The DCO - DC power outlets to replace GPOs and wall-warts.
Peter Jakacki
Posts: 10,193
Some time ago I looked at getting rid of a lot of those stupid power-packs (wall warts) from around the house, or at least in the workshop. After thinking about it I decided that I'd run 48V DC in the form of eight 6V 160AH sub-station batteries (freebies less than a year old) through the house and bring it to outlets that provided both this raw power plus a selectable 5A switch-mode output along with several USB charge outlets rated to at least 1A or more each. The cable runs have poly-switch protection for overloads and shorts.
The main reason for the DC in the first place is to provide LED lightning via wireless switching but also power most of the electronics in the house.I like indirect lighting where the lights face up and reflect off the ceiling. I may also do a 48VDC to mains voltage inverter for some appliances too. In the process I decided to try wiring 48V straight to a GPO (mains outlet) and plugged in an LCD monitor which is normally operated from 110..240VAC but reasoning that normally there is a lot of head room in switchers and it may work, which it did, direct from 48V. So besides monitors I can run laptops straight from a simple switcher in the DC outlet rather than those big clunky PSUs they come with and of course every USB charger can be binned as I tap directly into this "grid".
I've also been using those 12V LED reflector lamps for a hand torch, I fitted the lamp to the end of an Eclipse mint can, added a switch, and installed a 9V NiMH battery. It's one helluv light as it's wide beam and very useful in just lighting everything up all at once. I might do an inverter pcb to allow me to use 2 xAAs instead plus some lamps need at least 10V anyway.
Sometime soon though I will have new DCO (DC outlets) pcbs so it becomes a simple matter in running my own wiring as I do not require an electrician for ELV "low voltage" and also just a simple power bus for the lighting with the receiver modules controlling from one to four loads each. A "switch" can control any or all of the lights as need be and there is no reason why a simple phone app can't talk to this through WiFi either.
As for charging that means it now makes sense to install solar panels and instead of that dumb grid-locked inverter which only works when the street grid is live (and sunlight), I can DC-DC convert to charge the batteries directly. A lot of people had those solar panel + inverter combos installed under a government incentive here but when I found out they only work when the grid is live (microgeneration) I decided to do something better instead.
So expect for A/C, refrigeration, and electric hotplates I can run off-the-grid if I need to as I also have solar hot water and there's always the gas bbq. What I probably like the most is that I don't need to pay expensive licensed cable-monkeys and plus I can put my lights where I want as well as the "switches" which are really just tiny transmitters of course. No more drilling through noggins and studs and feeding ridiculously huge cables just for a light switch.
I'm looking into some of Silabs offerings as well as others for creating a Zigbee-like wireless network to make this all easier to control although I do have an option to transmit over the power cable too.Although this would be good as a commercial product I don't think it will take off as there just seems to be too many regulations around, another way of keeping cable monkeys fat.
Has anyone else been playing with DC power to replace mains outlets etc?
The main reason for the DC in the first place is to provide LED lightning via wireless switching but also power most of the electronics in the house.I like indirect lighting where the lights face up and reflect off the ceiling. I may also do a 48VDC to mains voltage inverter for some appliances too. In the process I decided to try wiring 48V straight to a GPO (mains outlet) and plugged in an LCD monitor which is normally operated from 110..240VAC but reasoning that normally there is a lot of head room in switchers and it may work, which it did, direct from 48V. So besides monitors I can run laptops straight from a simple switcher in the DC outlet rather than those big clunky PSUs they come with and of course every USB charger can be binned as I tap directly into this "grid".
I've also been using those 12V LED reflector lamps for a hand torch, I fitted the lamp to the end of an Eclipse mint can, added a switch, and installed a 9V NiMH battery. It's one helluv light as it's wide beam and very useful in just lighting everything up all at once. I might do an inverter pcb to allow me to use 2 xAAs instead plus some lamps need at least 10V anyway.
Sometime soon though I will have new DCO (DC outlets) pcbs so it becomes a simple matter in running my own wiring as I do not require an electrician for ELV "low voltage" and also just a simple power bus for the lighting with the receiver modules controlling from one to four loads each. A "switch" can control any or all of the lights as need be and there is no reason why a simple phone app can't talk to this through WiFi either.
As for charging that means it now makes sense to install solar panels and instead of that dumb grid-locked inverter which only works when the street grid is live (and sunlight), I can DC-DC convert to charge the batteries directly. A lot of people had those solar panel + inverter combos installed under a government incentive here but when I found out they only work when the grid is live (microgeneration) I decided to do something better instead.
So expect for A/C, refrigeration, and electric hotplates I can run off-the-grid if I need to as I also have solar hot water and there's always the gas bbq. What I probably like the most is that I don't need to pay expensive licensed cable-monkeys and plus I can put my lights where I want as well as the "switches" which are really just tiny transmitters of course. No more drilling through noggins and studs and feeding ridiculously huge cables just for a light switch.
I'm looking into some of Silabs offerings as well as others for creating a Zigbee-like wireless network to make this all easier to control although I do have an option to transmit over the power cable too.Although this would be good as a commercial product I don't think it will take off as there just seems to be too many regulations around, another way of keeping cable monkeys fat.
