Originally Posted by felonwan
I always wondering that why the authentic charger can only charge the battery. Why they do not provide an AC Adapter like that for laptop which is capable to run the device without the battery?
Other chargers can also charge the battery.
The kindles may have a 3G modem, and its peak load may exceed what the charger can provide through a microUSB port. In fact, on some devices such as an iPad, it is reported that the battery still drains if you use it at full brightness while it is attached to its charger.
If the kindle checks for an approved charger by some kind of communications with a chip in the charger, it could be for deciding what charging method to use (fast or slow). I have not seen that in the GPL source code though.
But I have seen code that checks for a special file (similar to ENABLE_DIAGS) on the USB drive to allow booting without an approved battery (with code comments that it is for hardware testing purposes), so it may be possible to run on a charger without a battery if you set this flag. That way you could still use a kindle (tethered to a charger or external battery), even if its own battery is toast (as seems to be the case in multiple K3 posts in the parent forum).