The decrease in the capacity
of a battery that occurs when
no load is connected. A flooded battery
loses 1% per day, an AGM battery and
Gel battery 2 % per month and a Lithium
Ion battery less than 3 % per month.
The higher the ambient temperature,
the more self-discharging will occur.
Current leakage due to intense pollution
or humidity between the poles can also
cause a higher level of self-discharging, so
you should always keep the top of your
batteries clean and dry.
A semi-traction battery has fewer but
thicker plates in each cell, compared to
starter batteries. Semi-traction batteries
supply a relatively lower starter current,
but can be discharged more often and to
a greater extent (200 to 500 full cycles).
This kind of battery is highly appropriate
for the combined function of starter/
A series connection (the positive pole of
each battery is connected to the negative
pole of the next) increases the voltage of
the total battery set. For example, when
two 12-volt batteries with a capacity of 55
Ah each are connected in series, the total
voltage of the set will be 12 + 12 = 24 volt,
while total capacity remains 55 Ah.
The alternation of voltage can be
graphically indicated by a sine wave.
This consists of a line that follows a wave
pattern around a horizontal axis, which
represents the passage of time and also
the points at which voltage is zero. Once
the line has traced one entire wave above
the time axis and one entire wave below,
a whole sine wave has been outlined.
Square millimetre (mm²)
Unit in which cable diameters are
measured. With a direct current system
of 12 or 24 volt, three amps should
correspond to one mm² of cable
thickness. For 230 volt systems allow
6 amps for each mm². Both apply for a
maximum length of 3 metres.
Device used to reduce the inrush
current of transformers and motors.
In this mode the inverter emits a
small pulse instead of the usual
230 volt output. It detects when an
appliance is switched on and then
automatically switches on, supplying
230 volt until the output current falls
below a pre-set value. When there
is little or no output current, this
means that no load is connected and
the inverter switches back to stand-
by. This system saves a great deal of
Mainly used to start engines.
Although these batteries can deliver
a high current, they should not
be excessively or too frequently
discharged and are therefore not
appropriate for lighting purposes.
AGM batteries are ideal to serve as
starter battery and limited cyclic use.
If the battery tempe
rature is lower than 25 ºC, the
charge voltage should be adjusted
upwards. When higher, the charge
voltage needs to be reduced. This
temperature correction is 30 mV per
ºC for a 12 Volt battery and 60 mV
per ºC for a 24-volt one. While this
may seem insignificant, it is essential
to ensure a long battery life.
A temperature sensor should be
attached to the battery so that
the charger can optimise charge
voltage with respect to the battery
temperature. The charge voltage
depends on the battery temperature
(see also Temperature correction).
Used for propulsion, powering
equipment and inverters, etc. They can
be discharged often and completely, and
in a Gel version are highly suitable for
onboard use. Flooded cell batteries are
only appropriate for forklifts, etc.
A (frequently automatic) system used to
switch between multiple power sources,
such as grid, generator and inverter.
An American certification
provided by Underwriters
Laboratories that is similar to the
mark and mainly
focused on safety
Unit in which electric potential
(voltage) is measured.
A modern charging technology that
has been extended with an extra
step in Mastervolt equipment,
the Plus phase.
The three steps are:
Bulk, where the charger supplies
Absorption, during which the
charger delivers maximum charge
voltage and the battery is charged
from around 80 % to 100 %.
Float, used for battery
maintenance and delivering power
to connected equipment.
The ‘plus’ phase is an automatic
one-hour bulk phase once every
12 days when the battery is not