About Your Kindle
16 SECTION 2 ─ Kindle Accessories
USB Charging
An additional benefit to plugging Kindle into your computer
or to a powered USB hub is that your Kindle may get a
slow, steady battery charge (trickle charge). Your
computer must be awake for this to occur.
If your computer provides less than 500mA of power over
USB or you are using a non-powered hub, third-party USB
charger, or USB-based auto charger, your Kindle will only
charge if it is in sleep mode or turned completely off.
Helpful Hint: This type of trickle charging may not
occur if your battery is very low. In that case you wil
need to use your power adapter to charge Kindle.