i mean sure if you hook up 20v to old nokia 5v 200mah charger... you are gonna see dead phone or lot of heat and angry phone

also is there yet even devices what give out 20v

few years ago afaik there was none really

https://www.onsemi.com/pub/Collateral/NCP4371-D.PDF

heres a quick charge controller that can do 20v

Figure 17. NCP4371 State Diagram shows the request part

https://www.engineering.com/ElectronicsDesign/ElectronicsDesignArticles/ArticleID/17584/Challenges-in-Making-a-Fast-Charging-Battery.aspx#

```Batteries Must Be Specifically Designed to Withstand Fast Charging

A battery is a sensitive electrochemical device. Many factors can damage the battery: temperature, sudden discharging/charging, too many charging cycles, etc. The battery is designed to absorb a specific amount of energy in a specific amount of time, and pushing more energy into it than it can handle damages the battery and shortens its lifespan. In the case of the most commonly used lithium-ion (Li-Ion) batteries, doing this causes lithium plating to form on the anode, which creates dendrites and shortens the battery life.```

@vague phone batteries are single cells in series

there's never going more than 4.2v into a battery

if there was they'd run the risk of exploding

so the current has to vary then

the only reason for the higher voltage is less loss in the cable

in order for more power to go in to the battery you have to increase atleast one of voltage and current. you keep saying the voltage is constant so the current has to change for the charger to put out all these different watt ratings

https://www.electronics-notes.com/articles/electronic_components/battery-technology/li-ion-lithium-ion-charging.php
https://www.microchip.com/stellent/groups/designcenter_sg/documents/market_communication/en028061.pdf

it looks like varying current is how its done

https://www.androidauthority.com/fast-charging-explained-889780/

> Fast charging at high voltage?
section explains that it does step down the voltage to increase the current

you can't increase voltage, it's not safe

```The diagram above shows how MediaTek’s PumpExpress 3.0 and 4.0 manage to reach up to 5A of charging current. If a 5A cable is connected, its technology bypasses the conventional switching charger to enable a higher current. In this case, the circuit negotiates the required voltage over the data lines, raising and lowering the Vbus charging voltage for maximum efficiency.```
i could fucking write a report on this

you can't increase current, it's limited by the batteries internal resistance and safety

all of these sources show that phones that support quick charging have batteries that support higher currents aswell

yes, that's the power going into the phone, and it slightly increases charging current for the battery

it increases it quite a lot

in that one case up to 5A

that's what's going into the phone

pre losses

- what the phone is actually drawing

in order for quick charge to charge a battery faster more power has to enter the battery. power can only exist as voltage and current. we've established that batteries are charged at a very specific voltage and that the current the battery sees varies with respect to the battery voltage

https://cdn57.androidauthority.net/wp-content/uploads/2018/07/Battery-Charge-Voltage-vs-Time.png

batteries are not charged at a specific voltage

it depends how discharged they are

the more discharged a battery is, the more current it wants to draw and it's limited by lowering the voltage

as it gets charged the voltage climbs to ~4.2V and current drops

yessss

it's still wrong of linus to say you're charging at 14.5V

you're not

its technically correct if you only consider the power going into the *phone* since thats how the quick charge standard works

let me look at the links you posted

the first one has nothing to do with charging

that's a datasheet for a quickcharge controller