How to Repair Battery Packs

Whether you're a DI, or an RC enthusiast, you'll probably need to repair your battery pack eventually.

Battery packs are an essential part of DIY jobs as they power your cordless tools. Additionally, battery packs are increasingly relied on by remote control (RC) enthusiasts to power their RC models because today's lightweight lithium-based battery cells produce high voltage and have greater endurance. However, battery packs can go wrong and buying a replacement can be an expensive option. If your battery pack has stopped working properly, try repairing it yourself; you have nothing to lose except an hour or so.

Things You'll Need

• Screwdriver
• Replacement battery cells

Instructions

1. Remove the cover from the battery pack. It has several screws holding it in place so use a suitably-sized screwdriver and undo the screws. Lift the cover from the battery pack once the screws are removed. You will see multiple cells inside the battery compartment.

2. Remove the complete cell unit from the battery compartment so you can access the cells. Simply lift it up from the compartment and place it to one side.

3. Test the voltage from each cell using a multimeter. Set the multimeter to measure volts. The cells clearly state the output voltage and type. For example, nickel-based cells produce 1.2 volts while lithium-based cells produce 3.6 volts.

4. Place the sensor on the end of the red wire attached to the multimeter onto the positive terminal of the first cell in the battery pack; it's marked "+." Place the sensor on the end of the black wire from the multimeter onto the negative terminal of the same cell; it's marked "-."

5. Read the meter display. It reads 1.2 volts, if the battery pack contains nickel-based cells, or 3.6 volts if the pack contains lithium-based cells. If the measurement is 5 percent off either way, the cell is fine. However, cells that have a voltage below 5 percent of the label on the cell need replacing.

6. Check every cell using the same method. Cells producing a voltage below 5 percent of the labeled output need to be marked using a pen, as they need replacing.

7. Remove any cells you marked using your pen from the battery pack. Pry the cells out from the battery holder using a small screwdriver.

8. Purchase replacement cells from an electrical or hobby store. Take a bad cell along so you get exact replacements.

9. Put the new replacement cells into the battery pack. Insert the battery cell container into the battery pack compartment. Replace the cover and tighten the screws using a screwdriver.

10. Put your battery pack on charge so all the cells have the same charge. Remove from the charger and use your repaired battery pack in your device as usual.

References

• Buchman: Batteries in a Portable World
• Electropaedia: Nickel Cadmium Batteries
• Battery University: Charging lithium-ion batteries
• RCHelicptorfun.com: Understanding RC LiPo Batteries
• Battery University: The Li-Polymer Battery