VOLTCRAFT RIM 1000 Bedienungsanleitung Seite 26

The higher the load current, the lower the resistance of
the load and the more a voltage drop makes itself
noticed on the accumulator internal resistance.
With a multi-cell accumulator, the internal resistances, of each
individual cell are added up to become a total resistance. If you
compare the voltage on a fully loaded accumulator to a dis-
charged accumulator (no lowly discharged), you will establish
that there is only a low difference in voltage.
The difference under load conditions, however, is appreciable.
That shows that, during the discharge process, the voltage
release of the source of voltage scarcely alters while the internal
resistance rises markedly particularly at the end of the discharge
process.
To determine the internal resistance of accumulator or
the accumulator pack, these have to show a defined
load status.
As a rule, the accumulators should be almost fully
charged. The same load status is particularly impor-
tant if a balancing of different cells is to take place.
Apart from a defect and thus total failure, the ageing of an
accumulator makes itself noticeable through nothing else but an
increase in the internal resistance.
On the basis of the discharge curves, it is possible to determine
how the internal resistance of an accumulator or accumulator
pack alters during the discharge process and also during ageing.
Desirable is a high voltage situation during the complete dis-
charge period. Good cells show a fairly steep drop in voltage only
at the end of the discharge curve.
Discharging accumulator 1 (1.5A)
Discharging accumulator 2 (1.5A)
Figure2: Discharge curves of four different accumulators
26
Discharging accumulator 2 (1.5A)
Discharging accumulator 4 (1.5A)