Due to poor Nvidia driver handling and other issues in Ubuntu, laptop users usually experience a drop in battery life when compared to Windows. Here lie a series of optimisations I used to take my laptop's battery's rate of discharge from 40W while idling to 10-15W on average (managing to get ~8W when reading or really low demanding tasks).
In order to keep track of battery usage and power consumption, powertop will be used. You can note down the discharge rate of the battery, altough this number may be way off sometimes (heard examples of having ~500mW) if not enough data has been obtained.