Electronics Parts.
For supplying a safe and convenient battery pack, we choose some electronics components to protect the battery safely and effectively in the working condition.
Connector: This diverse group of components provides an easy and efficient means of connecting the battery pack to the devices. The connectors come in various types, the frequent models are from AMP, KET, MOLEX, JST and so one. |
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Thermistor (NTC): Used primarily with the more sophisticated methods of charging NiMH batteries, this device senses temperature throughout the charging of the battery, which is then analyzed by the charging circuitry. Thermistors are thermally sensitive resistors that exhibit a large, predictable and precise change in electrical resistance when subjected to a corresponding change in temperature. The thermistors typically used in battery packs are negative temperature coefficient (NTC) thermistors. This means that they exhibit a decrease in electrical resistance when subjected to an increase in temperature.
Thermistors come in various types, but the most commonly used and the preferred type is a 10K 1% glass encapsulated with axial leads. Other thermistors used are the epoxy bead type thermistors, but are less desired due to the increased difficulty to assemble into the battery packs.
PTC: The most commonly used component in the assembly of battery packs is the strap-type polymeric positive temperature coefficient (PTC) device. Strap-type polymeric PTC resettable fuses are easily installed in series with the cells inside the battery pack with only a small addition (~1 mm) to the overall dimensions of the battery pack. PTC resettable fuses limit the flow of dangerously high current during fault conditions, which includes accidental, short-circuits of battery.Providing over-current protection as well as over-temperature protection, the polymeric makeup of the PTC resettable fuse latches into a high-resistance state when a fault occurs. While only allowing a small amount of current through the battery, this high-resistance state will remain until the fault is removed. Once the fault and power to the circuit are removed, the PTC resettable fuse will then automatically reset, ready for normal operation. See section
ThermostatThe other commonly used circuit protection device used is the bi-metallic thermostat or circuit breaker. This type of resettable fuse also protects against short-circuit but using an entirely different technology than the PTC resettable fuse. Thermostats use a bi-metal disc that senses both heat and current from the battery pack. When the temperature reaches a predetermined temperature, the disc snaps open the contacts, thus completely breaking the path of the current. When the battery returns to normal operating temperature, the thermostat resets. See section 7.6 for Harding’s standard components.
Thermal FuseThe one-time use thermal fuse is less common. These fuses open at elevated temperatures caused by run-away current. They are a fail-safe measure since the battery will become inoperative once the fuse has opened. These fuses are recommended, if absolute termination of current is needed for safety concerns only.
PCB: applied on Li series battery, including the over-discharge, over-charge and etc. function. It is to protect the Li battery to apply in the safe condition. Suit for the single cell, series pack, and parallel pack.
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