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So Where’s My Low Voltage DC Wall Socket?

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Re: So Where’s My Low Voltage DC Wall Socket?

#71

Post by kube-system »

paulfurtado wrote: post #53
lostlogin wrote: post #34

More than a low voltage plug (which I’d love) is the need for in wall smart plugs that have a wired connection rather than wifi. I can’t believe I’m the only person that wants this and while I’ve found a few in wall smart plugs, I’ve never found a wired one.

There are classic home automation systems like x10 that potentially predate wifi and offer wired solutions that use the power lines themselves for wired communication, you might want to check these out

I remember playing with x10 consumer devices I bought off the shelf from radio shack 25 years ago. The tech was slow but very functional even back then.

Re: So Where’s My Low Voltage DC Wall Socket?

#72

Post by MisterTea »

mschuster91 wrote: post #57
MisterTea wrote: post #46

We don't need DC sockets as they dont solve any problems. The stupid simple AC mains distribution system is well tested and proven. Who cares that they provide up to 3kW. The "last meter" problem is perfectly solved using AC-DC wall warts and bricks. If the power supply dies, you buy a new one and just plug it in. No electrician required. Putting things in wall or central distribution is not a solution to any existin…

> A better solution would be to get everyone on board with a single DC voltage and connector Why? For many things 6V is enough as it will downscale without too much loss to 5V/3V3 which is what most electronics run on... but everything that draws a boatload of power (computers, laptops, LED strips, ...) will go on 12V up to 24V, so if you want a standard it's either 12 or 24V which will introduce a lot of regulation…

Why? Routers, switches, small embedded computers, and a myriad of devices already use 12-24V DC and step it down internally to 3.3V or less for chip use. Laptops and even phones/tablets are no different. And conversion losses don't increase with voltage so long as you design your DC-DC converter properly.

5-6V is fine for small loads of around 10 watts but you then have to deal with line losses. A 5 m / 16 foot 24 AWG usb cable will lose 38.5% of its power from line losses at 5V, 2.5A (a measly 15 watts). If you wanted to get a low 2-3% loss for 5V, 2.5A at 5m cable length you would need 12 AWG which is massive. 24V does better but if you wanted 50+ watts you again have voltage drop issues.

So in conclusion, low DC voltages are not very practical for power cable runs of over 2 meters. Though it would be nice if the last meter could be more unified with a single DC voltage and connector (my vote is for 24V). Then we can consolidate multiple devices to one strip/brick and call it a day.

Re: So Where’s My Low Voltage DC Wall Socket?

#73

Post by Spooky23 »

Johnny555 wrote: post #12
Spooky23 wrote: post #5

Earlier quoted context omitted.

The author makes the valid point that USB-A is too low power, and USB-C requires active cables. (Translation: expensive or dangerous)

If you want one port that can charge multiple devices of varying needs safely, you need smarter cables. Sounds like a reasonable tradeoff. Otherwise every single cable would have to be built to handle the highest possible power delivery rate (100W for USB-C).

The problem lies in that you're pushing the problem into the hands of anonymous cable makers and clueless end users. It's really difficult to stick a standard plug into a 30 amp socket.

It's really easy to buy some substandard USB-C cable that lies about it's capability.

Re: So Where’s My Low Voltage DC Wall Socket?

#74

Post by MisterTea »

Wowfunhappy wrote: post #61
MisterTea wrote: post #46

We don't need DC sockets as they dont solve any problems. The stupid simple AC mains distribution system is well tested and proven. Who cares that they provide up to 3kW. The "last meter" problem is perfectly solved using AC-DC wall warts and bricks. If the power supply dies, you buy a new one and just plug it in. No electrician required. Putting things in wall or central distribution is not a solution to any existin…

Wouldn't it be more efficient to have e.g. one DC power supply for the house that can power everything that needs DC power, instead of lots of individual (and likely cheap/inefficient) power supplies?

Line losses, see my reply below. Once you go beyond needing 10-15 watts and cable lengths beyond a few meters you start losing a lot of power through the wire.

Re: So Where’s My Low Voltage DC Wall Socket?

