Let me tell you, these Fhybat batteries saved my weekend DIY project when my original Dewalt ones decided to quit mid-job. The 3600mAh capacity means I can drill through an entire deck's worth of screws without that annoying 'low power' blink.
What surprised me most was how they handle my old DC935 drill - the power delivery feels just like OEM batteries, no weird surges or sudden drops. I accidentally left one charging overnight (oops), but the protection circuits did their job - no swelling, no weird smells.
The real test came when I used them in below-freezing temps in my unheated garage. While they did drain a bit faster than in warm weather (expected with any battery), they kept my impact driver running through assembling 3 sets of shelves.
After 4 months of alternating between these two batteries for various tools, they still hold about 85% of their original charge time. For the price of what one official Dewalt battery costs, getting two reliable performers? That's what I call a power tool win.