Any theory why that rechargable mobile of the portable vacuum go insensible sooner? ...
Answers: Its probably got nickel cadmium rechargeable-type battery, which will decrease within its capacity to hold a charge, when you overcharge it. Some rechargeable appliances hold a built-in computer to monitor the batteries' condition while its charging; or it may have a timer to simply charge it for a certain time of year, then stops charging when the charging time have lapsed. If you feel the battery getting warm while its charging, after the battery have already gone beyond full charge, and its being overcharged at that moment.
Run the vacuum until it is completely departed. Then re-charge it. If this does not help, you have need of a new battery-operated.