How long does it take to charge a dead batt on a USB charger?

[MMAfighterNH]

my batt is completely dead and i jus got my USB charger today, it been charging 4 almost 3hrs allready and light is still red..........but on my wall charger it only takes an hour, so do u kno how long it takes on a USB?

 

[Moonflame]

It took about 3 hours when I had my 901's (I now use a mod so I don't have to worry about USB charging ). If the light doesn't change soon I'd try using the battery anyway and see if it works. You may have gotten a dud light on your USB charger or you may have a dud charger.

 

[bearscreek]

Mine may actually take 3-4 hours, but I haven't timed it. I know it's a lot longer than with the wall charger. There's probably nothing wrong with yours.

 

[vpflueg]

I vape a mini M403 and my charge times are only about an hour or so with my usb charger. They take about twice as long with the wall charger.

 

[BARENETTED]

For me, the USB charger definitely takes longer than the wall.

 

[Porphy]

My charger is a US standard plug so I use the USB exclusively, it takes about 2 hours per battery. I have 4 universal USB chargers and 9 batteries though so I can keep them in a good rotation. (overkill, I know)

 

[Ellis]

That is exactly why i no longer use my USB charger. It just takes WAY to long.

 

[Zemrod]

My M403 takes slightly more than an hour to charge via usb. The M402 about 1.5 hrs. The wall charger seems to take longer, but I never timed it.

 

[Mr.B]

Took me about 2 hours for my small Blu

 

[Jim Davis]

The USB chargers will take longer because they output less power, but it's handy to have one as a backup.

 

[h8isgr8]

The USB chargers will take longer because they output less power, but it's handy to have one as a backup.

I think it's a little more complicated than that.

USB 2.0 specifies that unless the connected device identifies itself as a high-power device, that it will automatically be treated as a low power device with a max allowed current draw of 100mA (1-unit).

So even though a USB 2.0 port is capable of 500mA (5-units), unless there is active communication between the device and the host bus, then the full current capability will not be available.

Now, there is an expection to this though. If you are using a powered USB hub, then it treats all devices as high-power and will allow the full current amount available to any device.

When you plug the same USB charger into a 300mA wall adapter for example, then the full 300mA is available to the charging circuit. The wall adapter is a passive device that doesn't know or care about what is attached to it.

 

[Jim Davis]

I think it's a little more complicated than that.

USB 2.0 specifies that unless the connected device identifies itself as a high-power device, that it will automatically be treated as a low power device with a max allowed current draw of 100mA (1-unit).

So even though a USB 2.0 port is capable of 500mA (5-units), unless there is active communication between the device and the host bus, then the full current capability will not be available.

Now, there is an expection to this though. If you are using a powered USB hub, then it treats all devices as high-power and will allow the full current amount available to any device.

When you plug the same USB charger into a 300mA wall adapter for example, then the full 300mA is available to the charging circuit. The wall adapter is a passive device that doesn't know or care about what is attached to it.

Definately a factor.

My comment was just a simple explanation. I have 6 USB and 6 110v chargers. Most of the USB's label maximum output much less than the 110v's, and probably for the reasons you have mentioned.