A typical cordless cleaner can run for between 40 to 60 minutes on a fully charged battery. Of the best cordless vacuums in this guide, the Numatic Henry Quick at #6 and Dyson Gen5detect at #9 jointly lead the field with maximum runtimes of 70 minutes – but like all cordless cleaners, that's based on using them in their default power modes, not their maximum power modes. You'll typically find that if you run your cordless at max power you'll get around a quarter of the battery life. Many more advanced models will show you how much cleaning time you have left based on your current settings.
If you think you'll be running your cleaner on max power all the time, it might be wise to look for a model with swappable batteries. That way when you run out of power you can pop in a second battery and pick up picking up from where you left off.