Makita batteries that produce 9.6 volts contain eight nickel cadmium (NiCad) or nickel metal hydride (NiMH) cells, each producing 1.2 volts. Both types of cell are reasonably reliable, but it is important for you to occasionally fully discharge your battery to keep it in good condition. Nickel-based cells suffer from what is referred to as the memory effect, which is more prevalent in NiCad cells. The memory effect occurs because your battery keeps getting charged, when it's only partially discharged. The cell crystals expand and the Makita battery, or any other nickel battery, is unable to retain a full charge. Fortunately, revival is a simple procedure.
Use your Makita 9.6 volt battery in your power tool until it stops operating. Remove the battery and put it in the charger and then turn on the charger.
Let the Makita 9.6 volt battery charge until the charger indicates the battery is full. Your battery is not full, but due to the crystal growth it can't retain more energy. Turn off the charger and remove the battery.
Put your Makita 9.6 volt battery into the power tool. Turn on your device. If your power tool has variable power settings, set it run on the slowest speed, because a slow discharge is better for reviving your battery.
Allow the Makita battery to power your tool until it slows down and eventually stops. Turn off the power tool.
Let the power tool and the battery rest for at least 30 minutes because they need to cool down completely. As the battery cools some of the crystals start to break down and this gives your battery energy.
Turn on your power tool as before. You may find that it has recovered some energy while it rested and cooled. Let it run until it stops again. It probably is not very long.
Turn off the power tool, once it's stopped and let it rest until cool. A few minutes will do it this time.
Try turning on the power tool again to see if it works. If it does, then let it run until it stops and keep repeating the process until it no longer operates. If it does not turn on, your Makita battery is fully discharged.
Complete the revival procedure by putting your Makita battery back on charge. The battery crystals are broken down, so there is greater surface area and it can retain more energy.
Let the battery charge until the charger indicates the battery is full. This time it is full. Notice how much longer the battery took to charge: The longer it takes, the better the revival. Turn off the charger and remove the battery. Use your revived battery as normal.