Skip Navigation
170 comments

  • Usbc-pd is an absolute game changer as an off grid person. The fact a 100w charger can act as a dc to dc converter with up to five output voltages, at up to 100 watts is crazy. And that the protocol automatically detects and communicates the proper voltage is very convinent. The problem is that usbc-pd 100w chargers are expensive and you need to know what you are doing if you want to diy power appliances with it.

    Its really nice to have a standardized cable that just works and can be plugged in both ways. We really are approaching a Universaal Cable after a quarter century of RnD.

    • I'm curious as to what exactly you do with it as an off-grid person, and what you mean by DC-to-DC converter.

      • Im happy to explain pastermil. So first off let's talk power.

        Electrical Power Systems

        Most off-grid electrical systems have a few major components.

        • A device that generates electrical energy
        • A battery that stores excess electrical energy for later
        • A charge controller which regulates the incoming raw electrical power from the generator as it charges up the battery, and smooths out the battery energy output
        • A power distribution interface which allows for connecting appliances to the batteries in a safe standardized way.

        My particular electric system has a 200w 28v solar panel for power generation, two 20ah lifepo4 batteries connected to double capacitance, and the charge controller doubles as a very basic interface with two usba slots and a car cigarette port.

        AC vs DC

        Now let's talk about AC and DC. Theres essentially two kinds of electrical power people deal with.

        The difference between Alternating Current and Direct Current is in the way the power flows. Direct current moves in a straight path. Alternating current moves power back and forth in three perfectly spaced cycles.

        AC The one most people are more familiar with is AC power. it comes to your home from power plants through power lines and transformer boxes. You move around extension cords and plug the three prong outlets into a wall.

        Alternating Current (three phase) power is very easy to transmit long distance however its very high voltage. So only certain power hungry devices like kitchen appliances, washing machines, dryers and AC compressors use it directly. Most of your consumer home devices need to convert AV power down into more manageable DC power.

        DC Offgrid electrical systems with batteries are Direct Current by nature. All your power comes from the battery banks. The power moves straight from battery terminal negative to positive. It flows right through your appliances in one way out the other.

        The battery banks tend to be arranged into 12v, 24v, or 48v depending on the systems power draw and transmission needs.

        The popular standards for delivering direct current are:

        • 5v 2.4a usb (15 watts)
        • 12v 10a car cigarette plugs (120 watts, can be rated to supply 24v fused 15a I believe though not common at all)
        • circular dc barrel plug connectors, the most common size is 5.5mmx2.5mm but there are dozens if not hundreds of slightly different barrel plugs. Part of what makes usb so great is reducing arbitrary manufacturing complexity like this.
        • usbc-pd various voltages depending on charger, cable, and device at up to 100w for current protocol.
        • solar quick connects tend to be for connecting and transmitting high voltage DC power to charge controllers and power banks. Its worth mentioning but not that relevant to what were talking about.

        Most consumer devices in your home dont actually use wall outlet AC power directly, it uses wall power thats been converted and stepped down to DC power.

        Desktop computer power supplies, Laptops, monitors, vaporizers, led lights, DVD players, audio speakers, your phone. everything that can powered by usb and batteries. Everything that has barrel plug inputs and power bricks plugging into it.

        If you look closely on the power bricks plugged into the appliance you'll see that it has an input and output voltage rating. The input tends to be 120vac here in america 240v over the pond, and the output tends to be either 5v, 9v, 12v, 15v or 20v DC usually up to 5 amps.

        Device vs Voltage Examples

        Laptops and computer monitors tend to be 20v, fast charging smart phones and the Nintendo switch docked are 15v, very bright home LED lights can be bought that are powered at 12v directly, the ps2 could be powered with 9v, and most usb devices charge at standard 5v. Would you like to guess which voltage profiles the USBC-PD protocol is capable of? Its all of them.

        Energy Conversion Efficency Losses

        Now let's discuss energy efficiency. Converting from AC to DC eats up some of your power. So does converting from DC to AC. And its not small losses either, each time you convert its about a 15% total loss in efficency.

