That depends on which model we are talking about. The Predator 2000 inverter generator should run up to 6 hours at 50% load. As for the larger open frame Predator generators such as the Predator 8750 or 6500, the manufacturer claims these can run for 12 hours at half load. Some reviews left by the users indicate that this time is usually a bit shorter. 10 hours is probably the safest bet.