Diesel generator sets are the provider of emergency standby power supply after mains failure and power failure. Most of the time, the unit is in standby state. Once the power failure occurs, the unit is required to “start in an emergency and supply power in an emergency”. Otherwise, the standby unit will lose its meaning. How can we achieve this goal? Practice has proved that strengthening daily maintenance is the most economical and effective method, because the unit is in a static state, and various materials of the unit will have complex chemical and physical changes with engine oil, cooling water, diesel oil and air, so as to “stop” the unit. 1. The unit’s starting battery failed. The battery was not maintained for a long time, and the electrolyte water could not be replenished in time after volatilization. The starting battery charger was not configured, and the power of the battery decreased after natural discharge for a long time, or the charger used needed to be manually and regularly switched between uniform charge and floating charge. Due to negligence, the switching operation was not carried out, resulting in the battery power not meeting the requirements, To solve this problem, in addition to configuring a high-quality charger, necessary detection and maintenance are necessary.