Unicorn Original Circuit Board
The Unicorn with dual 18650 batteries did not make it to 15 hours of use. The batteries are connected in parallel and should have lasted at least a full 24 hours – and should last even longer than that, depending on the mAh of the batteries.
As it turned out, the electronics by Unicorn are just horrible. They claim it is a Yihi chipset – and it is not. I found several problems with the Unicorn chipset. First, it continues to fire even after releasing the fire button. It's firing, but not at full power, the power seems to taper off over about a six second time frame. But that extra time of putting out power to the coil means that the batteries will get used up much faster and will waste your coil. The second problem is that charging the batteries through the micro USB port on the bottom of the unit took nearly 14 hours of dedicated charging time (no pass through use while charging).
I have now replaced the circuit board with a true Yihi SX 330 and I am getting 30 hours of heavy use vaping from it before needing a recharge. And charge time with the real Yihi SX 330 is about 4.5 hours.
Here are two pictures of the Unicorn chipset ... definitely not Yihi.