Lithium-Ion batteries though have high energy density and light in weight, are very dangerous if abused i.e., if you overcharge or undercharge the battery or draw more current than it can provide then it can explode damaging the surrounding or even potentially harm the humans around. To prevent this to happen you should use your batteries with a protection board. This 3S Lithium-ion Battery Protection Board monitor protects three cells connected in series by monitoring the voltage and current in and out of the battery pack and if any unsafe condition happens then it will cut off the battery from the load or the charger. This can be used in any DIY project where the current does not exceed 20A like Arduino or Raspberry Pi based projects, 3D printers, Quadcopters, Robotics applications etc. This Board is suitable for 18650 cell having nominal voltage of 3.6V or 3.7V.
 
Specifications
Short circuit protection
Overcharge protection
Over-discharge protection
Overcurrent protection
Overcharge Voltage: 4.2V
Maximum Working Current: 20A