All USB cords carry the same 5V, regardless of if it's got a 30-pin head or a microUSB plug, whether it's first-party or third. That means DC chargers are now brand agnostic; if the volts, amps, and connectors are compatible, an Apple wall wart can charge an HTC just as easily as a Samsung.
All USB ports are 5 volts DC. The transformer (or computer) will take care of converting the 120/220 AC current to the necessary 5 volts DC.
Your cell phone, camera battery charger, and e-reader are not dual voltage, you plug a USB cable into them, and USB is always 5 volts DC. The thing you plug into the wall is not "part of the charger", it is the complete charger. It converts the electricity coming out of the wall into 5V DC which is what your phone etc.
But a USB memory stick (which I assume you mean by “a USB”) has no power inside it and is certainly not capable of electrocuting you. Even a properly working USB cable cannot harm you: it delivers only 900mA at 5V, (or 2.1A for some non-standard chargers).
In the USB 1.0 and 2.0 specs, a standard downstream port is capable of delivering up to 500mA (0.5A); with USB 3.0, it moves up to 900mA (0.9A). It's universal; you can put it in either way and it will work, unlike with USB, and like Apple's Lightning connector.
The standard USB port, be it USB 1.1 or USB 2.0, delivers 5 volts of electricity and allows your connected device to draw 500 milliampere. As this is standardized among USB devices, any device that can charged via USB is safe to plug in to your computer.
USB charger - Computer Definition
A power adapter that generates the 5 volt DC standard required by USB. The charger plugs into an AC outlet, and a USB cable plugs into the charger. The devices sense when they are connected to a computer versus the charger and regulate their current draw. See power adapter.Quick Charge automatically adjusts the voltage supplied according to all of the applicable conditions. If the port is listed as being 2.1A then it is not Quick Charge. If your device does not support Quick Charge, then it won't Quick Charge regardless of what cable or adapter you use.
Yes, USB 3.0 is generally backward compatible with USB 2.0. Yes, you will only get USB 2.0 speeds if you plug a USB 2.0 device into a USB 3.0 port. However, there are some USB 2.0 devices, such as keyboards and mice, that do not work well with USB 3.0.
In the Device Manager, expand Disk Drives to find your USB device. Right click on the device and select Properties. In the Properties window, select the 2nd tab called Policies and you will see two options. Most likely if you are experiencing slow speeds, it is set to the default Quick removal.
USB-C, USB 3.1, and Transfer Rates
That's double the bandwidth—as fast as a first-generation Thunderbolt connector. USB Type-C isn't the same thing as USB 3.1, though. USB Type-C is just a connector shape, and the underlying technology could just be USB 2 or USB 3.0.What is the difference between USB 2.0 and USB 3.0? First the transfer rates: USB 2.0 offers transfer rates of 480 Mbps and USB 3.0 offers transfer rates of 4.8 Gbps - that's 10 times faster. Note that the transfer speeds also depend on the device in use in addition to the bus type and USB ports and cables.
The USB 3.0 specification was published on 12 November 2008. Its main goals were to increase the data transfer rate (up to 5 Gbit/s), decrease power consumption, increase power output, and be backward compatible with USB 2.0. USB 3.0 includes a new, higher speed bus called SuperSpeed in parallel with the USB 2.0 bus.
Right-click on the "USB Root Hub" you want to change, and then click on "Properties" to open the USB port's Properties dialog box. Under the Power Management tab, you will see the option for restricting power to the USB port to save battery power.
Advantages of Using a Powered USB Hub to Charge Your Devices
Since powered USB hubs used to charge multiple devices get their power from AC adapters that are plugged into electrical outlets, they won't need to take any power from your computer. This means faster charging and less strain on your computer's system.if you overload, the device (or one of the devices) will just not work as the USB port will limit the power output.
Yes, they're the same as regular USB wall warts just built into the wall outlet. It could be lots or little or even none depending on how well they're designed. I imagine if enough of these things get installed there will be calls for regulations requiring switches or a very small idle power.
Static electricity causes ports in the hub to stop working. Put the power plug back into the hub. Then put the USB connection plug back into the hub and everything will work again until static electricity somehow builds up and incapacitates the ports again.
Unpowered. Non-powered, or passive, USB hubs do not have an external power source and only pull power from the computer's USB port. The USB 3.0 standard improves power management capabilities over the previous versions and may be able to use higher power devices that hubs running older standards can't.
