After a long day of nerding on fedi about new chargers that can handle 160W charging in a really small casing I decided to write down some general purpose.. things about how electricity works. Since I've done some explanations to some people and they said they found that info very useful here something made for people not good at math and without a degree in electronics engineering.
I will try to explain everything in simpel terms and with analogies, but the last time I done the math was six years ago during my A-Level exams, so any more educated person is free to weight in, just write me on a Platform of your choosing.
Whats a Watt
When looking at a charger or power supply, or talking about what comes out of a power socket, you will have seen or heard about Volts and Amps and Watts but how does this all go together. Well, basically, W is just V times A, and if you are in the EU your socket always gives you 230V. Doing simple math that means if you want 230W to, for example, charge your laptop really fast, just draw 1A right?
Well, basically yes, but it's not quite that simple. First, there is AC and DC, AC stands for Alternating Current, meaning it oscillates. Direct Current gives you the power straight forward, without any oscillation. But what is meant by Osculation?
If we come back to the basic physics of “Work”, there is two ways you can transfer energy with electrons. The straight forward one is just letting them flow, like water down a river, that is DC. The other way one can use it is by pushing and pulling it back and forth, imagine two groups of people pulling on a rope, alternating-ly. In our analogy, you could for example hook up a saw to the middle of the rope, put a log of wood underneath it and through the power of our two groups pulling on the rope repeatedly energy is transferred to the saw, cutting the wood over time.
As you can imagine, these two sets of ways to transfer electricity have different use-cases. You can't attach a saw to a river, and you can't expect a log of wood to be cut by throwing it into a river. So sometimes you need one or the other, and the way they are produced is also different.
Take a battery, when drawing power from it, it flows from one pole to the other, so you get DC. When you generate power using a generator, because of it's rotary nature, you get AC. Why? Because inside the generator is a rotating magnet that turns and through clever engineering switches it's magnetic field direction back and forth using that motion, thus pulling the electrons in it's wires back and forth, like our two groups pulling that rope. Historically, AC is easier to transport over long distances, that's why it's used everywhere and why the power out of your socket will most likely be 230V AC at 50hz, if you are European.
Now, as you can imagine, with this comes some complication. Your earlier mentioned laptop has a build in battery, but when charging you use the power from the wall.. so what gives? Well, basically the big brick on your laptop cable that says like “65W” converts the wall 230V AC to 12V DC for example. Given our earlier info that W=V*A, we can now deduce in order for those 65W, at 12V we need to draw 5.42A.
You may be wondering now, why go down to 12V? Why not go full in on those 230V that come from the wall? Well, you can. But not for long. Car batteries for example, are made to be charged at much higher voltage and wattage, especially when made to fast-charge. It all comes down to the materials used and how much of it. The thinner a copper wire is, the more electrons have to flow through the same area for the same charge parameters, and that creates heat. There is only so much voltage, for only so long, you can put on a given wire until it starts to melt. The wires in a big car battery are pretty thick, because the car has the space, but what's the point in putting big wires inside your laptop? You likely don't have a choice than to use a certain wire diameter, so your charging speed is gonna be limited by that.
Everyday Electronics
Now, knowing that you might have some questions. Have you ever plugged in your modern phone into your laptop charger? After all when they use USB-C it's fine right? Or were you too scared to do it?
No matter which of these two you were, your instincts were correct.
If you would put the full 65W at 12V into your phone, that's like 12V or even just 5V, you would melt everything inside of it and probably explode the battery. But thankfully! Since engineers recognize that “can plug in, so people will do it” these USB-C ports are a bit more clever than that. Or rather, the power bricks, the big rectangles in the power supplies like the laptop charger, are smarter than that.
Since many different devices need different Watts and Volts, there are protocols for the chargers and the devices to negotiate what one needs from the other or what they can handle. Failing that, the charger will just default to it's lowest output, like 5V 0.5A, that rarely does damage, or it might refuse to charge at all. Apart from that there are sadly vendor specific fast-charge protocols, like at least Samsung and Apple have their own, that a charger needs to support to fast-charge a phone of that maker, otherwise it just defaults to regular power. There is also something interesting I have with my phone, a Huawei P40. Besides fast charge, it also has “quick charge” when it is plugged into a high Watt cable like my laptop charger. It's charging faster than without it, but not as fast as with a fast charger from the “proper” Huawei charging cable.
It also gets really warm…
Now, for the ones in the known, and to come back to the fedi infodump I did around chargers (that at the time of editing is like 3 months old), there is an interesting phenomenon with Framework Laptops. The big model seems to support 240W for charging, but it only chips with a 180W charger, why is that? Worse, when it's in performance mode and under load, the 180W isn't enough to charge it, it can just keep it alive longer.
