, but wanted to know what my voltage/amperage limitations could be to even this out on my current build. I had considered a 5V 6A with the same barrel size fitting, but wanted to reach out to the community for a better solution/advice on evening out power consumption usage.

Note: The HDMI cable is plugged directly into the HDMI on the TV (No HDMI Splitter involved.)

Thanks,

Chris

[wh7qq]

Your best move would be to strip the RPi back to bare minimum...monitor, mouse and keyboard and if it runs ok, add the next most important item, pausing between each step to power off, attach, and reboot. At some point you will exceed the ability of the RPi to source power. Understand that you may well have a power supply rated for 5v at 4 amps but if the supply cord is too thin or too long or has a switch. the voltage drop may be in the cable. There is a physical/practical limit for the size of conductor to be used with a micro USB plug. You will probably need to use a USB expander with the bigger power supply and it will have a barrel type connector. The big SATA drive may be your villain along with the case and fan it lives in but I have no idea of the contribution of your other gear.

You can total it all up on paper and see how it compares to the supply capacity but the 3B+ will require something over 1.2A just for itself depending on how busy you keep it. The sum of the rest...you know better than anyone here but you don't want to get close to the 4A capacity of your supply. As you increase the load, the ripple rejection and the regulation may start to suffer.

[LTolledo]

Hi there!

Welcome to the Forums!

First I thought you were trying to use 2 X820 HDD/SSD adapters (the MakerFocus and the Geekworm), as further reading the Geekworm is a case to match the MakerFocus + RPi + HDD/SSD setup.

Its seems that the power to the RPi3B+ is delivered to from the X820board.
Also need to confirm if your Suptronics X820 board as v1.3 or v3.0.

If it is v3.0, suspects may be....
1. the 5v 4.0 adaptor's poor voltage regulation. it may be giving only 4.9v when plugged to the board.
2. a large voltage drop at the Schottky Barrier Rectifier (the component labelled MDO SS32, near the 5v connector to RPi).
3. bad connection at 5V connector, causing voltage drop,
4. thought the red-black cable may look thick, it may be have thin wire core inside (less than 0.5mmsq), thin wire causes voltage drops.

I second what wh7qq recommended, that is running the RPi3B+ with the bare minimum (microSD version) to see if RPi3B+ works first. Use 5v 2.5A PSU (not phone chargers)
then try SSD only version (not use the X820 board), via a SATA to USB3.0 adaptor, use 5v 2.5A PSU
then try X820 + SSD + 5v 4.0A PSU
then pack it all up beautifully in the case.

[christophernewman]

Thanks everyone.

I did do some voltage checks and 1-by-1 peripheral comparisons. Only saw a voltage issue when data is pushed/pulled via ethernet (i.e. transferring files to and from the pi).

Verified a slight uptick in amperage (i.e going 5V 6A or 5.1V 6A) would mitigate this with the current custom build I have.

Thanks again everyone,

Chris

[HawaiianPi]

I very much doubt you are pulling more than 4A with that setup. It's far more likely that your PSU has poor voltage regulation, or that you have some excessive resistance in power delivery wires/connectors causing voltage loss.

Regardless, going to a 6A power supply will not help if the devices you have are connected to the Pi USB ports. The internal poly-fuse will not allow more than 2.6A of current through the system, no matter what your PSU is rated for (max power from the Pi3 USB ports is 1.2A, period).

You could try re-wiring your setup to power the HDD directly from the PSU to reduce the load on the Pi USB ports (assuming you know how to do that properly).

[christophernewman]

That's what I thought to until I tested 4 different adapters.. different brands.. batches.. same voltage and same amperage, etc. As for rewiring i could, but It's all pretty much a singular board with 2 outlets to power switch side of board and 1 for power to fan so it would defeat the purpose of my intentions of the build (i.e. as much as possible without solder ). I may consider adding a voltage regulator between switch board side to pi.

Either way I should have it figured out soon.

[Brandon92]

Hello,

I found somewhere on this form that the 3b+ has two setting for the power delivery. Here is the closest post I could find for know. The command should be some were on the forum. But maybe this is not from this time any more, I don't know

Same poster, same question:

According to USB-2.0 specification an USB device may draw up to 500 mA (USB-3.0 a bit more). If an 2.5 HD enclosure with USB 2.0 and no external power supply is sold, it should not use more.

The old B (this is a bit mixed up in this thread) was never made to supply 500 mA on its USB ports, The B+ delivers either 0.6 A or 1.2 A, dependent on a configuration setting, on all four USB ports together. This requires a good power supply with stable 5V at 2A (and a good power cable!).

With the high power setting enabled, the B+ should be able to feed two low power (100 mA) and two high power (500 mA) USB devices.

Connecting one USB 2.5 drive should always be possible, if all conditions are met. But don't use any of these crap "USB loaders"; use a good 2A switched power supply and a good cable. And use an USB-2.0 drive, not USB-3.0. If a drive is sold with an Y-cable, you can be sure, that it doesn't meet the standards, so don't use it.

[rpdom]

Hello,

I found somewhere on this form that the 3b+ has two setting for the power delivery. Here is the closest post I could find for know. The command should be some were on the forum. But maybe this is not from this time any more, I don't know

That post was about the (1)B+, not the 3B+ (Note the date of posting. The 3B+ didn't exist in 2014). The 3B+ only has one setting - the full 1.2A.

(Actually, the (1)B+ has the high power setting turned on permanently now. There wasn't much point to the lower setting).

[Brandon92]

Okay. The post was indeed a long time ago. Bit I thought that I had read it also for the news one, in another topic. Prahaps I read it wrong then.

[HawaiianPi]

... Actually, the (1)B+ has the high power setting turned on permanently now. There wasn't much point to the lower setting.

As I understand it, the hardware still defaults to 600mA until the kernel loads and tells it to switch. So it's Raspbian that now has the high power setting on by default. That may not matter to some (and certainly not to the OP who has a 3B), but for those trying to boot from a USB HDD on an older model, it can be a problem (if the drive can't spin up, the kernel will never load).

As for the OP, I don't know how to help him as he just rejects all help offered. ¯\_(ツ)_/¯

[rpdom]

... Actually, the (1)B+ has the high power setting turned on permanently now. There wasn't much point to the lower setting.

As I understand it, the hardware still defaults to 600mA until the kernel loads and tells it to switch.

It's more likely that it's a "firmware" change, but your point is still valid.