Under voltage ghost is haunting me

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Hi, I’m receiving under voltage notification on my Pi3 running home assistant. I purchased this PSU because there was a YouTube review of it and the guy ran HD’s and HDMI and no under voltage was detected. The PSU is a 5V 3A 15w PSU so should be enough to run the Pi plus hard drives etc.
Obviously there is a problem somewhere. Could it be the Pi or has the PSU really failed.

The only connections to the Pi are Ethernet and SSD. So I wondered is it possible to disable the Wi-Fi. Would that help? I have disabled blue tooth.

I am running 20 sonoff switches and a home cinema from it. Everything is just on/of commands and source select. That seems quite small compared to what I’ve seen some of the guys running. My Processor never gets above 30 percent and the memory not above 0.7GB

I am starting to wonder if running HA on a Pi3 was a good idea.

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If you are getting power warnings then the psu is not up to the job. Whatever you do is not going to change that. So try running the SSD from a powered usb hub.

Might be worth putting the HA on an SD card for a test to see if it is the SSD drawing too much power.

A 3a psu should be plenty of power but unless you can test the power output you can’t be sure its producing what is written on the label.

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Thanks for the reply Arh.

This is the third PSU. All have been ok at the start then the notifications begin. That’s why its so frustrating. The first was a multi block USB charge but only 2.4 A each USB. So this new one was supposed to be the final fix.

What are your thoughts on the Wi-Fi? Do you think disabling it would be reduce the load also?

I have the HA OS on a SD card and the data on the SSD. I have found this to be the most stable so far.
To be honest if I need to have multiple PSU’s then it start to defeat the point of using a Pi. Which is a shame as I Love my little Pi’s. Maybe it’s better to migrate to a different platform like a NUC or DEL mini.

My end goal here is complete stability. I know, try not to laugh.

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The Pi itself have a limitation on what it is able to draw from the PSU, so if your SSD draws more than the Pi can draw from the PSU, then you will have an undervoltage you can’t fix with another PSU.
Some SSDs are actually quite power hungry.
A powered USB hun might help here.

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An SD on a Pi with an Additional SSD is the most Unstable way to run IMHO. Because the two most common failures in a Pi are…

Under volt because the devices on a pi draw more than the ps can provide - as wally said this is a limit on what a pi can draw on USB (and until they start using USB C PD this won’t change no matter how good your power Puck is ~5v3a is the max) to combat this put as much of your load on a powered usb hub as possible.

(be aware of the interference possibilities SSDs do to various coordinatior sticks you may need two hubs - one for sticks and one for the SSD)

SD failure because the SD simply isn’t made to handle constant DB writes. It Will wear out (because physics) yes you can get extend wear cards and try to limit the recorder DB writes but at the end of the day you’ll replace the card eventually. Maybe the MTBF of the card used like that (about a year on average depending on your specific card ) is okay with you. For me it’s not. To combat this - SSD. But move the whole thing. Os and all. But then see the first common failure. :wink:

Almost certainly you’re over drawing it. Mine pi4b8g is almost onto the edge all the time too

Yes a Nuc or similar does not have this kind of issue because it has a builtin PSU that is not limited to the power capacity of non-Pd usb.

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Thanks for the responses.

I think on the whole it would be better to run my HA on a different system. It’s enough just trying to learn HA without the problems the Pi seems to add to it.

I will start looking at ARM based mini’s first as they seem to have the lowest power consumption. Unless anybody has any better ideas?
I’m after maximum stability with minimum power consumption. I don’t need a 12 core cpu that for sure.

The idea is that this system will have to live and stay with the house. So I need it to be as bullet proof as possible.

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Question - this part?

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I’ve installed sonoff tx1 and tx2 Wi-Fi wall switches to the whole house. They can be switched manually or by HA via Wi-Fi. I also have a home cinema also controlled by HA. So whatever system I build to run HA must stay with the house when I move out.
The user interface is by tablet with a stripped down dashboard. Which will also stay with the house if I sell it.

I’ve just had a look at old laptops which may be a good idea as they have a built in UPS.

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I had undervoltage notifications on one Pi a long time. What fixed it were some heatsinks.

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Hi.
Yes I purchased some mini heat sinks when I got the Pi. I think they they help.

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Thats what I thought. Had to check.

No. The controls need to stay with the house (the sonoffs) but do not plan on handing over a configured system.

Think of it this way. There is zero way to properly secure a HA install to hand over to someone. (take a moment and think about how many times you put credentials into HA of some service somewhere…) Amazon, Google, withings (health data, your Amazon account and the ability to purchase stuff)

You say don’t worry I will pull my credentials before I had it over.

A new owner should not accept said device, because they have no assurances you didn’t leave a nice present in the form of malware (yes I know you wouldn’t but) and would never be able to enter credentials into that machine safely. Else worry about thier credentials or data of same being stolen.

The only way to make 100% sure. Wipe and load.

