From the perspective of the portable battery, there’s only one port available.
In that port I can only input USB cables, and some of them will provide power, others will take power.
In essence how does the battery know which one to do?
I’m assuming it has to do with how the input behaves, like “one pushes harder than the other”, but in some cases it’s not as clear to me.
If I plug a phone on my laptop, the phone will charge. But if I put a portable battery, the laptop will charge?
I’m sure there’s some ambiguity but I’m very curious on the details and ideally a little more than a “like I’m 5 answer” 😀
Comments
The usb c standard includes simple communication between devices, so a wall charger tells the other one “I can only charge you”
A phone tells the laptop “I’m a small battery device, I think you should charge me”
Essentially usb devices are configured in software to either be sources of power or sinks(receive power), or both they communicate this so each other when plugged in.
Some devices like phones can be configured to be either by the user, so you can choose to send power from your phone.
In the case of batteries, they’ll try to automatically pick the right option depending on that they are talking to.
Usually if you plug two batteries together they won’t do anything. Same as if you plug two wall chargers together.
Easy, USB cords are charging and information exchanging cords. When you plug in the charger the charger gives power and also a little signal saying I AM A CHARGER, and when you plug in your phone it gives a signal saying I AM A PHONE, BLAH BLAH BLAH, I TAKE THIS MUCH POWER TO CHARGE MY BATTERY which is the part your power bank cares about.
The devices will communicate with one another and determine which one should be charged and which one should do the charging. Sometimes you can control this, sometimes you can’t
When you connect two devices like a battery and a phone via an USB-C cable they start to talk to each other over the data lines in the cable. After they communicated themself as battery and phone, the battery will start supplying power.
They even negotiate what kind of voltage the receiver (phone in this case) can handle and the battery will set the appropriate charging mode and voltage to charge the phone at best speed.
If I were to programme it, I’d reserve certain channels for sending power (either direction), but there’d be a communications channel dedicated to inform whoever is listening that power is flowing in a certain direction (A to B).
So plug into wall outlet, wall is ‘always on’ in one direction.
But plug into computer port, negotiation has to occur. It would have to be something programmed into the powerpack logic that indicates “if not receiving, send” or something to that effect.
The USB Type C connector isn’t just a conector. A Type A connector is a… Let’s call it “master side device” a Type B is a “slave side device”, same goes for micro and mini and others.
Type C includes in it’s protocol, the ability for devices to talk and show specifications and abilities of the connected device and the cable itself (yes, the cable has a chip). So they talk to each other and the controller decides who charges who and at which rate and other details about the connection between them.