30 November 2004 / Masterlink MICC / EN
12 GENERAL BATTERY
INFORMATION
The lifetime and performance of batteries
depend for a great deal on how they are cared
for and used. Below we have listed some
influences on the lifetime and some more
information about charging and calculating the
right capacity for your system.
Temperature
A high temperature is disastrous for the lifetime
of your batteries. If they are regularly subjected
to temperatures above 40°C you should relocate
them or supply forced fresh air ventilation.
Discharge
Regularly discharging below 20 % of battery
capacity has a negative effect on lifetime. For
long life of the batteries it is best not to
discharge the battery below 50 %.
Charging
Special care must be taken if wet type batteries
are used. During charging they produce
dangerous hydrogen gas. This means that
special care must be take for ventilation to avoid
the danger of explosion.
To keep their capacity batteries must be
charged fully regularly and the best way is to
use a three step regulated charger. To adjust
the charger according to the temperature of the
battery will increase the lifetime of the battery
significantly. Also a low voltage ripple will help
to extend the lifetime of the battery.
Mastervolt therefore recommends the use of the
Mastervolt Mass or IVO Smart chargers.
Charging a battery is simple if 230 V utility power
is regularly available. However using a generator
to charge the battery up to more than 85 % is not
efficient. The reason for this is that the charging
current is strongly reduced after reaching 80-
85% of the battery capacity. A rule of thumb can
be used that the last 20 % of charge of the
battery will take 3-4 hours. To keep the generator
time as short as possible batteries will not be
charged up to the full 100 % if a generator is
used to charge the batteries. Normally this will
not harm the battery as long if they are brought
back to a full 100 % at least every five to seven
days.
Real available capacity
The battery capacity given by the manufacturer
is based on the current the battery can deliver
when fully discharged during 20 hours. Using
the (not absolute) values for charging and
discharging mentioned above (50 % and
100 %) means that about 50 % of the capacity
as declared by the manufacturer is really
available for use. If you often use a generator
this can even be as low as 35 %
Choosing the best battery capacity for your
situation
If you are going to decide about the battery
capacity that you have to install it is good to keep
the above mentioned 50 % in mind. If the batteries
are often discharged at a higher rate than 5 % of
the battery capacity (C 20 rate) as given by the
manufacturer, it is also useful to take the Peukert
effect into account. The 50 % rule and Peukert
effect result both in larger battery sets as expected
after simply counting factory specifications.
However if you take both into account you will
miss the often heard disappointment about the
performance of batteries.
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