#75

Post by testplzdeleteme »

Wowfunhappy wrote: post #61
MisterTea wrote: post #46

We don't need DC sockets as they dont solve any problems. The stupid simple AC mains distribution system is well tested and proven. Who cares that they provide up to 3kW. The "last meter" problem is perfectly solved using AC-DC wall warts and bricks. If the power supply dies, you buy a new one and just plug it in. No electrician required. Putting things in wall or central distribution is not a solution to any existin…

Wouldn't it be more efficient to have e.g. one DC power supply for the house that can power everything that needs DC power, instead of lots of individual (and likely cheap/inefficient) power supplies?

EDIT: Most consumer appliances will still need there own power supplies. You would still want a last step DC transform to house at a high voltage. If the appliance operates at the voltage DC then it would need no power supply.

Yes, and cheaper to build!

You can achieve the same efficiency with DC and AC do not directly effect efficiency across the line contrary to popular belief. It is simple about what the voltage across the line is.

AC was in because it allowed us to build transformers to up and down voltages to provide efficient across the line.

Nowadays, we can build DC transformers with Power MOSFETs which are cheaper, and more efficient then there AC counter parts (old [magnets and inductors] and new [You can do AC transformers with MOSFETS with some extra steps/components]).

Additionally, since most consumer appliances first step is to rectify the voltages most build in the past two decades are DC compatible. Additionally, newer ones could then drop the rectifier stage and become cheaper and more efficient.

Re: So Where’s My Low Voltage DC Wall Socket?

#76

Post by wffurr »

forgotmypwd123 wrote: post #9

I always thought running low-voltage DC through a house from a single supply was doomed due to voltage drop over the distances required....

Boats and RVs do this but the cables are gigantic compared to AC cables. Also as they age voltage drop becomes a big issue, especially on boats since the environment is so corrosive.

Re: So Where’s My Low Voltage DC Wall Socket?

#77

Post by djrogers »

MaupitiBlue wrote: post #6
rhinoceraptor wrote: post #4

It seems like USB A/C are going to be that. You can already buy outlets that have both mains and USB ports, there are even dual USB C outlets now, that can do 30 watts: https://www.amazon.com/dp/B07PTWG5DV

I was going to link to that exact product. I put in the USB A one a few weeks ago and love it. When the iPhone 12 is released I’ll switch to USB C.

Why wait for the iPhone 12? The current iPhone already charges significantly faster over USB-C than USB-A, as do all iPads released in the past ~3 years.

Re: So Where’s My Low Voltage DC Wall Socket?

#78

Post by dboreham »

paulfurtado wrote: post #53
lostlogin wrote: post #34

More than a low voltage plug (which I’d love) is the need for in wall smart plugs that have a wired connection rather than wifi. I can’t believe I’m the only person that wants this and while I’ve found a few in wall smart plugs, I’ve never found a wired one.

There are classic home automation systems like x10 that potentially predate wifi and offer wired solutions that use the power lines themselves for wired communication, you might want to check these out

Powerline Gigabit Ethernet is a thing, but it's bordering on wireless (uses the power wiring as a "guideline" as to where its RF energy should go). This makes the network attachment unit costly and adoption low. For most applications WiFi is cheaper and more convenient. Anyone who wants really solid connectivity will lay Cat5.

Re: So Where’s My Low Voltage DC Wall Socket?

#79

Post by asteli »

MisterTea wrote: post #46

We don't need DC sockets as they dont solve any problems. The stupid simple AC mains distribution system is well tested and proven. Who cares that they provide up to 3kW. The "last meter" problem is perfectly solved using AC-DC wall warts and bricks. If the power supply dies, you buy a new one and just plug it in. No electrician required. Putting things in wall or central distribution is not a solution to any existin…

Wait, that exists. USB is the standard. The UPS with standardized DC-outs is a USB power bank with integrated pass-through charging.

Re: So Where’s My Low Voltage DC Wall Socket?

#80

Post by paulfurtado »

dboreham wrote: post #78
paulfurtado wrote: post #53

Earlier quoted context omitted.

There are classic home automation systems like x10 that potentially predate wifi and offer wired solutions that use the power lines themselves for wired communication, you might want to check these out

Powerline Gigabit Ethernet is a thing, but it's bordering on wireless (uses the power wiring as a "guideline" as to where its RF energy should go). This makes the network attachment unit costly and adoption low. For most applications WiFi is cheaper and more convenient. Anyone who wants really solid connectivity will lay Cat5.

The use case here is turning an outlet or light on/off, so latency matters, but it requires nearly zero bandwidth (assuming that you're not talking tcp). Granted, x10 security cameras exist.

x10 speaks a protocol designed for this purpose and requires a base station.

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