Usb chargers: how many amps is delivered?
Apr 27, 2014, 12:59 am
#1
Original Poster
Join Date: Feb 2013
Posts: 356
Usb chargers: how many amps is delivered?
I've got two usb chargers (which plug into a wall socket): one is a 2 port and another 4 port.
The 2 ports one is rated as 5V and 1A.
Does that mean that when I plug in a single device (only one port is used) that device will receive the full 1A? or is it still 0.5A for that single port?
Same question goes with the 4 ports one. Its rated 5V and 2A.
So will the current delivered look like this:
3 ports used: 2/3A per port
2 ports used: 1A per port
1 port used: 2A for that port
Or will each port still receive an 0.5A, irrespective of how many ports are being used?
TIA
The 2 ports one is rated as 5V and 1A.
Does that mean that when I plug in a single device (only one port is used) that device will receive the full 1A? or is it still 0.5A for that single port?
Same question goes with the 4 ports one. Its rated 5V and 2A.
So will the current delivered look like this:
3 ports used: 2/3A per port
2 ports used: 1A per port
1 port used: 2A for that port
Or will each port still receive an 0.5A, irrespective of how many ports are being used?
TIA
Last edited by mzzxx11; Apr 27, 2014 at 1:33 am
Apr 27, 2014, 11:14 am
#3
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The original USB specifications for PC specified 5V with a max of 0.5A to avoid frying peripherals. Nowadays, if some devices or cables signal ability to use more amps, the charger will deliver more, like 1A or 2A. But some chargers will deliver no more than 0.5A per port regardless.
So both unclear whether your USB chargers are designed to detect and deliver more than 0.5A per port ever, and if it is capable, how much it will divide it's total capacity across the ports. But for sure, if it says it's total capacity is 2A, it will never deliver more than that to all ports combined.
So both unclear whether your USB chargers are designed to detect and deliver more than 0.5A per port ever, and if it is capable, how much it will divide it's total capacity across the ports. But for sure, if it says it's total capacity is 2A, it will never deliver more than that to all ports combined.
Apr 28, 2014, 7:08 am
#4
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Most of the multi-port chargers I've encountered are crap, in that they deliver .5amp per port, regardless of how many ports are in use.
Then there are a few doubles which are semi-crap, in that they will deliver .5amp to each port if all ports are in use, but will deliver 1amp to ONE of the ports if the other port is not in use - but it's usually a specific port (i.e. left port is 1amp but only if right port is not in use, right port will be .5amp no matter what).
If your double will actually deliver 1amp to one of the ports, it will most probably have a "1amp" marking which indicates which of the two ports is capable of 1amp. If it doesn't have that marking, then most likely it's a 1amp total model, meaning each port is only capable of .5amp even if the other is not in use.
The easiest way to check is to plug in a high-consumption device that won't charge unless the charger delivers 1amp. If it charges, your port is 1amp. If not, it's .5amp.
Then there are a few doubles which are semi-crap, in that they will deliver .5amp to each port if all ports are in use, but will deliver 1amp to ONE of the ports if the other port is not in use - but it's usually a specific port (i.e. left port is 1amp but only if right port is not in use, right port will be .5amp no matter what).
If your double will actually deliver 1amp to one of the ports, it will most probably have a "1amp" marking which indicates which of the two ports is capable of 1amp. If it doesn't have that marking, then most likely it's a 1amp total model, meaning each port is only capable of .5amp even if the other is not in use.
The easiest way to check is to plug in a high-consumption device that won't charge unless the charger delivers 1amp. If it charges, your port is 1amp. If not, it's .5amp.
Apr 28, 2014, 7:14 am
#5
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Apr 28, 2014, 7:21 am
#6
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To make things more confusing, and more techincal, it also depends on what type of D+/D- shorting your phone expects to see. IOS devices expect the D+/D- to be shorted to +5v and GND through a voltage resistor divider... if the phone senses this configuration it will draw the full current available. Most Android devices require a direct connection between D+/D- to draw full current from the charger. So an Android device might only draw 0.5A from an iPhone/iPad charger, while an iPhone will draw 1A or 2A from the same charger, and vice-versa. This is why many multi-port chargers will lable certain ports as iPhone/iOS/iPad with it depending on the D+/D- configuration, not necessarily the port's max current.
This article isn't 100% applicable to the dual-charger subject, but it helps explain the D+/D- configuration differences. Also, if I'm going to trust anyone in regards to basic circuitry, it's going to be a HAM radio enthusiast.
That said, some Android phones are now smart enough to draw full current from either configuration (I know my Galaxy S4 can, not sure about others).
As far as dual-chargers you can trust, I've had really good luck with this PowerGen 3.4A dual charger from Amazon... It seemed to charge both my Galaxy S4 and Asus T100TA Windows 8.1 Tablet at rates similar to their OEM chargers when plugging the Asus into the "For Android" plug and the Galaxy S4 into the "For iDevice" plug (as counter-intuitive as that may seem). I've since replaced the Asus T100TA with a MS Surface Pro, so I use the 1A USB port on the SurfacePro's charger to charge my phone when traveling.
This article isn't 100% applicable to the dual-charger subject, but it helps explain the D+/D- configuration differences. Also, if I'm going to trust anyone in regards to basic circuitry, it's going to be a HAM radio enthusiast.
That said, some Android phones are now smart enough to draw full current from either configuration (I know my Galaxy S4 can, not sure about others).
As far as dual-chargers you can trust, I've had really good luck with this PowerGen 3.4A dual charger from Amazon... It seemed to charge both my Galaxy S4 and Asus T100TA Windows 8.1 Tablet at rates similar to their OEM chargers when plugging the Asus into the "For Android" plug and the Galaxy S4 into the "For iDevice" plug (as counter-intuitive as that may seem). I've since replaced the Asus T100TA with a MS Surface Pro, so I use the 1A USB port on the SurfacePro's charger to charge my phone when traveling.
Apr 28, 2014, 7:55 pm
#7
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my Anker 40W seems to charge full rate (up to 2.4A per port, on multiple ports) on both iOS devices (iPad3, iPad Mini, iPhone 4, iPhone 5) and Android (HTC one).
I wasn't able to test the current for the Android phone, but left it on and the charge rate seemed just as fast as on its dedicated charger.
I wasn't able to test the current for the Android phone, but left it on and the charge rate seemed just as fast as on its dedicated charger.