Big factory direct sales, high performance 18V cordless power tool batteries
Lithium batteries are great because they carry a large charge for their weight. Also they can be recharged at any point in the discharge cycle without any memory effects. They discharge extremely slowly if left unused, so can be stored for long period whilst still retaining most of their charge. However, they are different from other batteries in that the discharge has to be controlled with current limiting devices or they will rapidly discharge, overheat and catch fire or explode. Also if they are discharged beyond a certain point they are impossible to recharge. Because of these limitations they normally include a fair amount of electronics within the battery casing to control the charging and discharging and keep the operation of the battery within safe limits.
You could try opening the casing and looking for some obvious disconnection fault, but if the electronic control circuit is faulty you will need an electronics specialist to repair it.
Makita 18V Lithium-ion Makita BL1830 Cordless Drill Battery Repair
Step 1: Dismantling & Inspection – Before we start with the dismantling, remember that even if your batteries do not work anymore they most likely still contain a significant amount of energy. Be careful in how you handle them and above all make sure you do not short them out.
The first step is to get the cover off. This is held on by four T10 Anti Tamper screws, on newer models there may be a white Anti Tamper plug covering one of the screws. I have found that the easiest way to remove it is to drive in a small wood screw and pull it out with a pair of pliers. Once you have the Makita power tool battery open being careful that the retaining clip spring does not fly away or short out the control board you should be able to see if there are any obvious major issues.
Step 2: Testing the Makita cordless tool battery – By way of comparison a known good drill battery seems to measure around 20V when freshly charged. So I decided that my best option to end up with an extra working battery was to change the board on Battery Four as its cells were all pretty close on voltage suggesting it was fairly evenly charged. Up until recently replacement circuit board were not available so once you had seen the red / green flashing lights three times your battery was bricked.
Step 3: Replacing the Control Board – The control board came with ok instructions on how to fit but they don’t explain everything, this may be because it can be used with all of the models of 18V Makita drill battery have made. Providing you have a bit of common sense you should be ok.
So apart from the soldering you might expect you also have to cut away a lot plastic and that’s assuming you are lucky like me and don’t need to replace any battery cells. If you do spot welding to the cells is the best way to go, as if you solder you risk overheating.
Step 4: Putting It to Test – Last came the moment of truth, Batteryfast battery experts put the original Makita tool battery on original battery charger and it charged. We then fully discharged the battery and once again recharged the Makita BL1815 drill battery and that also worked. Eight month on the battery is still preforming perfectly.