Maintained capacity
The battery is kept in a fully charged state by means of a constant voltage charger with a low charging voltage (compensates for self-discharging).

Maintenance-free battery
>> Battery, maintenance-free; >> Maintenance-free battery with fixed electrolyte.

Maintenance-free battery with fixed electrolyte
Lead-acid battery in which the electrolyte is held in place in a gel or microglass mat (AGM). The battery is sealed and is equipped with valves.
It is highly stable and exhibits good cycling characteristics.

Marking machine
Mostly using a hot stamp, marks the battery in a way, that the manufacturer can trace back the whole production history of the battery.

Mass, active
The material in the electrodes hat takes part in the charging and discharging reactions. In the nickel-cadmium cell, nickel hydroxide and cadmium hydroxide
are used as active mass at the positive and negative electrodes. In the lead cell, lead dioxide and sponge lead serve as the active mass at the positive and
negative electrodes. The sulphuric acid in the lead cell which functions as an electrolyte can also be considered as an active mass, because it also takes part
in the cell reaction.

Mixer
>> Paste mixer

Mould, casting
A component made of cast iron or steel in which the required geometry of the mould takes the form of a cavity (e.g. casting mould for producing lead grids).

Monobloc battery
Multi-cell battery in a block box. >> Battery case.

Mud
Material which scales or sheds from the positive plates and collects in the container wells.