3. Use a charging USB port or a powered USB hub.
If you don't have a charger handy, you can recharge via a USB port. USB 2.0 ports come in two types: standard and charging. The difference is in the amount of juice they can deliver: A standard USB port delivers a paltry 100mA, whereas a charging port can deliver a much more respectable 500mA. That's why, when you plug a power-hungry device into some ports, it either won't charge at all or will charge very slowly. Though many laptops offer a combination of standard and charging USB ports, many manufacturers do a poor job of identifying which ports are of which type; in such cases, the only way to find out is to try each port in turn. Even more confusingly, some ports on fairly recent laptops can provide up to 1.1 Amps of current when a device that can use it is plugged in. Check with your system's manufacturer to see what types of ports it has and what amperage they can deliver to your device, before relying on them to keep your devices charged and ready to go.
Although USB 3.0 ports can deliver more juice (up to 900mA) than USB 2.0 ports can, they perform at this level only with USB 3.0 devices. If you plug a USB 2.0 device into a USB 3.0 port, the port will deliver the same maximum 500mA that a USB 2.0 port would.
If you use an unpowered USB hub, the available current will be divided across all of the ports, which won't leave enough to charge your devices. A powered USB hub can deliver the full amount of charging juice to each and every port, which makes it a better option for charging your devices.
4. You can use any Micro-USB cable to charge your phone if the phone has a Micro-USB port.
For devices that have Micro-USB ports, you can use any cable that has a Micro-USB plug on the end for charging; you don't need a special cable.
5. The first time you charge a device, let the device charge completely, and then discharge it until it runs out of juice.
The first charge cycle of any device is important: It conditions the battery and helps the device figure out how the battery behaves. So, when you first plug it in, leave the device on to charge for at least 12 hours, then unplug and run the device until the battery is empty.
6. You can safely leave devices charging.
Modern mobile device batteries contain circuits that control the flow of power, so it is safe to leave them plugged in and charging for long periods. When the battery is fully charged, the battery management controller will regulate the flow of power to keep the battery topped up, but won't overcharge it. Which is a good thing, as an overcharged Li-Ion battery could explode.
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