Can i use 18w Or 20w for my iphone xs max?
Can i use 18 or 20W charger for i phone xs max?
iPhone XS Max, iOS 14
ProustGiulio wrote:
Yes, you can, along with an appropriate Lightning to USB-C cable.
The charger doesn’t “push” power; it just supplies the power “drawn” by the device.
Regards
Giulio
They're current limited voltage sources, but it more or less a fixed voltage. However, with USB-C with USB Power Delivery it gets a little bit more complicated because it can supply different voltages and needs some way to negotiate what voltage to provide.
This article actually mentions charging an XS with an 18W (iPad Pro) power adapter and either an Apple or aftermarket USB-C to Lightning cable. They used some sort of test setup to monitor the voltage and current.
https://gtrusted.com/what-happens-when-you-use-the-original-apple-usb-c-to-lightning-cable-versus-a-alternative-cable-option-to-charge-your-apple-iphone-xs-max
First we used the Apple USB-C to Lightning Cable to connect the Apple iPhone XS Max with the Apple 18W USB-C Power Adapter that shipped with the Apple 11-inch iPad Pro (2018). Over USB Power Delivery negotiation, we could see in the first few seconds after plugin no current was pulled at a 5 volts rail startup voltage. The iPhone only began pulling current when reaching 10 seconds to initially charge to around 7.6 watts (5.1 volts @ 1.5 amps). After a couple hard resets later the voltage went up to a 9 volts rail while current was pulled in between 1.8-2.1 amps to achieve max charging at around 18.9 watts (9 volts @ 2.1 amps).
By replacing the Apple cable with the SensusTech USB-C to Lightning Charging Cable, we also observed a similar trend over USB Power Delivery where current was only pulled a bit later after plugin for about 10.2 watts (5.1 volts @ 2 amps) initial charging. After a hard reset however the voltage only stayed within 5V while the iPhone was charging at mostly around 11.7 watts (5.1 volts @ 2.3 amps).
