Guide to Upgrade Old NiCd Power Tool Batteries to Lithium-ion

Step 1: Check the Old Battery Voltage and the Polarity

Check the old battery voltage and the polarity (18 volt DC for Black and Decker cordless drill)

Step 2: Choose the Right BMS

Choose the Right BMS for Your Power Tool Battery (here 18volt - 5S Lithium Cells in a Row )

Step 3: Open the Old Battery Case

Open the old battery case

Step 4: Inside the Old Battery

The case and the old NiCd cells. The old batteries have 3 connectors, we need only the two (positive, negative). The third one it's for the old NiCd charger that we shall not use.Track the connections from the batteries to the main negative and main positive connectors

Step 5: Check If the New Batteries and the BMS Fit Inside the Old Case

Check if the new batteries and the BMS fit inside the old case. Use lithium ion batteries with

high amperage output (min 20A). Do not use laptop batteries because they had low amperage output (0.5A)

Step 6: Charge the New Lithium Ion Batteries

Check the voltage of the new batteries. All batteries must have same voltage. I had used the LG HG2 INR 18650 3000mAh cells (brown color). (in the photos are the Sony Konion VTC6 for another project)

Step 7: Use Adhesive Paper Insulator Gasket

Use adhesive paper insulator gasket at the positive and negative side of the batteries

Step 8: Insulate Properly the Lithium Cells

Use Kapton tape at the ends of the batteries (Polyimide)

Step 9: Use Heat Shrink Plastic

Use heat shrink plastic to form the battery packs

Step 10: Spot Weld Tips

Cut the nickel plates and apply a small amount of solder at the middle for the cables of BMS. Use low energy at the spot welder and test it first.(Kweld spot welder).Warning! Do not use huge amount of energy because you can punch a hole at the batteries and then you must throw it to the battery recycling bin

Step 11: During Spot Welding

The battery pack after spot welding the joints. Mark the numbers of each terminal and the number of the joints

Step 12: Prepare the BMS

Weld the balance cables to the BMS before the connection to the battery pack to avoid short circuits.I had use 2 different types of BMS. Use Kapton tape under the BMS for better insulation and protection

Step 13: Prepare the Load Connectors, the Charging Port and the Voltage Tester

Check the old battery connectors. Install the plug for the new charger input (Port 5.5 x 2.5mm). Install the battery tester (21V for the 5S battery)

Step 14: Solder the Cables of BMS at the Joints

Test the balance cables for the BMS. Solder the cables at the joints with the specific sequence that it gave us the manufacturer of the BMS (first the main Negative of the battery to the B-, then B1, B2, B3…etc.)

Step 15: Secure the Battery Pack and the BMS

Use double sided tape to secure the BMS to the battery pack. Soldering the cables of the charger port, the cables of the main output and the cables of the tester. The voltage tester have two cables one red (positive) and one black (negative). Solder the red cable to the main positive of the battery pack, and the black to the main negative. Use double sided tape to secure the battery pack to the case

Step 16: Lithium Battery Charger

Use the lithium ion battery charger to for the specific voltage 21V for 5S battery pack (Warning we need lithium battery charger NOT power supply).Charge the battery with the new cells (red LED at the charger)