Milwaukee Milwaukee M12 battery system

M12 is a 12 volt battery system from Milwaukee which is used in over 100 power tools.

The batteries are "push-in" style meaning that they fit inside the handles of the tools making the handle a bit bulkier, but reducing the overall size of the tool compared to systems that use an entirely external battery.

Milwaukee M12 tools are renowned for being high quality and being more powerful than 12 volt tools from other brands; however more power often comes at the expense of battery life.

The battery packs contain three 3.6 volt 18650 Lithium-Ion cells in series to produce 10.8 volt output. When fully charged the voltage can reach up to 12 volts. That is why this battery system, like several others, is marked as 12 volts but actually has a nominal rating of 10.8 volt.

Some M12 tools have the addition "FUEL" to their name to indicate that they have better performance, but is unrelated to the battery system.