        This loss through conversion doesn't matter when you pay cents on a kilowatt and have unlimited power at the tap. It adds up very quickly when you have a limited power supply and every watt hour counts.

        Let's say I want to power a laptop on my offgrid DC system and my only means of powering it is the AC power brick cable that it came with. I would need to:

        1. Convert the DC power of the batteries to AC through an inverter. 15% efficency loss.
        2. Then convert that power right back down into slightly different DC with the power brick plugged in. 15%% efficency loss.
        3. The inverter and power brick are both parasitic draws. They eat a bit of power just sitting there even if nothing is being powered. Lets add 5% total system efficency loss each.

        Add these up and you get 30-40% of your power eaten away by this needless double converting. Wouldnt it be really nice if we could convert the battery DC voltage directly to the appliance DC voltage without those power hungry inverters and transformers?

        What DC-to-DC Converters Are

        Thats where dc to dc converters come in. They can convert one DC voltage to another. They still introduce efficency loss but way way less only 10% total.

        Traditionally you would hope your device had a commercially available 3rd party travel adapter for 12v car batteries. The dc to dc converter is built in and uses car plug.

        If you were SOL you has to wire up boost converters to raise up voltage and add resistors in series to lower it. You ever try to wire and solder your own circuts before? Its a tedious experience. Imagine doing that for each device voltage. Oh wait, you dont have to. Here's what that looks like.

        A USBC-pd 100w charger that plugs into a cigarette port or is built into a power bank can convert a batteries 12vDC into 5v, 9v, 12v 15v, and 20v dynamically depending on the device.

        Do you know how magical that is? How much trouble that saves when it comes to mcguyvering a DC appliance that only came with AC cable to supply proper power directly? All I need is a 10$ usbc-pd to barrel plug cable that manually selects the voltage needed and some barrel plug adapter bits to fit into the appliance. Energy efficent and simple wiring. All the dynamic controller stuff is abstracted away in a safe way. Powerful enough to deliver 100 watts of power, and its going to be more powerful over time.

  • Last week I found out that there are off-brand batteries for my DSLR cameras that can be charged directly through USB-C so I don't have to pack a different charger for every camera. Let that sink in!

    Overall pretty great, in a pinch I can charge my laptop on a Nintendo Switch power supply. Now if I could just upgrade the last few remaining Micro-USB and Lightning devices without spending a fortune...

  • Like others, USB-PD is amazing. My monitor has 90W which is plenty for my laptops. Gaming laptop, not so much. The only device I have that isn't USBC/Thunderbolt is the damn mouse. I rarely ever need a USB A port for anything other than charging. Even my flash drives are all USBC.

    I have been able to use 1 charger for almost everything for several years now. Sometimes I have a finicky device that doesn't like the high wattage PD chargers and will only trickle charge, but work fine with my other smaller charger. The GaN chargers are nice and compact. I break USBC cables a lot less often, but that is because I am a walking disaster most of the time. I would break micro USB cables constantly, or rip the ports to pieces.

    One note though on USBC ports on a monitor. Beware using the really really stiff cables on ports that are positioned where the cable would be parallel to the table instead of the port pointing down. That port will definitely wear out or break entirely from the constant downward force and lack of support of the cable in the port. This is especially true if you use a monitor arm and the cable gets moved. Seen this on both Samsung and LG. My Dell points downward. I really like the pro PS5 controllers as it comes with a little cage that holds the USBC cable in place and protects the port from exactly that scenario. These monitors absolutely need something like that, especially with how expensive they are.

  • It was great!

    I could get rid of a lot of "extra" cords. I can just keep one usb c and charge my phone, my mouse, and headphones with one cord. Shoot, I can even charge my controllers now too. I like that they're becoming like outlets. Like, this is just how you get power to the device(S). Without searching for the "right" cord all the time.

  • Not at all a game changer, for me.

    I mean, it's just another and one more type of cable. Sure, in theory it's simpler than many various cables and it's even less stupid than the previous USB types, but it's still a mess.