Well, USB-C might allow for 240W, problem is, getting components capable of handling that. The reason the Framework charger does 180W is because it supports the appropriate USB DP 3.1 EPR standard, which specifies 36V/5A. If you want to read more in-depth stuff they actually wrote an article about it: https://frame.work/de/en/blog/framework-laptop-16-deep-dive---180w-power-adapter. There is a standard for 240W too, but it would make the charger significantly bigger and less efficient, and Framework wanted to be sustainable, thus you can opt to get a charger yourself.
Why Daisy Chaining Power Bars is “Bad”
On the topic of chargers, one has to discuss the often warned about daisy chaining of power bars. A normal phase in a residential house has a limit. Not only the Watts the entire house can draw, but the Amps the phase can do. Basically, if you draw too much power out of a single power socket, or rather on the same wire, you will blow a fuse. Breakers, at least in Germany, are rated for 16A usually, because once you go above that, in combination with 230V you draw too much power and start melting the wire in the walls.
Now knowing that, would you trip your breaker if you charged three Framework 16 laptops with 240V power supply? Possible actually, unless the chargers themselves mitigate this somehow, which I don't know if they do. However, power bars exist, why are they not a problem? Well, rarely tries anyone to charge their three super power hungry laptop on the same power bar, and also these are very new. But the thing is, even phones could go over the limit. It's not uncommon to have a charger draw 2A, so 8 of them on the same socket would reach the limit as well. Luckily, most power bars go up to only 6 sockets, and who tries to charge that many phones on one bar anyway, right?
Well, now imagine one only has one convenient socket, and they thus daisy chain power bars in order to reach all their devices, the TV, the gaming computer, the router, the phone charger at their couch, the AC, maybe some lights. Now they plug in their framework at one of these, and the light goes out.
This is the reason daisy chaining power bars is discouraged. There is actually nothing wrong daisy chaining them per se, the actual problem is you are very likely to overload the socket. If you are aware on how much power you are drawing on a given daisy chain, you are fine. Professionals, and me as well, daisy chain them all the time, but we keep two things in mind doing it: The power budget (don't go over the e.g. 16A, x Watts of the phase) and the starting current.
Capacitors and Power Outages
For this one, let's go into some more demanding tech, Power Suply Units. A modern PSU in a modern Computer might draw up to 1000W, even more if you have a recent high end graphics card. Such a PSU does not simply plug those watts into all the components inside of your Computer. It instead transforms the Watts and Volts down to different levels that are needed by different parts inside. A fan needs much less Volts than a GPU, or a Motherboard. Apart from that it also does a variety of correction and “cleaning” to the power in order to make it nice and stable for the individual, often fragile, parts, as well as maximize it's efficiency so your power bill doesn't get too high.
In order to transform power and to “clean it”, you need a lot of capacitors and copper coils. Those cost quite some money, so high power PSUs and very efficient ones at that cost a lot of money, but what do they do exactly?.
A capacitor is basically a very volatile mini-battery, it takes up charge up to a limit before it transmits it, this is extremely useful for many many applications. This can be used to smooth out the supplied power for example, and other various effects. But it has two side effects: they can take a long time to discharge, and they draw a lot more power when not charged.
The first one is the reason no one should ever open up a PSU, you can unplug it, unscrew it, take it out of the PC, put it on your desk, open the box, accidentally take your screwdriver to one of the capacitors and get flung through the room, because it was still holding an insane, very deadly, amount of power.
The second one is important for when it was out of power for a long time or had been professionally discharged. Being a responsible and money savvy person, you might have one of these power bars that can be turned off so your devices don't draw power passively. When you do that, and it stays off for a night, the capacitors in the PSU will be very discharged. Now, if you turn on your power bar again, that PSU will in the first moments draw much much more power than it's 1000W that it's rated for. The Capacitors will be “hungry” for power. So even if your power budget on your socket works out, turning it off and on again may trigger your breaker. When that happens you need to unplug some devices and turn the bar on, then plug them back in one after another. Them combined will just draw too much power when turned on at the same time.
You might think that's unlikely to happen? Well, my desk has a NAS, my old gaming PC, and a Laptop dock capable of drawing 400W. Due to spacial constraints, next to my desk is my girlfriends desk with her gaming PC, and due to these constraints we had to daisy chain two power bars to plug them both in. Whenever I want to turn mine back on, I have to unplug the laptop dock, otherwise I will turn of the light in the living room until I moved the Wardrobe in the neighboring room to reach the power panel of the apartment. This has happened a couple of times.
Phases and Rooms
Now, with all this knowledge, you might be wondering “But I have x computers and stuff at home, and that doesn't cause issues, why can three laptops in a power bar trigger a break but three PCs in my house don't”. For this, we need to come back to the previously mentioned phases.
