Ryobi is a large power tool manufacturer offering consumers affordable, innovative products, according to Ryobi. Ryobi produces a range of new products that operate on single-cell lithium ion batteries, but older models and those requiring greater voltage have 18-volt battery packs. The main problem with 18-volt battery packs is their tendency to gradually lose the ability to retain a charge. Most 18-volt Ryobi batteries are made from 15 nickel cadmium (NiCad) cells, each producing 1.2 volts. If one or more cells go dead, your battery cannot be fully charged, so the time between charges increases until eventually you need to replace the battery. However, a cheaper method is to rebuild your 18-volt Ryobi battery.
Remove the 18-volt battery from your Ryobi tool. Read the label on the battery to check the type of cells it contains. Most are NiCad, but some may be nickel metal hydride (NiMH) cells. It's important to use the correct replacement cells when you rebuild the battery.
Unscrew and remove the cover on the 18-volt Ryobi battery pack with a Phillips screwdriver. If your pack doesn't have screws and is a sealed unit, don't break it open. You need to buy a replacement pack, ensuring you can remove the cover if you need to.
Remove the 15 cells carefully. Some you can pry out using a small screwdriver. If they're soldered in place you need to heat a soldering iron. Once hot, touch the terminal of each cell; as the solder melts, pry out the battery from its compartment. Turn off the soldering iron once you've removed the cells.
Put the 15 cells in a clear plastic bag so they're visible. You need to dispose of them in a battery recycling unit. Don't put them in your regular trash.
Put the 15 replacement cells into the battery pack using the same method as you used to remove the old ones. Press simply into place, or if they need soldering, heat your soldering iron. Place each cell into its compartment and then touch the terminal of a cell using your soldering iron. Introduce the solder and let it melt so it fuses the connection. Remove the soldering iron and solder and let the solder harden. Repeat the process for all the cells. Turn off your soldering iron.
Replace the cover on the battery pack. Screw in the screws using a Phillips screwdriver.
Put your rebuilt battery pack on the charger for an hour. This ensures all the cells are fully charged. Then your 18-volt Ryobi battery is ready to power your tool.