The PTC component provides protection against excessive current in the battery pack. As the temperature rises, the resistance of this component increases linearly. When the current or temperature reaches a certain threshold, the resistance value undergoes a sudden change (increases), causing the current to drop to the mA level. Once the temperature drops, it returns to normal. This component can be used as a connection piece for batteries and connected in series to the battery pack.
In lithium-ion battery electronic circuits, PTC is commonly referred to as an overcurrent protector and its cost is relatively high.
PTC, also known as a current-limiting protector, is mainly used for short-circuit and overload protection in low-power electronic devices.
II. Thermistor Switch NTC:
This NTC component can quickly sense changes in current and temperature in the circuit. If the temperature is too high or the current exceeds the limit, the temperature of the bimetallic strip inside the switch will reach the rated value of the switch. The metal strip will then jump out, serving the purpose of protecting the battery and the electrical appliance. This is often seen in the application of circuit protection for lithium-ion batteries.
If the NTC metal sheet of the thermal switch detaches, it may fail to reset, resulting in the inability of the battery pack voltage to function.
III. Fuse FUSE:
When the current in the circuit exceeds the rated value or the temperature of the battery rises to a certain level, the FUSE fuse melts, cutting off the circuit to protect the battery pack and the electrical appliances from damage.
FUSE can sense the current and temperature of the circuit. Once the fuse melts, it cannot be restored and needs to be replaced in time. This process is rather troublesome. However, there are now self-recoverable FUSE fuses available on the market.
Under the conditions of an environmental temperature of 20℃ and when the self-resetting fuse has reached thermal equilibrium, 100% of the current flows through the self-resetting fuse. When the environmental temperature exceeds 20℃, the current passing through the self-resetting fuse will be reduced. When the environmental temperature reaches 85℃, the current passing through it is only half of that at 20℃. When the current flowing through exceeds twice the rated current, the self-resetting fuse will act.
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