DEWALT DCF815S2 12V Review
Pros: Great integrated worklight, decently convenient
Cons: Poor measured battery life, lackluster speed and torque showing in our tests
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Our Analysis and Test Results
This impact does have a good built-in worklight and a quick insert chuck but these factors are far outweighed by its lengthy list of flaws in our opinion.
Regrettably, the list of things we liked about this impact driver is fairly short. As mentioned above, we were impressed with the amount of light this tool provides. It does a great job of fully illuminating your work area but it unfortunately doesn't stay on unless you are holding the trigger. However, you can press the trigger just enough to turn on the light without the chuck starting to spin.
This impact also lets you insert a ¼" hex bit into the chuck just by pressing — you don't need to lift the locking collar like other models. The DCF815 is also on the lighter side for these products. In terms of things we liked, that's pretty much it — we warned you the list is short.
The DCF815S2 got off to a rough start by delivering one of the worst performances we have seen to date in our most important rating metric: speed. It is was one of the slowest we have seen at driving in screws, taking significantly longer to sink ledger and lag bolts into sheet goods or dimensional lumber. It took almost four times as long on average to drive a ledger screw into a stack of plywood or 2x12s as the fastest model and almost couldn't even seat the head of a lag bolt against the wood.
This pint-sized impact didn't pack much of a punch in our torque tests, falling flat compared to the rest of the group. It only managed to tighten a ¾" nut to an average of 110 foot-pounds during our tightening test — far less than the 300 foot-pounds or so the top tools could achieve.
The DCF815S2 can comfortably break a ¾" nut loose when it was tightened to 75 foot-pounds and only took 5 seconds to crack one tightened to 100 foot-pounds loose but failed to free anything tighter than that.
For our battery assessment, we alternated between setting 14 3" ledger screws and driving in 3 ½" lag bolt in and out, scoring each tool on the number of cycles completed. Most tools completed at least two or three cycles of this but the DCF815S2 couldn't even make it through a single cycle on a full charge, dying before it could remove the lag bolt. This impact is also one of the louder models, averaging close to 100 dBa while driving a screw at the ear level of the operator in our tests — much louder than other models. This is definitely loud enough that it can exceed typical safe noise exposure levels with continued use and you should always follow the manufacturer's instructions regarding personal protective equipment when using this tool.
Overall, this tool is far from a good bargain buy, costing much more than other products that received much higher scores.
It was a struggle to find positives with this product and the few we found were far overshadowed by its long list of negatives in our opinion. We would be very reticent to suggest the DCF815S2 for your next impact driver purchase and would strongly suggest you consider other options.
— David Wise and Austin Palmer