Perfect fit: The vacuum is compatible with dewalt 20v max batteries and Mellif 20V batteries. Just plug in your own batteries on our professional vacuum cleaner and start your cleaning! Worry-free from charging: After testing, 3AH battery can maintain the machine for 25-30min use. If you owned more than one battery, you can easily change another fully charged battery rather than the long wait. Furthermore, our machine come with low-voltage protection to protect your battery. The machine will automatically shut down when your battery is about to drain.