How To Fix A Dead Makita Battery

Cordless tool batteries are certainly a requirement in order for us to be able to use cordless power tools like a cordless power drill, hedge trimmer, leaf blower and many more. When buying a cordless power tool for your household projects, keep in mind that battery voltage is not the only important factor to consider. Other factors such as the battery's amp/hour capacity as well as its type should not be taken for granted when purchasing batteries for your cordless power tools.
Makita makes numerous power tools for both the professional tradesman and the home handyman. Modern battery technology provides battery packs that produce energy similar to the wired variety. Makita first produced battery packs using nickel cadmium (NiCad) cells and then introduced nickel metal hydride (NiMH) cells. While NiMH cells do not present the same problems as NiCad batteries, they can suffer from voltage reduction. Voltage reduction occurs in NiMH cells as a result of not discharging and recharging the battery properly. When the output voltage of the battery drops, the device it powers is underpowered. Restoring a Makita NiMH battery is simple.
Remove the cover from the Makita battery pack. Most covers are held in place using small Phillips screws, so use a suitably-sized Phillips screwdriver. However, if you find your Makita battery is a sealed unit, its best not to force it open as you will damage the pack, and it could be dangerous. Gets a replacement this time, ensuring it has a removable cover?
Use a voltmeter to check the voltage from each cell. Good cells produce 1.2 volts: bad cells have lost their power. Attach the sensor on the end of the red wire from the voltmeter onto the positive terminal of a battery cell: Then attach the sensor on the end of the black wire onto the negative terminal of the same cell. The positive terminal is labeled "+" and the negative terminal "-."
Read the display on the voltmeter. If it says between 1.1 and 12 volts the cells is good. If it reads less than 1.1 volts, you need to replace it. Make a mark on the cell with a pen, so you know which ones are bad. Repeat the process on each cell. Label bad cells.
Charge your dead Makita battery using the charging unit. Once charged, remove it from the charger and leave overnight. You need to find out if any of the cells need replacing and bad cells lose their charge quickly.
Write down how the cells are placed into the battery casing and which cells are soldered together, taking particular note of the cell polarity. You will want to make sure that you maintain the correct polarity positions during reassembly.
Purchase new matching cells at a local electronics or hardware store. Only replace size "C" Nicad batteries with the same type of battery. The Makita battery pack should not be restored by mixing Nicad, lithium and NiMH batteries within the chain.
Insert the battery into its charger. Turn on the battery charger. Let the battery charge until full. This takes a while, as the battery is completely discharged. Remove from the charger. Now the battery is fully restored.
Turn on the device. You will find the Makita battery has recovered power -- the device won't run at full speed, but it will still operate. Wait until the device stops again, and turn off. Let the battery rest for about 5 to 10 minutes.