The new DEWALT 20-Volt Stud And Joist drills come in the Power Detect model and FLEXVOLT Advantage model. DEWALT claims the Power Detect models will look at the battery that is attached to the tool and increase the power accordingly. The Flexvolt Advantage tools will increase the power when a Flexvolt battery is used. In our testing, we wanted to prove and show what battery was the best for each line. Would the Power Detect model work best with a Flexvolt battery? Would the Flexvolt Advantage work well with a larger XR battery?

To do this we used the voltage sag of each tool to determine the best battery along with the speed of the hole being drilled. We never expected to find that there is a certain level of battery that seems to switch on the power. We found the power to be switched on with both tools at the 8Ah level. That was proven with the larger voltage sag with the 8Ah over the 6Ah and the speed of drilling increasing with the 8Ah level.

It is very clear that the lightest battery and best performing on each tool was the XR 8Ah battery, but both performed well, very well in fact, with the 9Ah Flexvolt battery.

We used the 5Ah, 6Ah, 8Ah and 9Ah Flexvolt in this video because the 9Ah Flexvolt and 8 Ah 20-volt were talked about on the box of the tools. The 6Ah was a guess that performance would increase enough to justify the purchase. That theory failed. We did not use the 6Ah Flexvolt or 12Ah Flexvolt because it would have increased the video time and the level of performance would be on par with the 9Ah Flexvolt. The only change would be runtime with those batteries.