24W over 2 USB ports

Hey, just a quick question.
I bought an ANKER charger with 2 USB ports a while back and I have a general inquiry since then.
It advertises 24W charging. Now does that mean 24W over each port, or 24W split up over 2 ports, so 12W per port?
Do I need to worry about charging my phone? (which only supports up to 18W charging)

Hi @Konstantinos_Stergio,
Generally, it means 12W per ports. This is because the “standard” USB charging specification maxes out at 5V 2.4A per USB port (5V * 2.4A = 12W).

You don’t need to worry about sending too much power to your phone as there is a bit of a handshake process that occurs when you connect the device (“Hey, can you charge at 5W? What about 10W? How about 12W? OK, here you go!”). Generally, your device will only accept as much power as it needs.

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When you look at portable chargers they more or less play with the numbers in different ways

  1. Total watts, if you’re lucky they tell you the total # of watts the device can ouptut. To get the most out of each USB A (the fat square port) you’d need to get 10 W per port

  2. Total current. So you might run into weird things like a 4 port charger, advertises 2.4A per port, but has a TOTAL CURRENT of 5A. So say your charger has 4 ports, you can plug in 2 devices and get max current (2.4A x 2 ports) or you plug everything in and get only 1 A per port (1A x 4 ports). Kinda sneaky!!

  3. The only way to get 18W charging is to get usb-C PD (Power delivery)