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Protective Circuits

Cell protections

Lithium-ion cells have built-in safety devices such as PTC (Positive Thermal Coefficient, which creates high resistance during high current surges) and CID (Current Interrupted Device, which opens the circuit when pressure exceeds 10 bar) for cylindrical cells. Pouch cells include a protective circuitry board that handles UVLO (under-voltage lockout) and OVP (over-voltage protection).

Block protections, BMS

At the module level, a BMS (battery management system) is added to manage communication with other components. This circuit secures input and output current, monitors instantaneous voltage, and checks temperature. The BMS also manages cell balancing, calculates SOC, and prevents charging below 0°C.

Precautions for use

Lithium-ion batteries shall not :

  1. Be charged below 0°C : this permanently damages the anode.
  2. Be discharged below the discharge Cut-off voltage (approx. 2.5V) : this damages the cell.
  3. Be charged above the charge cut-off voltage (approx 4.2V), for security reasons.