Battery 101


5s 18V-21V 15A Li-Ion Rounded edge Protection board

5s 18V-21V 15A Li-Ion Rounded edge protection board is a small PCB mounted Lithium Battery protection module. This small and smart protection module comes with various features like Short-circuits, Over-charge, Over-discharge and Over-current protection. It is straight forward to install and convenient to use in all your DIY portable projects.

Suitable for lithium-ion cells in a 21V (max voltage) 5s configuration.


  • Model: 5S Li-ion – 18V-21V
  • Over-Charge protection: 4.28±0.05V
  • Over-Discharge protection: 2.55±0.08V
  • Continuous discharge current: 15A
  • Max peak discharge current: 25A
  • Static current: less than 20uA
  • Internal Resistance: Less than 50mΩ
  • Operating Temperature: -20℃ -60℃
  • Delay self-recovery
  • Size: Approx.: 89 x 18 x 4mm

Package included: 1 x Li-ion Battery 5S 15A Protection board.



These BMS protection modules may arrive "Activated". Apply 18V-21V across the charge/load terminals will reset the board.  If after assembling your pack, you have zero volts at the PCB terminals or if you've shorted the PCB terminals, connect 18V-21V to the charge/load terminal will reset the board.



This BMS will require a competent and knowledgeable person with an electronic background and skills to install and operate. As these are sensitive products, we will only accept returns if its un-opened and un-used. 

Please double check and triple check your wiring, especially the balance/sense wires are correct. Even temporary incorrect wiring may damage this device.



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