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After switching to solar DC and batteries I suddenly cared a lot more about ac/dc power inverters needlessly wasting my limited energy supply.
Slowly I figured out how to power my devices without ac outlets. Mercifully 5v,9v,12v,19v at 1-5A are pretty standard values for most lower powered DC appliances.
A good DC barrel plug 5.5mm universal adapter kit, a usbc-PD adapter cable with manually selectable voltage levels to 5.5mm barrel plug, and a car plug to dc barrel plug universal adapter kit have taken good care of 95% of my adapter woes.
It feels sooo good to figure out how to power something directly with USBC and see the wattage drawn get cut down significantly.
Whats my point? If people knew a little bit more about the finer details of power supplies and dc barrel plugs most of their box of junk cables could be phased out with confidence. If you have 20 year old electronics with some weird incredibly specific voltage and barrel plug I would heavily consider just getting a new version that runs on usbc-pd or a more standard power rating. And if I ever need an old video cable? You'd better believe amazon and eBay still got it.
I really like your comment. Nothing gets me going more than eliminating unnecessary waste and streamlining the system to a simpler one, even if it is more work. 😤
You have inspired me.
Are you suggesting that modern USBC power supplies don't have that parasitic draw that other DC power packs have?
They have solar + batteries, so they have to convert the sun into DC, hopefully directly supply that DC to their batteries, then convert that DC to AC power, then convert that AC power back to DC. Converting AC to DC or vise versa is a reasonably lossy process, so not doing double the conversion is even better.
Also some less than ideal setups convert solar directly to AC, so in order to charge your batteries you have to convert it back to DC.
Thanks, glad to have inspired you! The other person who replied is spot on. I have an entirely DC system so my main advantage comes from cutting out pointless double-conversion from dc to ac back to dc again. Powering on an DC to AC inverter is a parasitic draw that consumes enough power to eat through a good amount of battery capacity if left on by itself. Then using that AC inverter just to power another inverter to step back to DC introduces even more losses and parasitic load. So, its worth my time to try figuring out ways to directly power devices by directly converting DC to DC voltages and cut those needless loads out greatly boosting total efficiency.
USBC-PD technology is an incredibly useful innovation for direct variable dc to dc voltage supply. Specifically a 100 watt usbc-pd charger can supply 5v,9v, 15v, 20v at up to 5 amps (5Ax20V=100 watts). A car cigarette plug can supply 12V at 10A or 120 watts of power. Together they can directly power a great many household DC appliances off of batteries powering a DC to DC inverter.
For some examples:
A 24" lcd computer monitor at full brightness consumed 50Wh through AC inverter. It was brought down to 25Wh running through DC inverter. On half brightness it consumed 15Wh and 10Wh at minimum brightness.
A thinkpad laptop full brightness was 25wh idle -50wh full load, then brought down to 12-20wh.
My nintendo switch game console docked into the lcd screen consumed about 15-20Wh with inverter, brought down to 10Wh.
Desktop dry herb vaporizer (Arizer Extreme Q): 80Wh heating up, 30-50wh idle brought down to 50Wh heating up 15-25Wh idle.
Electric blankets. During the cold months using my electical energy to help keep warm is very important to me. But I cannot keep a regular house electric blanket on for more than an hour or two. I could not keep a car plug blanket on overnight at 80wh. I could keep on a USB powered blanket on overnight at 10-15Wh. And you know what suprised me most? It was damn warm, when I figured out the right way to sleep with it. Have to sleep on it as a matress warmer and layer some heavy blankets on top and let it warm up for an hour or two. But it works and works well. The USB blanket doubles as wearable poncho too which is nice. I wish a USBC-PD one existed with variable wattages.
So as you can see each time I macguyver a way to directly power these devices the total power usage is cut by almost half per device. To someone else who can afford an array of solar panels and a massive bank of batteries they can get away with not caring about saving 20Wh here or 15Wh there. I have a very modest system of 200watts solar feeding into ~400Wh battery capacity total so these savings mean the difference between my batteries being dead overnight and having lots of spare juice left over to brew a cup of coffee with those AC inverters when I wake up.
Of all these devices listed, the LCD monitor is one that has a noticable parasitic load even when the screen is off it consumes a noticable amount of power at idle. The way I would deal with most instances of parasitic draw like this is to find a product throws a physical switch to manually cut contacts with the DC-DC inverter when not being used. In this case a car plug extention cable with a knife switch built in would work great.
Okay so the magic sauce here is USBC-PD which is some type DC-DC voltage converter. Then it's just a matter of barrel connector roulette to find the appropriate plug for each device.