When you look at your electric box, you will find not a single break, but many, often labelled by room, with one or two extra for the kitchen stove. That is because, your house doesn't run on a single phase, it runs on multiple, each individually being able to handle e.g. 16A. Usually, you want a phase per room, maybe two if it's a big room. For the Kitchen, the stove ideally has it's own breaker, which is different from the other ones, and that's because a regular stove doesn't use one phase it uses two.
The math behind it is not very easy, and actually ruined quite some grades in my class when we had our energy engineering lecture, but basically if you take two phases who's phases are not identical, but have an offset (120° to be precise), you can leverage some fancy engineering to effectively combine their power output. Instead of the individual 230V you will now get 400V, and a lot more Amps. A stove, as it does a lot of heating, needs a lot of power and high voltage which is why it needs those two phases (or why yours, if it doesn't have those, takes ages to heat up).
You may be wondering, why we don't do that everywhere, since it gives much more power. You could charge as many Frameworks in a room as you please right? Well, as mentioned, it needs clever engineering. Leveraging complex current is a lot more difficult and needs more work to make work, so since apart from a stove nothing really needs it in a standard issue home, why bother. Converting 400V AC to DC is also a lot more complex, and has the potential to create a lot more heat, hence useful in a stove but not in a laptop charger.
Also, while 230V are already rated as “don't touch, can kill you”, two phase power is more a “it will kill you” affair, something you don't really want exposed to the average layperson. Industrial buildings actually often have complex power everywhere, since many big machines need it, but they also have their own big boy connector, not comparable to the little Schuko plug of your run-of-the-mill laptop charger.
Addendum: Why Phases and What Does A Generator Do
Having read all of this, let's be a little bit more technical here in the end, if you are interested. As I mentioned previously, the rotary nature of a generator causes AC and there is also something about phases and 120°, what is all that about really.
Well, first you could compare a phase in a wire like a wave of sound in the air. A regular phase as used for electrical power is basically a sine wave running at a specific amplitude and frequency, so the power constantly goes up and down at a specific rate per second because the electrons are pulled back and forth -230V to 230V. Actually, 230V is not exactly what's running through a wire, it's more the.. effective average, it actually peaks around 310V.
In order to convert it to DC you can for example use a diode, which let's the power through in only one direction, so you cut out the bottom part of the sine wave, 0 to 310V instead of -310V to 310V, effectively giving you 230VDC. This of course throws away at least half the power, but there are clever sequences of parts and multiple diodes devices employ in order to minimize that loss and not brutally cut away half the power transmitted, hence why a PSU is so complicated. Without that something like 80-plus platinum wouldn't exist.
Now, if you want two phases, you take two wires and offset their sine waves, as mentioned by 120°. If you combine those two, instead of just averaging out, they add together. The previously mentioned 230V average, with the offset and the combined phases, works out to about 400V. I could look up the math again but let's not do that to ourselves (and not give me nightmares of complex numbers and resistances again).
All of this comes together at the source, the generator. A big boy generator, as used in a Hydro- or Nuclear Power Plant will give you three phases, all offset perfectly at 120°. Why? In it is a rotor, and the stator, some parts familiar to you if you played Satisfactory, they together make up a motor. Basically, a motor and a generator are the same thing, the only difference is if you put kinetic power into the rotor by twisting it, or if you pump electricity into the stator, one will be converted to the other. Inside of these parts is a strong magnets and some coils. If you had some more advanced physics classes, you will know two fundamental laws of electromagnetism: if you move a wire past a magnet it will create a current, and if you electrify a wire it will create a magnetic field. This is what we leverage here. If the rotor moves, it's magnets will cause a current in the stator, which creates your electricity. If you put power into the stator, it's magnetic fields will push the rotor and cause it to spin.
But why does the power out of a generator alternate? As you turn the magnet inside the rotor, you also turn it's associated magnetic field, at one moment it goes into the one direction, 180° later into the other, and with that the direction of the current changes as well. The electrons in the wire are pushed back and forth, generating our sine wave and AC power. And now, if you put exactly three coil-units into the stator, each offset by equal amounts around the rotor, they will be offset 120° in space, and so will be the sine waves in each wire connected to these coils. Funny how the physical dimensions translate into the wave form here. Why three? This is the most efficient configuration and gives us these very useful phases that we can use for simple and complex power, or that's what my electronics classes told me anyway.
Conclusion
Power, it's simple and complicated. Many of us are not educated on anything about it and I feel that's a shame. Maybe this little article (oh god why is it so long) gives you some things useful to your.. maybe not every day, but every other week, life.
Have an energetic day