Cordless leaf blowers last different amounts of time based on the power setting you use. Cordless leaf blowers on the fastest setting typically die within 20 minutes but can last well over an hour on lower settings if you have the right model. Customer reviews of cordless leaf blowers will give you a good idea of how much work a model can do on a single charge. One customer reported being able to use the BLACK+DECKER 40V twice in a single charge to clear their courtyard. As in all other things, your mileage may vary.