BATTERY PACK CORRECTIVE ACTIONS
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ventilation is included in the system, the ventilation interlock will allow any vehicle to charge. However, if ventilation is not included in the system, the mechanical ventilation interlock will allow vehicles equipped with nongassing batteries to charge, but not vehicles equipped with gassing batteries.
Ventilation Part II, Uniform Building Code, of California Title 24 Code of Regulations addresses location and ventilation issues associated with EV charging. Specifically, these codes address where EV charging equipment can be installed. If a ventilated charging system is to be installed, the codes specify how much mechanical ventilation must be provided to ensure that any hydrogen off-gassed during charging is maintained at a safe level in the charging area. The ventilation rates specified in the building codes are calculated to comply with the NFPA requirements published in Standard NFPA 69, Explosion Prevention Systems. This standard establishes requirements to ensure safety with flammable mixtures. Section 3–3, Design and Operating Requirements, requires that combustible gas concentrations be restricted to 25% of the Lower Flammability Limits. This design criterion provides a safety margin in atmospheres containing hydrogen. Hydrogen is combustible in air at levels as low as 4% by volume of air. Therefore, in order for the charging station to not be classified as hazardous, the hydrogen concentration must not exceed 10,000 ppm, which equates to 1% hydrogen by volume of air.
BATTERY PACK CORRECTIVE ACTIONS Connection Resistance The intercell and terminal connection resistance is set as a baseline during the installation of the traction battery pack. This recording process ensures that an increase in the resistance values can be detected at an early stage, especially those caused by loose connections and corrosion. Normal installation resistance varies greatly as a function of the size of the installation. The variation of the installation resistance is typically from 10 to 100 mW. The installation resistance of a battery or series of batteries can be measured using an ohmmeter or a conductance meter, or a measurement of a voltage drop during capacity testing. It is
