Why is USB charging so useless?

[crossmr]

Plugged into the adapter, the battery charges quickly like a champ. 1 % every minute or two.

On USB it often either gains nothing or actually loses battery just sitting there. There have been times I've had my phone plugged into USB for an hour or two while I was busy doing something, come back and checked it and found it to be 4% less then when I plugged it in (no active programs, e.g. video player, etc) just sitting there, standby.

Half the time when it does gain power it's stupidly slow. in the last 2 hours my S3, mostly sitting there except for about 3 text messages gained around 3%.

It's always been bad but it seems worse lately, and all the excuses I heard when i first bought it never added up to me. I know my iphone 4 used to have no problem charging up on battery and this is just ridiculous.

 

[girolez]

Hi

Its because a standard USB port on a PC/laptop has a max current output of 0.5 amps at 5 volts. This is sometimes less than a phone is using when on. Wall chargers supplied with phones provide 1amp, 2amps or even 3amps at 5volts sothey charge the devices much quicker and can charge them up when in use. Whenever you can use a high output (ampage) charger, it wont harm a phone and will charge it up as fast as its able to accept charge.

Roger

 

[crossmr]

Hi

Its because a standard USB port on a PC/laptop has a max current output of 0.5 amps at 5 volts. This is sometimes less than a phone is using when on. Wall chargers supplied with phones provide 1amp, 2amps or even 3amps at 5volts sothey charge the devices much quicker and can charge them up when in use. Whenever you can use a high output (ampage) charger, it wont harm a phone and will charge it up as fast as its able to accept charge.

Roger

I've had this a couple years. It never used to be like this. It was slow, but it never used to lose charge while just sitting there idling.

 

[girolez]

Hi

It may be the start of a failing battery. They do go quite suddenly, so if it quickly seems to get worse, thats probably the reason.

Roger

 

[Fatstogey]

asus motherboards charge faster on usb 3.0

 

[Rxpert83]

Simply could also be that your phone is using higher battery than normal.

Rogue app, low signal, background syncing ect

 

[svim]

USB 2.0 ports provide 5 volts/0.5 amps but newer computers often have USB 3.0, which will supply 5 volts/0.9 amps.

Are you plugging your phone directly into a USB port on your desktop/laptop or are you just using an open port on some peripheral like a keyboard's USB port? A lot of Macs have USB ports on the keyboard but not that those ports are not going to provide you with the same amperage. They're fine for things like flash drives but not powered devices.
If you're using a USB hub, if it's just a low-end one that relies solely on whatever power the port it's plugged into, you need to get a powered USB hub (comes with its own power adapter).
Also, if your desktop/laptop is in sleep mode or hibernation mode, there's a good chance the USB ports are also dormant. A number of desktops do keep power to USB ports whether they're in use or sleeping but a lot do not. A lot of newer laptops have one or more USB ports that are left powered if the laptop is on or off but it varies.

 

[mydian]

I don't do it very often but it takes around 5 hours to charge my phone from dead to full with USB. Something is wrong with your setup.. be it the phone itself, charging port, usb port on the computer, or the cable. It pretty much takes twice as long to charge the phone via usb vs. AC adapter. Your phone's behavior is not normal.

 

[Stuntman]

I've had this a couple years. It never used to be like this. It was slow, but it never used to lose charge while just sitting there idling.

Hi

It may be the start of a failing battery. They do go quite suddenly, so if it quickly seems to get worse, thats probably the reason.

Roger

It's possible the battery is failing. My old phone started to have problems charging and holding a charge. You may want to check whether or not the battery is getting fatter. That's what happened to my old battery. It started to buldge when I noticed it wasn't holding a charge or wasn't charging well.