What is necessary regarding the bus batteries?

The necessity for bus batteries to be securely mounted with no damage ensures that they remain stable during operation, reducing the risk of short circuits and accidental disconnections. Proper mounting also prevents vibrations from causing wear and tear that can lead to battery faults or failures. Having a secure battery system is crucial for maintaining the safety and reliability of the bus, as well as ensuring that electrical systems function correctly without interruption.

Other options may have their own importance in different contexts. For instance, while disconnecting batteries can be a safety measure during maintenance, it is not a requirement for regular operation or inspection. Charging batteries regularly is certainly good practice and may be necessary in specific cases, but it is not a universal requirement. Covering battery cables could help protect them from environmental damage and accidental contact; however, it is not universally mandatory as part of the pre-trip inspection process.