Charging Tytn II via Advanced W-ZERO 3 es

Today, I had this idea that popped into my head. Since Advanced W-ZERO 3 es has a USB host capability, why not charge the Tytn II by this?

I just connected a miniUSB cable from my Tytn II to the Host cable that is connected to the Advanced W-ZERO 3 es. Surprisingly, it worked even when the screen was on ! This will be a temporary solution to drain Advanced W-ZERO 3 es' battery to charge HTC Tytn II. I am sure the same process will work on other smartphones as well.