Besides realtors will tell you they don’t want to sell your smart home (really yes smart scares off as many buyers as it attracts, and really as much as we all love the little things we do to make our Smarthome smart, someone else has thier own ideas on how it should work.) so the general current guidance is shut off the smart before you sell.

If you then say but hey it doesn’t work properly without HA running. Then it’s a bad design.

Instead plan on if you ever move. When you go to show the sale, turn off HA and cover your wall mount tablets and sell as ‘smart home ready’. Inform the buyer that hey everything here is built to be controlled. Here’s the specs and manuals of everything and if you buy it we’ll have a of that over, factory reset and ready for you. Btw heres a neat new ha green (or whatever is the current new thing) in a box and a nice bottle of champagne to enjoy while you learn about the new smart home you’re going to get to setup or have someone set up for you.

That way., you don’t get into a contract pickle where the home doesn’t do what you said it does on the showing. And you get a clean break from being thd new owners support for HA forever.

Yes it sounds very uncaring and not really friendly but there’s no way you can provide proper security and hand over a configured install. That way it’s about being aware of that and making the transooas easy as possible. (this goes for any smart home system)

Maybe one day someone will invent a way to cleanly break out a your credentials and find a way to keep the function while assuming a new owner a logic bomb isn’t in the system. But until then this is the only way. Sorry.

You wouldn’t hand over a configured laptop to someone. One company buying out another wouldn’t keep the computers without wipe and load.

Same thing with the house. Fortunately it sounds like you have a pong time before you need to worry about it so just make it part of your sale plan now and you don’t get backed into a corner later because you showed function that the house only can do with a preconfigured system and you have to sell it that way to keep contract and suddenly become the new owners support forever. (way too many people get caught in this trap already)

And yes I have well over 100 controllable points iny home and even more sensors… I will hand over the zigbee and ZWave sticks with thier keys (I can prove those are safe and that way they don’t have to rejoin a couple hundred devices), wiped wall tablets, a brand new box to run HA on (price that into your asking) and a manual. That’s all they get.

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Thanks Nathan.

Lot of sense there and very helpful.

I really don’t want to set myself up for a 5 year 24 hour tech support hotline. That’s for sure.
On handover the only thing that will be different from a normal house will be the light switches and they can be operated as a normal touch switch.

But first I have to get the thing working properly.

What platform is your HA on? I’ve found an old laptop and am thinking of migrating to it. Then it can sit in my network cupboard with hopefully less problems then the Pi is having.

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I have run HA on a small fanless laptop without any issues. Just make sure that it has UEFI.
The benefit with a laptop is that the battery actually works like an UPS and only require a few command line sensors to read the battery status, the charging status and the charger connection status.

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Mine has been on a Pi4b8g for about three years. It’s been stable after all the normal things we fight with on Pi. I’m playing around with voice and trying it into my phone system when thay gets serious the Pi cnt also handle that so I’m probably looking toward a Nuc or equivalent for the next thing. I do IT all day long and don’t feel like managing a server farm for the house all night so I probably won’t ever be a Proxmox /docker /whatever person.

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Hmm. What is the hardware bottleneck here ? If you supply the Pi directly with 5V over the GPIO header, circumventing the USB power-in completely, wouldn’t this solve the problem ? The power supply of the additional USB ports should come directly from the main 5V rail. So, circumventing any type of regulator by injecting directly into the vdd rail, the only limitation I could imagine would be trace width. But in modern PCB designs that would be weird, as multi layer PCBs will commonly feature both a ground and a power plane with complete copper fill. That should be able to carry plenty of amps.

Since the Pi is not open source hardware, it’s very difficult to find a full schematic. The power regulation circuitry seems to change a lot between Pi revisions (even within the same family).

Been using a Pi3 for years without issues. With the official Pi power supply. With several RF dongles connected. Then again, I don’t have an SSD, so that may be the reason.

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Never tried that setup, so can’t say if it will work.
I have tried adapting an USB adapter to a lab power supply that could easily deliver 20A,but that gave nothing, so there must be some electric circuit that prevents it from drawing more through the USB.

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Yeah, looks like some (but not all) revisions of the Pi3 and 4 will route the USB power through a combination of a mosfet and a BCM857BS (probably to avoid backpowering the USB), while others have a direct connection to the 5V rail with just a zener and a thermal fuse. The former anti-backpower circuit could be the reason for the limit.

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I’m not running anything vital on it. But I did want to have a look at voice control next so as you say maybe it would be a bit too heavy for the Pi3. I have a very basic laptop here. So after the new year ill migrate my HA to it and throw it in my IT cupboard down stairs. Oh and then run some microphone cables to the laptop. Honestly I didn’t want a second job but I think I got one.

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Thanks for the reply. I think the Pi3 is great for some applications but I just need it to work without issues and the log files seem to just grow and grow. I really like the low power consumption of the Pi’s.

I think long term moving to an old laptop in a cupboard would be a better idea. Maybe see if it can run in Win 10. That way it has a built in UPS also.