Has anyone else been playing with DC power to replace mains outlets etc?
Comments
design decisions more so people can join in?
Is 48V to allow simple POE or just a good compromise between efficiency of DC-DC conversion
and thickness of wires? Is the voltage critical anyway?
What total power are you envisaging and is the total current/powered monitored?
One issue I can think of is that mains being high voltage has no trouble blowing fuses whenever
there's a short, however with lower voltages there could be a partial short that generates enough
heat to start a fire, yet isn't pulling enough current to permanently blow a fuse... I'm thinking things
like water ingress (I've seen what 240V AC does when water gets in, and its dramatic, but safely
blew a 15A fuse while noone was home - I naively replaced the fuse and then noticed the porch
light fitting spitting water and flame!). Perhaps intelligent fuses are the way to go?
I believe that airplanes use 48 volts, but isn't that 400 Hz AC? Of course, you are providing a backup in terms of batteries. But if there is no real need for backup DC throughout the dwelling, then a localized backup might be easier to manage.
I have these handy little block converts that are sold in Taiwan, but not UL approved. They convert 120VAC directly to 5DV. One could easily be inserted into an electrical box inside the wall, and then you could provide regulated 5VDC from the wall in some plug format.
At some later date, you could remove these and revert to a regular mains outlet. And they do vary in available voltages, some are even dual voltage regulators. The one shown is 4.5Volts and 12 Volts. They don't have a 5 volt/ 12 volt dual for some odd reason.
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I do appreciate the idea that you are not required to hire an electrician for low voltage DC; whereas all AC mains generally requires an electrician (there are places that do allow homeowners to DIY their own domicile).
But I still find it difficult to imagine a situation where you are not going to run into the need fo run some things at AC mains or just go without.
an AC->DC converter is appreciable, whereas a lot of DC->DC converters are truly micro-power under no-load conditions.
Secondly the ability for all your gadgets and network and computing equipment to have an automatic UPS is really useful,
you're protected from brown outs and power interruptions, which for some people is really good news.
But just getting rid of mains power blobs is a major advantage, they are such a nuisance, ugly and a real pain to lug around
when you are on the move (being powered from USB partly addresses this, but not for laptops and more power hungry devices).
The original use of mains electricity was lighting, induction motors and heating, and here in the UK 240VAC was chosen
as a good compromise between expense of copper and the appliances (higher voltages make appliances harder to make
safe, make transformer primaries more expensive, make connectors larger and clunkier etc).
For most of our modern devices we interested in a few watts to a few dozen watts, and DC supply - the
original choice of 240V doesn't make sense for these things, a better compromise between wiring and
appliance costs is probably around 50V, and either DC or high frequency AC (20kHz square wave perhaps).
Arguably the US 110VAC isn't too unreasonable, but would be better as DC or high frequency AC. However
110VDC is a greater shock hazard than AC (DC shocks cause more powerful muscle spasm)
Low amp 5VDC makes sense. The USB socket seems to becoming a standard for all sorts of things.
Re wiring, I guess you still have to follow the AC conventions of running separate loops for power, for lights etc and bring it all back to a switchboard. You could use standard DC breakers eg http://www.electriciansupplies.com.au/shop/index.php?main_page=index&cPath=24_306_468
I'm kind of tempted to do something similar. I have several pure sine 12V to AC inverters that I take with me on the ride-on mower for AC out in the field. Just attach to the 12V battery on the mower, and then at the end of the day I plug the mower into a float charger. So that gives me AC out in the field. It would be cool to be independent of mains blackouts etc - you could plug an inverter into your DC socket in your house and have AC as well.
That 32V plug socket is perfect for 32V. I wish there was a similar one for 12V - the standard for 12V seems to be the car cigarette lighter socket which is not a great mechanical design.
youcan get TONS of telecom dreived gear that way . OR 24 and its easy to get AUTO/AIR laptop buck converters .
My ham shack( bedroom in LA years ago was allmost all 12V based system . from my fridge to the radio to the fans to LED lights .
32V seems less common. Maybe repurpose the 32V plug/socket for 48V?
I guess for economies of scale, it makes sense for a manufacturer to make a device that can handle 100V to 240V, and if it works on 48V too, that is a bonus. One could think of testing devices, if they work, change the plug over to a DC plug.
The switch-mode supply for 1.5A at 5V for instance is only about the size of a 7805T regulator, that's way way more compact than any wall-wart around. The DCO also has a 4-terminal connector for that selectable voltage cable, so that if I had a cable that plugged into one of my laptops then it would have the 4-pin connector on the other end but with a resistor in it that sets the voltage. Without a resistor the output will only ever be 5V and the inclusion of a resistor can make it any voltage up to 48V or even less than 5V.
Also 48V is within the 50V ratings of many components and switch-mode supplies. If I need to invert up to a higher voltage for some equipment it is far more efficient to convert from 48V to 110V vs the big big 12V to 240V that normal inverters are here (great big thick jumper leads just for 600W from 12V). Using simple inductor boost topology and H bridge drivers it should be very easy to generate a 110V sine wave I think.
As I said before I am finalizing the design for my DCOs and the type of 4-pin connector I will be using is at present a 4-pin combicon 3.8mm pitch which is quite compact and rated for 8A operation.