DIY: Upgrade BOSCH Drill to Lithium-ion Batteries

If your cordless drill has been used for a while and the original battery isn't performing well anymore — it drains quickly after being fully charged — you might consider upgrading to lithium batteries. Cordless drills require high-performance batteries, specifically those with a high instantaneous discharge rate, to support quick starts.

The 18650 batteries, arranged in a 3-series 2-parallel configuration with a suitable holder, fit perfectly. Each battery has a capacity of 5200mAh and is paired with a 20A protection board, as shown in the image below.

Before installation, the batteries were tested, including fitting them into the drill and checking charging performance.

The image below shows them installed and sealed.

The final setup features a 5.5mm DC connector and uses a 12.6V lithium battery charger with excellent results. The bulky original charger is no longer necessary. This battery setup comes standard with two cells; the previous configuration had three series lithium batteries totaling 2600mAh, which performed well with extended usage times when fully charged. This new setup undoubtedly offers better performance, noticeably more powerful due to different core materials.

Overall photo