I ordered the new Zenfone 2 and it only comes with the "Boostmaster" quick charger that outputs 9v and 2A. Also, I saw pictures where the visible part of the battery in the phone says "+9v 2A" on it.
I want to know is it safe to use a regular 5v USB charger to charge this phone if I do not want to use the quick charger?
I am not sure since I read through these threads:
https://electronics.stackexchange.com/questions/29259/charging-devices-voltage-and-amperage
https://superuser.com/questions/172257/can-i-use-a-power-adapter-with-more-current-but-lower-voltage-on-another-laptop
and I am concerned about these quotes:
Too low voltage may do damage. Slightly too low may work AOK or at reduced current. Too low may damage equipment but not usually. Too low may damage charger but not usually.
If the voltage is too low, you'll get either nothing, or odd / failure behavior when the power draw on the system gets high.
I'd be more worried about the undervoltage. It may put a strain on the voltage regulator in your laptop and may also put a strain on your battery