Powering/charging device from USB. How many amps?

[CZroe]

I have a Samsung YH-999 Portable Media Center. To get content onto it you must connect it to the PC using the USB cable and sync using Windows Media Player 10 or the Media Center application. The problem is that sometimes the sync process takes all night and the battery does not last that long! It does NOT have a dock/cradle like the Creative Zen Portable Media Center, which is otherwise inferior in every way. I understand that Li-Ion batteries are very delicate and I hear about 3rd party chargers and crap frying laptops and cell-phones all the time (By not having a "chip" that detects the battery charge level to know when to stop charging), but the "charger" included with the device is a simply Delta AC adapter (5v DC 3amp output).

USB ports output 5v, but what amperage? I only need 3amps so I can make my own USB2.0 charge/sync cable.

 

[corkyg]

USB Devices typically draw from 3 to 6 amps, and really should be minimized when on battery power. I run a full load of USB devices - about 4 of them, and a Firewire device, but always on A/C power, and even then, it cannot keep the main battery charged. It will lose about 1% every 4 hours.

For what you are describing, I would use a powered USB hub that provides its own power to your large device.

 

[MWink]

Originally posted by: corkyg
USB Devices typically draw from 3 to 6 amps, and really should be minimized when on battery power. I run a full load of USB devices - about 4 of them, and a Firewire device, but always on A/C power, and even then, it cannot keep the main battery charged. It will lose about 1% every 4 hours.

For what you are describing, I would use a powered USB hub that provides its own power to your large device.

Where did you get 3-6 amps from? USB ports are designed to put out a maximum of 500mA or .5A.

 

[corkyg]

Sorry - put a decimal in fron of those numbers - .3 to .6.

 

[CZroe]

Not enough amps, can't work. Exactly what I needed to know. Thanks!

 

[piroroadkill]

One of the reasons that FireWire is better...

 

[CZroe]

Idea! What about using multiple USB ports to charge it and one for interfacing with it? Or perhaps a medusa cable that connects to USB and Firewire for interface + charge. What are the specs for Firewire power output? BTW corkyg, it isn't for a laptop. The portable, battery-powered device is to be charged by a desktop to take content on the road using the device and eliminate the need for a laptop.