DIY Modify Cordless Drill with 18650 Battery

If you're interested in modifying a cordless drill, take a look at this article.

A cordless drill is a very handy power tool, useful for drilling holes, screwing in screws, and more. However, after a few years of use, the battery will gradually degrade. It won't be able to drill many holes before it runs out of power, and it charges quickly but still doesn’t last long. At this point, you have two options: buy a new battery or replace it with new 18650 cells. Alternatively, if you have 8 power cells and a high-power protection board, you can repurpose the cells from an old drone. In that case, follow this guide to assemble your own new power battery.

Here's what the finished product looks like:

Each battery pack has an energy capacity of 66.6Wh and is made up of four 3.7V, 4.5Ah cells with low internal resistance, connected in series. It can support a continuous discharge of 20A, with a peak current exceeding 50A.

The casing can be 3D printed and consists of five parts: the upper tube, middle connector, bottom casing, and two clips.

To make charging more convenient without needing a dedicated charger, a constant voltage and current module is placed inside the upper tube. This allows the battery pack to be charged by any power source ranging from 18V to 35V, with a power output of 40W or more. When charging, the indicator light is orange, and once fully charged, it turns green.

That's it!