@panic mode i thought in case we use let's say 3-24v dc it doesn't matter where u are and what are standards.

for me... forums like this are all about sharing and cooperation... that means helping each other and 2-way communication. but not everyone feels the same way, some people are only here to ask broad and ambiguous questions while deliberately avoiding any answers to those willing or trying to help. this means those trying to help have to go through unreasonable effort... such as constant guessing and considering every (or too many) possibilities. that stinks of abuse and such people do not deserve my time. bye and good luck...

 

I hope you are not referring to any of my responses.

 

If I was going to wire a house (or RV) with DC power, I'd give serious thought to running 24 to 28 volts (compatible with 24V battery) and using USB-C output modules in the wall outlets. Higher voltage means lower current and less voltage drop, USB-C PD trigger modules can deliver 5V to 20V as required. If the module is QC compatible, I believe it's possible to get 3 volts or even arbitrary voltages of your choice with the right signalling.

hello @bassbindevil ,
thanks - just wondering in case there is a usb-c module which provides lets say 5,9,12V can u attach to it 5v device, i mean who does handshake how many volts has to be used?

it says there is some Voltage detection - but no idea how safe it is and how it works.
https://www.aliexpress.com/item/1005005574705710.html


Okay so it seems i have to attach to the PSU usb PD module and then for each device negotiator "device" for specific Voltage

thanks!

 

that stinks of abuse and such people do not deserve my time. bye and good luck...

@panic mode
Sorry, but yes its about cooperation etc... I dont your point regarding the abuse, what was the abuse?
I just said - not to confuse - that in case we are using 3-24V in that case there is no need to think about "standards"? Apparently you take that as an abuse, which is weird.

I fully agree with your statements that in case device is not approved etc it might pose a risk/issues and also i am still skeptic to buy such devices from aliexpress, but ppl constantly posting references to electronics to aliexpress and i frankly have no clue how these devices are "safe", etc etc. as there are not that many other pages where you can find and buy such devices.

 

Given the large number of advertisements that I see that contain no actual specifications at all, merely describing a product using "glittering generalities", there could easily be products sold that do not come close to meeting the requirements for safe interaction with the devices they are capable of connecting with. So what happens when that universal all voltage power supply zaps your $1100 smart phone with 15 volts because the communications part did not work right??? Was the smart phone supposed to somehow be able to not accept the excess voltage?? And did the universal charger think the phone was a hoverboard? Or an electric bike??
Sometimes the price for convenience is much greater than I am wiling to pay. I use a 5 volt charger for charging the phone. It is a single voltage device, never needs to negotiate.

If I wanted to wire the house for DC, which voltage would I have to select?? And if each appliance needs a different voltage, then still a voltage changing package is required. Why not use a supply that is powered by the mains, and has a standard connection scheme??
Not trying to offend, just pointing out that some problems are a lot more difficult to avoid. Just read those descriptions and notice what is never included.

Back in grade 9 in high school one of our teachers spent a couple of class sessions teaching us how to recognize propaganda, both in politics and in advertisements. That was a very valuable bit of my education.

 

@MisterBill2 these are all good comments and points.

Just not sure if i got the last recommendation regarding " Just read those descriptions and notice what is never included. "

Also agree that in case voltage changing package is required - the thing will be - its quality / reliability (which might be discutable in case buying these modules from aliexpress), but the question would be is there company selling these modules which are really reliable etc.

thanks

 

@MisterBill2 these are all good comments and points.

Just not sure if i got the last recommendation regarding " Just read those descriptions and notice what is never included. "

Also agree that in case voltage changing package is required - the thing will be - its quality / reliability (which might be discutable in case buying these modules from aliexpress), but the question would be is there company selling these modules which are really reliable etc.

thanks

My experience has been that the companies producing good equipment, by which I mean products that perform as claimed and meet the specifications that are claimed, usually provide the details needed to understand what their product will provide. Those suppliers who have something to hide about their products will usually not supply that information, but rather tend to use meaningless generalized phrases about their product.

 

@MisterBill2 got your point ... but for example
https://www.aliexpress.com/item/1005005297596317.html
is it possible to decide if its good or bad product?

for example they are saying that input is 12/24V battery - is it really important if its battery or 12/24V PSU?

 

OK, interesting example. My evaluation is that while it might actually work, it undoubtedly has problems such as excess noise and poor regulation. I would not spend money for it.
IN ADDITION, to me the listing screams that it is junk.

 

@MisterBill2 thanks, seems thats what they sell there..

also how did you find out these: such as excess noise and poor regulation.

well question would be where else to find such a modules/products.

thanks!

 

Why not use a supply that is powered by the mains.....

I recommend you just run mains AC to each point requiring power, which is much more flexible and not going to become obsolete as technology changes. You are already discussing running a higher voltage DC to cater for different requirements, but whatever DC voltage you choose will fail to meet some requirement. The world is designed for AC. I've seen so much obsolete wiring for TV or networks, coax, tp, not to mention off-grid houses wired for 12V, 24V, 48V.

For power, run mains. When you change a piece of kit, it will be compatible with mains, for sure.

 

Switcher power supplies generate noise that must be filtered. That is part of the switch scheme. And those small packages with lots of cooling fins lack the room for much of a filter. AND, with that much cooling, there must be a bit of heat, and heat is the enemy of filter capacitors. THAT is my reasoning.
Aside from that, if they were low noise devices they would claim it as another good feature, which would be true. So it is both what the ads say and what they do not mention that conveys a message.

 

hello @bassbindevil ,
thanks - just wondering in case there is a usb-c module which provides lets say 5,9,12V can u attach to it 5v device, i mean who does handshake how many volts has to be used?

The load device negotiates using the PD protocol which uses a special line on USB-C, or Quick Charge which uses pulses on the regular USB data lines, or some proprietary signalling that some phones have. The USB-C source should default to 5V otherwise, and may not put out any voltage until something is detected on the data lines.

Edited to add: I've tried the CMTPD PD trigger with an Apple and j5create USB-C supply, and it requests the voltages correctly. I haven't tried it with loads yet.

 

@ericgibbs i dont care about warranty that much ... just wanted to "elegantly" get rid of the batteries.

A noble effort- but beware that it's often more difficult than one would imagine.

For example, I was hired to wire up a bunch of battery powered LCD TV units for an art piece- 12 TV's @ 6 volts via 4 AA cells- Easy Peasy!
I measured the current draw- about 70 ma when running.

I got a 6 V, 2 A power unit and tediously wired the TVs in.

When I powered it up- NOTHING!

One TV would work, but not all of them together.

Turns out the TVs have switch mode converters in them which require a large inrush current- the PSU just shut down when all those converters tried to start at once.

I could not fit a monster PSU in there... I had to build a stupid power sequencer to make them start one-by-one.

Lost money on that job.

 

A "shorting" rotary switch would possibly have worked, starting them one at a time. OR a higher current rated six volt supply.
And I wonder how the originally claimed 70mA draw was determined?

 

Switch mode converters could of been just 70 mA but his power supply shut down cause it looks like a short till they start up.
I have a good power supply that 5 amp it will not run anything that using switch mode converter in it
My meter shows a starting load of 150 mA but the short circuit detector made in the 5 amp supply kicks out
i have a home made one that just 3 amps it start up the board all day long and shows it only using 150 mA to start.

 

A "monster Capacitor" may be adequate to cover the startup surge, if the wiring is done right.

 

hello,
one thing is to get rid off different psu of different devices and use "converters",
but maybe I forgot to stress out that another thing is that i wanted to use psu for some battery powered devices... not only just to get rid of the batteries but also to be able to add some other "circuit" and control them using my smart-home.