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novetan

macrumors 6502
Original poster
Sep 3, 2010
398
10
I intend to buy a 30W power adaptor (see image). I know a 30W power adaptor will not charged more than what the iphone can receive at 20W as it will self regulate (this what I hv read). I intentionally buy a higher wattage for future proofing.

Which option will charge faster. Option 1 (A to C) or 2 (C to C) assuming both charging cables are of same quality. Does USB Type A 2.0 or 3.0 make a difference as it is not stated in the product. Or it hv no effect as this is not for transferring data. Sorry I'm quite noob in this.

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DarkPremiumCho

macrumors 6502
Mar 2, 2023
266
176
Opt for the C to C option, as long as it supports USB-PD, even though it may not offer faster charging.

The A to C option often requires non-standard modifications to the cable or port to achieve that wattage.
 

novetan

macrumors 6502
Original poster
Sep 3, 2010
398
10
Opt for the C to C option, as long as it supports USB-PD, even though it may not offer faster charging.

The A to C option often requires non-standard modifications to the cable or port to achieve that wattage.
Hmm, what you mean in your 2nd para. A to C cables are readily available in the market. In my hand I already hv a few A to C but not C to C. Hence my question here and if C to C is charging faster I will go buy one. It don't cost much anyway but i also want to know academically. Need to catch up with some techie stuff knowledge.
 

iStorm

macrumors 68000
Sep 18, 2012
1,847
2,257
Hmm, what you mean in your 2nd para. A to C cables are readily available in the market. In my hand I already hv a few A to C but not C to C. Hence my question here and if C to C is charging faster I will go buy one. It don't cost much anyway but i also want to know academically. Need to catch up with some techie stuff knowledge.
Charging using USB-A is typically limited to 12 watts, even if you use a USB-A to USB-C cable. That's just the standard spec for USB-A (max 5 volts * max 2.4 amps).

Supposedly this one has QuickCharge 3.0 for more wattage/faster charging using USB-A, but iPhones don't support QuickCharge so it'll charge slower. Only devices that support QuickCharge will charge faster.

It looks like this is just a cheap charger from AliExpress with hardly any technical information listed, so who knows what it's actually doing. Personally, I would stick to well known/trusted brands.
 

novetan

macrumors 6502
Original poster
Sep 3, 2010
398
10
Charging using USB-A is typically limited to 12 watts, even if you use a USB-A to USB-C cable. That's just the standard spec for USB-A (max 5 volts * max 2.4 amps).

Supposedly this one has QuickCharge 3.0 for more wattage/faster charging using USB-A, but iPhones don't support QuickCharge so it'll charge slower. Only devices that support QuickCharge will charge faster.

It looks like this is just a cheap charger from AliExpress with hardly any technical information listed, so who knows what it's actually doing. Personally, I would stick to well known/trusted brands.
Tks for reply.

Sorry, don't understand what you mean iPhones don't support quick charge. If we charge the phone using a 5W adaptor against a 20W adaptor, we will see a big diff right? Am I missing something? What is exactly QuickCharge?
 

iStorm

macrumors 68000
Sep 18, 2012
1,847
2,257
Tks for reply.

Sorry, don't understand what you mean iPhones don't support quick charge. If we charge the phone using a 5W adaptor against a 20W adaptor, we will see a big diff right? Am I missing something? What is exactly QuickCharge?
Quick Charge is a technology developed by Qualcomm to get past the 12W limit that USB-A has. To make use of it, the device you're charging also needs to support it. Apple Devices do not support Quick Charge, so they just use the standard/slow speed when using a USB-A charger.

If you were to charge your iPhone using the USB-A port on this charger, it's only going to charge at 12W or less. To get more wattage to charge faster, you need to use a USB-C charger.
 
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novetan

macrumors 6502
Original poster
Sep 3, 2010
398
10
Quick Charge is a technology developed by Qualcomm to get past the 12W limit that USB-A has. To make use of it, the device you're charging also needs to support it. Apple Devices do not support Quick Charge, so they just use the standard/slow speed when using a USB-A charger.

If you were to charge your iPhone using the USB-A port on this charger, it's only going to charge at 12W or less. To get more wattage to charge faster, you need to use a USB-C charger.
ah ok I think I get it.

So even though the power adaptor has two ports, a USB A and USB C rated at 30W, the A will only gives out 12W whereas the C will gives out 30W but iphone 15 will not receive 30W anyway but at 20W as it regulates itself at 20W limit. Is that correct just to confirmed my understanding?
 

iStorm

macrumors 68000
Sep 18, 2012
1,847
2,257
Yeah, pretty much. Couple things though…

The 30 watts is most likely shared between the three ports. If you charge two things at once, the wattage could be split into something like 12W over USB-A and 18W over USB-C. Again, there's no technical information listed, so we don't know for sure how this particular charger is handling it.

Also, the iPhone 15 actually accepts up to 27W of power. 20W is just the common/basic charger Apple sells.
 
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novetan

macrumors 6502
Original poster
Sep 3, 2010
398
10
Yeah, pretty much. Couple things though…

The 30 watts is most likely shared between the three ports. If you charge two things at once, the wattage could be split into something like 12W over USB-A and 18W over USB-C. Again, there's no technical information listed, so we don't know for sure how this particular charger is handling it.

Also, the iPhone 15 actually accepts up to 27W of power. 20W is just the common/basic charger Apple sells.
Thank you very much for all the info. Very in depth !!
 
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