Have a overall inspection on your dell battery before buying a new battery

DELL Inspiron 15 7537 14.8V 3950mAh laptop battery

Please follow the steps below to calibrate the laptop battery and to make sure whether to buy a new one. 

First: Charging the battery 
Fully charge the battery when the laptop is in use. 
To charge the battery: 
1. Insert the battery into the laptop. 
2. Connect your notebook to external power through an AC adapter. (The battery light comes on) 
The laptop battery light turns off when the battery is fully charged. 
Discharging the battery disable hibernation fully discharge the battery to temporarily disable hibernation. 
To disable hibernation: * Select the Power Meter icon in the taskbar, or access to Power Options> Hibernate and uncheck Enable hibernate support check. 

Second: The battery discharge 
After the battery light turns off, indicating that the battery pack is fully charged, start the performance of the laptop battery. 

Third: The battery recharge 
1. Connect your notebook to external power and keep the laptop connected until the battery is fully charged and the light goes out. You can use the laptop while the battery is charging, but the laptop battery pack charges faster if the PC is off. 
2. Select the Power Meter icon in the toolbar or select Start> Control Panel> Performance and Maintenance> Power Options Power Schemes. 
3. Rewrite the 3 position which he wrote for the 3 options in the coat, in the column and the 3 options in the column that runs on batteries. 
4. Select the OK button.