The Universal Serial Bus (USB) was introduced in 1996 and has since become one of the most widespread and convenient interfaces for electronic devices. The USB port is a bi-directional data port that provides a supply voltage to power memory sticks, keyboards, mice, wireless interfaces, cameras, MP3 players and chargers.
Most home computers now have USB ports accessible with 5V and 500mA of available current. The USB bus can charge a small single-cell Li-ion pack, but there is a danger of overloading the USB hub when attaching too many devices. Plugging in a charger that draws 500mA along with other devices will exceed the port's current limit, leading to a voltage drop and a possible system failure. To prevent overload, some hosts include current-limiting circuits that shut down the supply when overdrawn. Another method is limiting the current of all attachments to 400mA to reserve 100mA for housekeeping.
Many vehicles now have USB Ports that come standard. Adapters are also available that convert the cigarette lighter in your vehicle to a USB port or even multiple USB ports. With these adapters however, you will need to be certain that it is rated with enough power (mA) to drive your charger device. An adapter rated for 500mA should suffice as a rule but you will want to check the sticker on your charger device.
Summary: You can charge your Electronic Cigarette battery from a USB Port, but there are things to consider. Electronic Cigarette USB chargers will draw between 200-480mA, depending on the particular model. It will be printed on the charging device label. You must consider that the output of the USB may not be able to deliver enough power for the charge.
With that said, another consideration to be aware of is the version of USB device. Now, USB 1.0 has been around for a while (since 1996 as stated above) and it had an output limitation of 100mAh which will not be sufficient to charge your battery. USB 2.0 was released in April 2000 and more than likely any device that you are still using has at least USB 2.0, but it is worth checking before you try to charge your battery. USB 2.0 or higher is definitely what would be needed. On most electronic devices, it will specifically say USB 2.0 or "Hi-Speed" or "SuperSpeed" (for USB 3.0).
And finally, if you are going to use USB to charge your batteries, we highly recommend that you consider an externally powered USB Hub (remember USB 2.0 or higher). A USB Hub will have an external power adapter that plugs into a standard wall outlet. This will not only protect your computer's USB but provide you with much more power available to spread across more than one port.