VOLTCRAFT RIM 1000 Bedienungsanleitung Seite 27

The discharge curves of four different 9.6-volt accumulator
packs were recorded under the same discharge condition and
can be seen in figure 2.
If voltage collapses occur during the discharge process, it is a
clear sign that not all cells have the same capacity or one or more
cells are already damaged /clearly to be seen in accumulator 2).
During the continued discharge course, re-poling can take place
and thus further damage to this cell.
Well-selected cells always make sure that accumulator
packs have a high level of reliability and, in particular,
a long service life..
If you put together an accumulator pack yourself, different cells
(different type or manufacturer) should never be used together and,
above all, no cells of different capacity (e.g. 1200 mAh + 1300
mAh). The better you select the cells, the better and longer the
service life of the accumulator pack made up from them.
The ageing status of an accumulator can often not be recognised
clearly on the basis of a capacity measurement. On the other
hand, the measurement of the accumulator's internal resistance
will give you a far more exact picture if the charge status is
defined.
The internal resistance is therefore the most powerful
riterion for the resilience of an accumulator.
For example, for so-called "sub-C" cells, typical values
can be found in the range from 4 mΩ to 6 mΩ.
But the internal resistance of an accumulator is not responsible
alone for the loss of voltage. In a system operated with accumu-
lators (e.g. for a RC car or a motor sailor) there are other, stray
resistances in addition (e.g. the cables or plug connections.
In the course of time, contact resistances can be
appreciably increased/decreased through poor contact
(contacts arched) or contamination or oxidation on
plug connections or screwing. At a high current load,
appreciable loss of voltage ensues for these reasons!
As a rule, these contact resistances remain unchanged towards
each other. For high-current applications, it is therefore always
worthwhile to carry out optimisation by doing without unnecessary
plug situations and using cables which are as short as possible
with a large cross-section. Plugs, jacks and plug connectors
should show a large contact area and have a firm seating. Gold-
plated contacts are recommended.
27