I live part time out of an RV semi-off grid for some of the year and the "using AC/DC power packs off an inverter" always struck me as super dumb which your data basically confirms.
What you've given me is a roadmap to figure this out without having to reinvent the wheel.
You got it man, right on. I would like to give you some more information about the usbc-pd stuff and some of the things I figured out with it. So here is a link to the farsense usbc-pd to standard DC 5.5x2.5 adapter with manually selectable voltage based on button press. This cable is the most important part and I will explain why its so important. USBC-PD essentially requires three things to work right.
The first thing is a charger(the DC to DC inverter in our context) ideally rated at either 65w or 100w as both of those support up to 20v the difference being 65W can only go up to like 3.25 amps or something like that. The simplest and cheapest dc to dc chargers are usbc-pd car plug chargers which convert the 12v from a car battery to the required voltages. The anker one I just linked is a little pricy you can find them for cheaper but it seems good quality and I like the cable I bought from them.
Speaking of, the second thing you need is a USBC-PD power cable that specifically supports the same wattage your charger outputs. Not all of them are rated the same you gotta use a specifically rated cable that handles higher voltages. If you use a 100W charger gotta get a 100W cable. I've had good luck with this anker one
The third and most crucial thing to understand for our purposes, is that you need a communication chip on the appliance side that tells the charger/inverter what voltage to send. The nice thing about that farsense manual voltage selector cable is that it has that communication chip built in with all the different voltages to pick from. Thats the real secret sauce of this setup. That cable and its ability to choose voltage levels is the heart of it. All thats left is to track down the specific dc 5.5x2.5 to X adapter bit and select the proper voltage on the cable and its good to go.
There are USBC-PD adapter bits that have this chip built in for a specific voltage, commonly for laptops at 19-20v. If you manage to track down the proper usbc-pd to barrel plug adapter at your specific needed voltage it will cut out having to manually set the voltage each time you plug it in compared to the farsense cable. But it may be hard tracking down such a specific adapter bit.
Yeah I have a handful of USB-to-random 5v nonsense adapters and they've saved my ass so many times.
Oh I never of this. So do you have different electrical systems in your house for each voltage or how does it work?
I am off-grid for much of the time so I rely on an entirely DC to DC system. 200 watts of solar panels power up my batteries which supply 12V at a capacity of about 400 watt hours. So for many appliances like laptops and speakers and computer screens which use DC power it makes sense to try to convert the voltages directly though other means than the typical AC to DC power plug supplies that you usually use in homes. Doing this I can cut down total power consumption for each device down by about half which is really important for conserving power on a limited energy supply.
In a theoretical scenario you could totally run a seperate voltage line for DC energy through a house, though this has several complications. The main drawback of DC energy is that the lower the voltage the more resistance losses you get running power through a foot of cable. So the cable losses would become signifigant after running 200 feet of cable probably less even. You could bump up the voltage to 48VDC for longer stretches of wire and to power high end RV appliances but now were loosing some of the safety that comes from a lower voltage DC system. Im not familiar with commercial solar installations in homes but I think its easier and more economical to eat inverter losses and use the batteries to supply AC power using preexisting wiring. If you were building a offgrid home its a design thing to consider, reducing and centralizing wiring and appliances.
But then what are you doing? Are you connecting your laptop directly to the battery with shorter cables?
Thank you for taking the time to reply, this is very interesting.
I have my portable folding 200w solar panels on the ground and run about 20ft of weatherproof cabling running along the ground through a small inlet hole into my residence. They connect to my battery system which is located in a good central spot for all my electrical stuff to comfortably reach. Everything I own that runs on electrical power that cant be powered with portable rechargable battery banks is located in the same room as my batteries.
I can deliver DC power through car plug ports, USBC-PD 100W and regular usb A outlets. The 600w AC inverter is useful for brewing cups of coffee, running fans, and turning on a desktop pc for advanced GPU workload stuff. Its important to keep that ac inverter off most of the time especially at night so prefer using car plug adapters and USBC-PD to directly power most of my DC appliances with variable voltages instead. From the car plugs and usbc-pd charger ports, I run my dc appliance cords to my devices which are usually 6-10 ft long. My laptop is usually powered up through a car port travel adapter but I can also use USBC-PD and an adapter bit if the car ports are all taken up.
Thank you for showing interest if you want to know anything else ill be happy to explain. lowtechmagazine's "Slow Electricity: The Return of DC Power" is a great read on the subject the info has been very useful for my purposes. They cover residential dc wiring like we are talking about and its located around the end of the article in the 'How To Limit Cable Losses' section.