18. Regarding the X1 2nd gen charging

A: 1. Using the X1 2nd gen while charging it will affect it's battery life, so it's suggested to reduce such operations. Since lithium polymer battery charging/discharging is achieved by the chemical reaction of its electrolyte, using and charging at the same time will accelerate the electrolyte chemical reaction, speeding up the dilution of electrolyte, thus affecting the battery life. But it may be perceived within a short period time.

2. When connected to a USB power supply, the power output from the battery will be cut off, so there's no power consumption by this time. But if powered by a 1A/500mA supply, the power will be not enough for the X1 2nd gen's consumption (discharging+charging). In this case the X1 2nd gen will consume power from the battery. 
When the battery is fully charged, the over-charging protection will cut off the charging coercively.

3. If the X1 2nd gen is left unused for a long time, the battery may be over-discharged and cause the battery to age rapidly. Please remember to charge the X1 2nd gen constantly if you don't use it very often.

4.  Using the X1 2nd gen while charging it will make it a bit hotter than usual, which is a  normal phenomenon and there is no need to worry about it.