Power Plan Setting

Go to Control Panel (you'll find it in the Start Menu or otherwise just search for it).

1. Go to "Hardware and Sound"
2. Click on "Power Options"
3. Find the "Power Saver" power plan. 
4. Select the "Power Saver" power plan. 

This will make your computer run slower but your battery life will increase.
If your battery life still hasn't increased, do the following:

1. Complete all of the above steps. 
2. Next to "Power Saver" click on "Change plan settings."
3. Click on "Change advanced power settings."
4. Make sure the "Power Saver" power plan is selected in the drop-down menu. 
5. Double-click "Wireless Adapter Settings" and then double-click "Power Saving Mode;" make sure that the setting is set at "Maximum Power Saving" (if not then change it). 
6. Double-click "PCI Express" and then double-click "Link State Power Management;" make sure "Maximum power savings" is selected; if not, then change it. 
7. Double-click "Processor power management;" then double-click "System Cooling Policy." Make sure it's set as "Passive;" if not, then change it.
8. Under "Processor power management;" click on "Minimum Processor State" and make it 0%. For "Maximum Processor State," select anywhere between 45% - 60% (don't go below 40% because it will likely make your computer too slow and it may freeze). 

P.S. Make sure you only change the settings for "Battery," and, whenever your computer is plugged in, always select the "High Performance" power plan in order to get maximum performance. 
To change to high-performance power plan, click on the little battery icon in the bottom-right-hand corner and click "More Power Options," then find the "High Performance" power plan (it may be under additional power plans, and select it.