Battery power has decreased significantly

The Liliput is as the name suggests beautifully small and lightweight.
Unfortunately, the battery power after just a few months after strong. The vacuum cleaner will depend forever on the charger until it is fully charged and then times it sucks for a maximum of 1-2 minutes with adequate strength. It is enough sometimes barely around the table and suck the chairs after breakfast. Charging time and suction there are out of proportion. Because the really cheap price itself is still too expensive. I am very disappointed!