    At least, for non-geek me, those cables are a mess as I need to be able to distinguish between the exact same cable to find which one is USB-C or Thunderbolt, between the various versions of USB-C itself, and then between USB-C that comes with or without power delivery, and with what power limitation? And then, despite USB-C supposedly being a standard there are still too many cables that just won't work with certain devices because reasons.

    Add to that the many USB-C docks (and dongles) that work... more or less reliably and more or less as marketed (even more so under Linux, but those issues exist under Mac and under Windows as well).

    Older cables and ports were cumbersome, and thick and whatever but, as far as I'm concerned, for the most part they just worked like they were supposed to. And I never had an issue knowing which cable to plug into which port as they all looked, you know, different.

    Nowadays, I have to label each one of my USB-C cable with some masking tape so I can identify it in a glimpse without wasting my time trying them all one by one.

    Edit: some clarifications.

  • I certainly like it better, it's an improvement, but "game changer" is strong. I'm slowly replacing gadgets to USB C through attrition. The charge port has ceased to be the failure point for any of the gadgets I own. My pile of spare cables is still excessive, but moving further back in my storage closet because I need them less and less.

  • Well, for me, the selling points are:

    • Versus earlier versions of USB, it's reversible. This isn't a game changer, I guess, but it's definitely nice to not have to fiddle plugs around all the time.
    • I don't know if it's the only form of USB that does USB PD -- I'd guess not -- but in practice, it seems to be pretty strongly associated with USB PD. Having USB PD isn't essential, but it makes charging larger devices, like laptops, a lot more practical. I can lug around a power station that doesn't need to have an embedded inverter.

    I still feel that it's kind of physically small and weak compared to USB A. That's an okay tradeoff for small portable devices that don't have the space for larger connectors, but I'm kinda not enthralled about it on desktop. I worry more about bending connectors (and I have bent them before).

    So for me, I'd say that it's definitely nice, but not really in a game changing sense. I could do the things it can do in somewhat-worse ways prior to USB-C.

  • Except maybe some devices (like IoT) that are powered up by an always plugged micro-usb, my cellphone is USB-C for a long time now, and my laptop has 3 USB-C/TB (no A), so it's easier for a couple of stuff. But I have a usb-c hub with multiple USB-A outlet because I still have a couple of devices to plug like keyboard, trackball, webcam, headset, UPS, FTDI stuff, etc.

    No more micro-USB plugging/unplugging for phones.

    The prob with usb-c is mainly for powering hungry devices, you need 60W cable, 100W cable, 240W cable, etc.

    • JSAUX makes a great 240W cable that’s fairly priced and has 240W printed on the ends. It’s stiff but that’s because it’s actually gauged for 240W. I just decided to buy those in blue for anything that required more watts than mobile devices. Then I get at least 30W rated cables in red for all the mobile stuff. Super easy to know which is which at a glance.

      • I get my 60w and 100w cable at Ikea, they meet world standards and I trust them.

  • The good things:

    • It really is an advantage over normal USB, that I don't have to trun the plug three times while trying to connect it, as it can be plugged in either way.
    • I find the extra protection also cool, so in case you accidentally try to plug in something you are not supposed to, it just simply won't work instead of, I don't know, supplying too high voltage or something.

    So far it caused a lot of headaches though:

    • Way too often I found myself in a situation, where I couldn't use some devices, because I didn't have the necessary adapter. This issue should be temporary though, so I'm not complaining.
    • Some cables are not compatible with some devices, and it can be really confusing. Before I knew this, I was certain that a monitor and a laptop of mine weren't compatible for a long time, until someday I read about this and tried it again with a different cable.
    • In most cases this is not an issue, but rarely I find that the USB type-c plug is not as robust as a micro USB for example. On my girlfriend's Samsung S8 it always slipped out, so the contact was terrible, while a micro USB plug does have some clamps to properly attach. Again, in most cases the type-c plug is clicking in properly, so it's not an acute problem.
170 comments