How To Use An 18V Ryobi Battery With 12V DeWalt or Hercules Cordless Power Tool

I've needed a cordless extended reach ratchet / socket wrench to save time when working in hard to reach places. The Milwaukee one with the low profile sockets is sweet, but I can't justify the cost for occasional use. If I was using it daily for my work, then it could be worth the investment.

Dare I say it [Harbor Freight] actually has a good 12V Cordless 3/8 in. Extended Reach Ratchet sold under the Hercules house brand. They also have a 1/4in version. The watcher looks nice, is inexpensive at $50, and YT reviews show that it performs per it's specs. However it does not come with a battery. Not wanting to invest in the Hercules brand battery eco system, I had to find a better solution.

Hercules 12V batteries and DeWalt 12V batteries fit on each other's tools. However, the temperature sensor contacts are not in the correct positions, so the Hercules tool won't work when plugged into a DeWalt 12V battery. The easiest solution is to disconnect the temp sensor wire inside the Hercules tool and add a resistor to trick the tool into thinking it's connected to the battery temp sensor.