Velleman DVM850BL Digital Multimeter "scales changing batteries" Questions

how to use Voltage testers and volt meters are two different things.  A meter will provide a an indication of the exact voltage and type AC or DC.  A tester on the other hand simply provides

I purchased the velleman DVM850BL to check current drain from my vehicles batteries as I keep having to recharge my batteries pretty often. Since I am not an electrician or electronic tech, I would ...