ETS-Lindgren HI-6006, User Manual, Page: 89 / 92

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predetermined acceptable limits. A pulse-trickle charge is provided to
bring a depleted battery to a valid charge prior to fast charge.
• CHARGING (amber)—Indicates the voltage pre-qualification condition
has been met, and fast charge has started. Fast charging continues
until termination by a peak voltage detect or a maximum charge time.
For peak voltage detect, the fast charge is terminated when the battery
voltage is lower than the previously measured values by 24mV. If a peak
voltage is not detected, then the fast charge is terminated when the
maximum time limit of 180 minutes is reached.
• COMPLETE (green)—Indicates a fast charging peak voltage is detected.
If the probe is turned on during the fast charge period of the charge
cycle, the current surge that the batteries provide to the electronics in
the probe will cause a momentary voltage drop on the batteries, causing
the charger to terminate the fast charge based on a peak voltage detect
condition.
The battery charger switches to top-off charge mode that provides a charge
current one-eighth of the fast charge rate. This charge continues from
the time when a peak voltage detect terminates the fast charge, until the
maximum time of 180 minutes is reached. If the probe is disconnected
from the charger at this point in the charge cycle, the batteries will operate
properly.
Following the maximum time of 180 minutes, a pulse-trickle charge mode is
used to compensate for the self-discharge of the batteries while idle in the
charger.
The fast charge current is low enough that there is not always enough
heating of the battery cells to cause the voltage to drop. With no voltage
drop there is no peak voltage detection, and the fast charge will terminate
after the maximum time of 180 minutes is reached.
Synchronizing The Battery Charge Indicator
The probe has internal circuitry to track the charge condition of the
batteries. NiMH batteries have a sharp discharge-curve knee, which means
there is little indication that the batteries are nearly discharged prior to
a low battery condition. The internal circuitry tracks the charging and
discharging currents of the batteries and displays the calculated battery
condition.
It is possible that the battery charge indication may lose synchronization
with the actual battery condition. A loss of synchronization may be indicated
by a low battery charge alert after the batteries were recently fully charged.
Loss of synchronization may also be indicated by short battery life and
premature low battery alert.