Can it draw power from the usb cable when connected to a computer or do you always either need it to have batteries or be connected to the ac adapter?
1564647
I never installed batteries but as I recall it needs them or the AC power to operate.
15772
No, it does not come with an AC adapter. It is powered by the USB connection. I have had no problems with just using the USB connection as a power source.
1169292
It only draws current when a device is plugged in and using the USB power. You can leave USB cables plugged into the ports and the outlet will not draw current until those cables are connected to a device that attempts to use the USB power. (In theory a device could stop using the USB power once charged, and the outlet would no longer draw current, but very few devices are designed this way.)
1191296
The AC adaptor is not needed, it use the power from the USB3 which is adequate. However, it does have a mini DC plug that use 5 volts if you have to use the adaptor. I do not use this plug at all for this device or any other device that using the USB2 or USB3.
2191207
Yes, it does come with a USB cable (I think it's about 3' long). It doesn't come with an AC adapter, but as long as you plug it into the computer with the USB cable, it gets its power from the USB port.
145670
I use it only on my desktop or notebook. It need to be connected to a computer for scanning. It doesn't have built-in battery for operation. It doesn't require separate extra power connection. The USB connection to computer provide both power and data.
1243228
No batteries. It charges by plugging it into the USB port on a computer. (No data transfer...the USB connection is simply for charging.)
1554828
Yes, the USB charging circuit in this outlet does use power even when nothing is plugged in. I tested by wiring a Mastech MS8264 digital multimeter in series with the hot lead that powers the outlet. With nothing plugged into the outlet, the multimeter read 0.42-0.44 milliamps at 120VAC. Note that this is not a true-RMS multimeter; the actual power draw was probably more like 0.66 milliamps. That's less than 1/10th of a watt, which might be so little that it doesn't matter to you, but it is definitely nonzero and does add up over time. My review contains some more details about power draw:
1087785
It plugs into a wall outlet( 2 pronged ) not an ac adapter plug but unfortunately it doesn't run on batteries hope this helps
100396
No batteries are needed. It gets what little power it needs from the USB port
2055089
Comes w/a split cable -- 1 end goes into a USB port, the other end has a plug w/a green end which goes into a green hole in the back of your computer. I think it gets the power from the USB port, but I'm not sure. It's not battery-operated.
808039
No -- It requires an external power source. You can either use a USB cable to connect to a computer or plug it into the wall with the supplied power cord. It can't draw power from your phone/iPad.
647544
None... However, you must USE a separate power supply for the adapter. You must use at least 5 volts @ 2 Amps or 2000 mili-Amps or higher. It is use to power up what ever device that you going to use. Having a USB to power cord which came with the adapter is NOT good enough. My adapter plugs in deep into my laptop. I have problems with some USB devices because of the thickness of the USB end. It gets in the way of the laptop case. I use an extender to help resolve that problem.
1406097
No battery or DC power supply. Comes with AC power supply similar to a laptop. Suspect, that due to its amplification, that any battery supply would not last very long.
443941
The unit comes with a power adapter but you don't need to use it. I have a ext HD, wireless mouse/ keyboard combo controller and my UPS USB cable hooked up to it without the power adapter plugged in.
767799
I have never used it with the battery. I always use the USB plug plugged into my computer.
531095
It can be recharged through the USB port on a computer or you can buy a separate AC wall plug that the USB connector on the battery pack plugs into.