The solder fume extractor's window will glow red if the battery needs charging. Plug a charging cable into the micro USB and watch as the window glows yellow to indicate the charging process. The window will glow green when the battery is fully charged. A fully depleted battery takes about one hour to recharge. If the extractor is running, then recharging will require more time.
Because the fan only turns on when needed, the solder fume extractor battery will easily last long enough for a typical two or three-hour soldering session -- with the lamp at medium brightness.
Remember, the extractor was designed for either left-handed or right-handed soldering. Just flip the enclosure end-for-end to point the motion detector to the other side.
The extractor will work best if it's kept close to the soldering action. Experiment with distance to maximize the absorption of those pesky fumes. Happy soldering!