Something doesn't quite add up there, either the asus supply is providing more than 2a (10W) or your battery isn't getting fully charged (calibration is off)
The Z1 has a 3Ah (3.8V) battery, which is at least 11.4Wh.
With 100% efficiency (no heat generated during charging and device off) you would only be able to charge the battery 87.77% in 1 hour.
It is possible at the kernal level to specify max charging current so a custom kernal may have a lower charging rate to preserve the battery, if the rom uses a stock kernal then something might be draining the battery whilst on charge (google / data sync etc)
Let me check that one more time.
I'll charge it tomorrow again and will check exact time.
What I wrote isn't 100% correct, it's around 60min.
But you are right - that is strange.
I never thought about that, it could be more minutes or really, it doesn't charge to 100%.
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