How long do cordless vacuum batteries actually last per charge?

Advertised runtimes (50–70 minutes) almost always refer to eco mode with a non-powered tool. Real-world reports are far shorter on max settings: r/dyson owners report roughly 20–23 minutes in auto and as little as 6 minutes in turbo on the V15, and budget-vacuum owners frequently mention not finishing more than a couple of rooms before recharging.