5V 2A or 12V 1.5A: which charger is faster?

[Farhan_]

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[Levent]

5(v)*2(A)=10W

12(v)*1.5(A)=18W

Which one is higher?

[mariushm]

In theory the 12v 1.5A will charge a battery faster, because it can provide up to 18 watts to your device. The 5v 2A charger can only give 10 watts.

 

However, the device (phone or whatever) must either be capable of working directly with 12v, or must support Quick Charge or USB Power delivery or some other method of signaling the charger to raise the voltage from the default of 5v to 9v or 12v.

By default, the charger will output 5v - the phone or whatever you have normally "talks" to the charger and tells the charger it's safe to raise the voltage from 5v up to 12v.  If your phone does not support Quick Charge or an alternative method, then the fancy charger will only provide 5v at 1.5A , so less than 5v at 2A.

 

Also, it's debatable if it's a good idea to shove so much power into a battery very fast. Yes, you may push 18w into the battery and charge it fast, but the batteries may heat up a lot and at the end of the charging process, the batteries may hold let's say 90% of the maximum capacity. If you charge them slower, at only 10 watts, it will take longer to charge them but the batteries will be cooler and they may charge up to 98-100% of their rated capacity...

 

Charging with just 5v can also be more efficient... for example using 5v to charge a 3.7v..4.2v battery may be done with 97% efficiency ... but converting 12v to 3.7v..4.2v may be only 92-95% efficient ... so if you charge from a power bank or some solar power installation or some source where it's critical to be as efficient as possible, it may make more sense to use the 5v only charger.