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


No. You simply cannot use a lower voltage charger in a reliable manner. The battery needs to be charged at a higher voltage than the battery holds.

Too high voltage and the battery can be damaged. Too low voltage and the battery isn't getting charged. Most chargers should prevent damage in such a case, but it's possible to break your charger with this.

You're not required to use the original charger, but make sure you get at least the voltage right. If the original is 9V, don't use anything different than 9V unless you know what you're doing. If the original is 12V, use 12V. Too many Ampere is irrelevant, not enough would result in a very slow charging process.

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