It may appear to be the same and be overlooked. This is where good record keeping will help. Another important of the visual inspection is to make sure there is enough space between each battery. There should be an air gap between each battery. This will allow heat to dissipate.
Some conditions can cause a thermal runaway when the batteries are all tight together.
Each year, all connections must be torqued to maintain the optimal connection. The torque value will most likely be slightly less than the initial torque used when installing the battery. It is important to adhere to the manufacturer's specified torque values to be sure the connection is not too loose or too tight. If it is too loose, the connection could overheat during a discharge and cause problems. Once the connection has been overtorqued, it is permanently damaged.