How to Rebuild Batteries for Cordless Tools

Modern cordless power tools have the same functions as wired power tools, and they have the added benefit of total mobility. You can use them practically anywhere because they don't require an electrical socket. They are also safer because they operate on low voltage supplied by a rechargeable battery. The one issue with cordless power tools is that battery packs have a limit to the number of times they can be recharged. That number varies with usage, but if your cordless power tool operates for increasingly shorter periods between charges, its battery pack needs to be rebuilt.

• 1

  Remove the battery pack from your cordless tool. Usually this requires flipping open a protective cover or removing one screw, then sliding out the battery pack.

• 2

  Remove the battery pack cover. Use a small screwdriver to remove the screws. If the cover has spring clips, insert a small flat-head screwdriver under each clip fastener to pry it off. The battery cells that form your cordless tool's battery pack should be visible when the cover is removed.

• 3

  Remove each battery cell from the battery pack. Each battery is either clipped or soldered in place. If the battery cells are clipped in place, pry out each cell using a small screwdriver. If they are soldered, heat a soldering iron that has a small tip suitable for electrical repairs. Place the soldering iron's tip on one battery terminal and allow the solder to melt. Remove the soldering iron and carefully lift that battery cell out of its compartment. Do this quickly, before the solder hardens. Turn off the soldering iron when you are finished removing all of the battery cells.

• 4

  Read a battery cell label to determine its type -- nickel cadmium (NiCad), nickel metal hydride (NiMH), lithium polymer (LiPo) or lithium ion (Li-on).

  If the type is Li-on, dispose of the pack by taking it to a recycling center and purchase a replacement pack. Don't attempt to rebuild it because specialist knowledge is required. Li-on battery packs have power surge breakers to stop overcharging.

• 5

  Purchase the correct type and number of replacement batteries if your cells are NiCad, NiMH or LiPo.

• 6

  Put the new battery cells into the battery pack, using the same method that secured the original batteries in the pack: Push them in place or use a soldering iron to secure them. Ensure the battery terminals face the correct way. Each compartment is labeled positive and negative.

• 7

  Dispose of the old batteries. LiPo batteries are environmentally friendly; wrap them in newspaper and place them in your regular trash. NiCad and NiMH batteries are not environmentally friendly and must be taken to a recycling center for safe disposal.

• 8

  Install the cover on the battery pack. Screw the screws in place or push the clips into place.

• 9

  Place the battery pack into your cordless tool. Secure it by refastening the protective cover.

• 10

  Put your battery on charge for one hour to ensure all the battery cells have a full charge.