How to Fix a Dead Makita Battery
Makita batteries are used to power their range of cordless tools. The voltage output from each battery depends on the number of cells it contains and the voltage requirements of the power tool. Makita battery packs made from nickel cadmium (NiCad) or nickel metal hydride (NiMH) cells each produce 1.
2 volts wired in series so, for example, a Makita 9.6 volt battery has eight cells. If you find your battery is dead, fix it rather than purchase a new one.
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.
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. Get 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 labelled "+" 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.
Remove the bad battery cells you labelled from the battery pack. Simply pry them out using a flathead screwdriver.
Get replacement battery cells from an electrical store. Take a bad cell with you to the store to ensure you get the same type.
Put the replacement cells into the battery pack. Push them into place using your fingers.
Replace the battery cover. Put the Phillips screws into the holes on the battery cover and tighten using a Phillips screwdriver.
Put your battery on charge for an hour. This makes certain all the batteries are charged.
Turn off the charger and remove the battery. Insert your fixed Makita battery into the device and it's ready to use.