Long down-times, lots of short haul trips: There are many factors that determine when it’s time for a change. You can read the condition of the battery from the acid level indicator (“magic eye”) directly on the battery. Here, black is a good sign: If it's showing light yellow, it's time to visit your workshop. In general, you should have your battery checked on an annual basis. These signs can also indicate defects:
Battery warning indicator is illuminated
Impeded start behaviour
Damages to case
Voltage decreasing under load