The MODEL 42 contains an integral high power
resistor load bank which is switched across the battery
via a high power contactor. The contactor is operated
from the control electronics allowing the load to be
applied and removed in accordance with the automatic
test sequence, this ensures no power is drawn from the
battery when the croc clip leads are first connected.
Before beginning a test, the user sets the size of
the battery being tested on a front panel control, this
automatically sets the internal calibration of the tester
to match this battery size.
The test sequence begins when the START push-button
is pressed, this closes the contactor applying the 100A
load to the battery for 5 seconds (to remove any surface
charge that may remain from the last re-charge). If
the battery voltage falls rapidly, as may be experienced
with a flat or faulty battery the load is automatically
removed. At the end of the 5 second load period the
battery is rested for a further 15 seconds, this allows
the battery voltage to recover as the open circuit voltage
is sampled to check the battery charge level. The charge
level is then displayed on a 5 bar yellow led display
in 20% increments.
At the end of the first 20 seconds, the battery is
load tested again to establish the batteries condition.
The on load voltages measured during the on load test
sequence are compared with the internal calibration
settings and the test result is displayed on a coloured
LED display. (See
testing a battery)