Makita Cordless Power Drill DC7100

20 November 2013

The Makita Cordless Power Drill is a handy tool.  Its power unit consists of a 7.2 volt battery pack and a fast battery charger.   This article describes how to replace the battery and repair the battery charger.



 What’s Needed

1)     For replacement of battery 

a)     Soldering iron,  solders and some connecting wires

b)     4 Nos  of 18650 Li-ion batteries.  Can also use some of the good batteries in Laptop for this purpose




c)     Remove the end cap of the battery pack and withdraw the batteries

d)     Solder the 18650 batteries,  2 in parallel then put them in series to make up a total voltage of 7.4 volts.  Pay particular attention to positive and negative battery terminal and make sure there are correctly wired;  also pay attention to how the resistor is connected. 

e)     Once soldering is completed, wrap the batteries with shrinkable plastic and re-assembled the batteries to the battery pack casing.


2)     For repair of the power charger 

In addition to the soldering iron,   one will need a multimeter that can measure the workings of the A1015 transistor and the 2P4M SCR thyristor.  These 2 components are likely to be at fault.  .  One would need knowledge of electronic repairs for this task.  Use the attached circuit diagram to troubleshoot.

2P4M Thyristor


makita tools said...

Nice info about makita power drill

Anonymous said...

Thank you for the schematic ! I have a no-brand charger that is very similar to the makita.

Anonymous said...


I also just reverse engineered the charger. It has some more details.

Do you really use Li-cells for this battery? how about balancing and voltage cutoff?

greets, Karl