I got a new Pi 4B starter kit from Core and one of the extras included in the kit is a USB-C inline power switch. When it’s inline, the Pi reports low voltage. I am using an official 5.1V 3A USB-C adapter that comes with the kit. When the power switch is removed, then I don’t get low voltage warning. I attach a Dell wired mouse and a an older Apple iMac wired keyboard to the USB-2 ports. The HDMI is also connected.
I don’t have any other peripherals to test with but I would have expected no dramas with this setup and the inline power switch. Is this device supposed to work reliably? I noticed the cable says it’s 20AWG versus the Raspberry Pi power adapter’s 18AWG - technically 20AWG should handle it but perhaps they should have made it with 18AWG cable to prevent low voltage?
I am no sparky - but I am disappointed in this little gadget. Of course I can live without it, but I am wondering if it’s a dud concept.
cheers
Arne
PS: The 32bit OS has had one software update since I got it on Christmas.
AWG is the thickness of the wires in the cable, which shouldn’t make a noticeable difference in this case.
The page for USB-C In-Line Power Switch Cable for Raspberry Pi 4 (CE06575) - supplied with the RasPi 4 Starter kits - specifically says “The inline switch will not work with USB-C “Smart eChargers” or the Raspberry Pi 5 Adapter because only power pins are passed through (data pins are not)” and “Not recommended for applications using over 3A of power”.
I think the issue is that the inline power switch is not following the full USB-C spec with all 24 pins connected, and without the configuration channel the RasPi and power supply are not able to negotiate how much power to provide … resulting in the RasPi getting the default 5V 3A - which is just enough. Not much of a difference, but the low voltage warning is annoying … however it is just a warning.
I think the inline switch concept is reasonable. RasPi doesn’t power down when turned off; and it has to be powered off and on to reboot - which can be a pain to do at the Power switch (especially if power supply is in a multi-way power board without individual switches). It is the execution, often based on the older style USB cables with simple power wires, which lets it down.
You might be better off with USB-C Extension Cable with Power Switch - 1m (CAB-25579), which states “Not only does it switch VBUS power, the USB 2.0 D+ / D- pins, the two Configuration Channel (CC1 & CC2) pins and the shield are connected too.” More info, but not really clear whether it would support the full USB-PD.
I note that most USB-C cables don’t give much information about which version of USB 3 standard they support - I guess we should assume basic functionality unless specified
P.S.
When the RasPi 4 was released there wasn’t a lot of 64-bit ARM software about, and 1MB or 2MB wasn’t really enough RAM to take full advantage of the 64-bit address space … so sticking with the 32-bit OS was sensible then.
You didn’t mention how much RAM your RasPi 4 has, but I would suggest that most recent program development has focussed on 64-bit … and so now 64-bit OS might be a better long-term option. Of course if you’re just starting out and learning, then it really won’t matter yet.
Note also that it is so easy to load another OS onto a different microSD card and swap them. I have several so I can have one project per microSD card.
Yeah I also read those comments. I disregarded the Pi5 statement because I have a Pi4. And the charger they put in the kit is designed for the Pi4. Is it a Smart eCharger? I have no idea. I wonder why a starter kit would include an item that doesn’t play well with the rest of the gear. Rather leave it out in my opinion to avoid this kind of disappointment.
I read that Low Voltage warnings can (or will?) throttle the CPU. I have not run any benchmarks yet but I was going to do so to see if it was true.
I don’t know if the good folks at Core Electronics read these posts, but I’d love to hear their reasoning for including this switch in the kit.
About the 32bit addendum. I have the 4GB version and I think I will install the 64bit although the advantages might be academic at this point, because 4GB is the most a 32bit OS can address. My Pi2B only had 1 GB - I have to admit I was expecting the Pi4 to have more snappy GUI response, especially considering everything I have read about it. It’s early days and I got it as an upgrade to my Pi2. I used that little device in my networking lab works (testing client software) - very handy because I could power it from the 5V of a Cisco switch’s USB port.
Hey there, @Arne310045, and welcome to the forum. Glad to have you here.
I can confirm that it’s a common issue with the inline power switch. In my time using it, I’ve never noticed an actual drop in performance, but those Low Voltage warnings are so annoying that it’s honestly worse. I had some success disabling it in the past following these instructions:
But I must admit that ultimately I just stopped using the inline switch.
Thanks @Jane - I’ll give that tweak a go. And you’re right about the CPU performance - my go to (poor man’s benchmark) is to run an ‘openssl speed’ and then compare the results - they were identical with and without inline power switch.
Moving from the official 18AWG down to 20AWG (plus the extra length and the switch itself) adds just enough resistance to cause that drop. Most of those generic switches aren’t really designed for the 3A+ peaks the Pi 4 hits. It’s annoying, but the official PSU is really tuned to deliver that extra 0.1V specifically to account for cable loss - something these inline switches just can’t keep up with.
- I have to admit I was expecting the Pi4 to have more snappy GUI response, especially considering everything I have read about it. It’s early days and I got it as an upgrade to my Pi2. I used that little device in my networking lab works (testing client software) - very handy because I could power it from the 5V of a Cisco switch’s USB port.
