How to Build a NiMH Battery Pack

An NiMH battery refers to a Nickel Metal Hydride rechargeable battery. These batteries are safer and have a higher density of energy compared to NiCad batteries. Thus, the NiMH batteries have replaced the NiCad batteries in today’s world. Making your own NiMH battery is quite beneficial since it allows you to check voltage of individual cells, is cheaper, and you can make your own configuration as compared to ready-made NiMH battery packs. In order to build your own NiMH battery, follow the simple steps described below.

Tools and Materials Needed

  • Spot welder
  • NiMH battery cells (1.2 Volts each)
  • Heavy 13 gauge wire
  • Heat shrink tubing
  • Blow dryer
  • Voltmeter

Step 1 – Choosing an Appropriate Brand

Before starting with the NiMH battery pack, it is advisable that you choose a trusted brand of batteries. Usually people prefer choosing from Sanyo, Panasonic or Kan. The choice of the brand of the battery totally depends on the one you trust. Use the Internet or skim through your local market to find the best quality cells at the best price. Check for the date of manufacture on the cell as this is sometimes helpful. If the manufacture date of the cells is recent, then the chances of appropriate voltage are high. Once you have bought the cells, move to the next step.

Step 2 – Checking Voltage of Individual Cells

Check the voltage using a voltmeter of individual cells once they have been taken out of the packaging. It should be between 1.1- 1.2 Volts. If any cell is below the volts mentioned, then the cell is not of good standard. It may have fewer volts due to inappropriate or over-long storage. Either go back to the supplier and get it replaced or buy another brand. You will have to change the cell in any case since a single cell with lower voltage can bring the whole battery pack down.

Step 3 – Hooking up the Cells

If you are making a NiMH Battery pack of 12 volts, you will need ten batteries. Hook the positive end of one cell with the negative end of the other. Use a heavy-duty wire to connect them together. Solder it to the negative-positive ends of the cells using a spot welder. While soldering the cells, it is advisable that less heat be applied. This will ensure that the cells work for a longer period of time. This is because the less heat you use the more reliable the cells become. Longer wires should be attached to the cells at the ends of the pack so they may be used to connect to the device requiring the battery pack, whereas shorter wires should be used to connect the cells together.

Step 4 – Using Heat Shrink Tubing

Once the cells have been placed together, use a heat shrink tubing and place the interconnected cells in it. Now, use a blow dryer on the heat shrink. The heat from the blow dryer will cause the heat shrink tubing to shrink and adhere to the cells thus snugging them together. Your NiMH battery pack is now ready for use.