I have 2 V7 slim stick cleaners. One works as expected while the other shows the characteristics as indicated in my title. On normal mode it works fine but after switching to max power setting it cuts out after 2 seconds. At this point the sweeper is dead and will not work in either mode. I have to connect the charger for perhaps 5 seconds to get it to work in normal mode.  I swapped the batteries between the 2 machines and the fault followed the battery. I think that the battery does not get emptied by going  to max power but something in the controlling circuitry calls a halt and the unit shuts down. I see no physical damage to the battery, contacts are clean. The fact that I plug the charger in for just a few seconds and the unit works on normal power makes me thing the circuit fault is reset by this action. I conclude that if I needed this sweeper to run on max power I need a new battery.