Runtime depends entirely on the UPS model, the age and condition of the batteries, and how much load is connected. A typical APC Smart-UPS 1500VA running at half load provides roughly 20 to 25 minutes of runtime on new batteries. At full load this drops to around 7 to 10 minutes. Smaller models such as the 750VA provide 10 to 15 minutes at half load. Runtime decreases as batteries age. For longer runtimes, external battery modules can be connected to supported Smart-UPS models, extending backup time to several hours at reduced loads. In practice, most deployments pair the UPS with a generator, so the UPS only needs to bridge the gap of 5 to 10 minutes until the generator starts and stabilises.