NARDA 8718B, User Manual

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77 Chapter 12 Back Light and Battery Status
4. Press the ESC key to return to the First Menu Screen .
Press it again to return to the measurements screen.
Accuracy of Battery Status Indicator
The characteristics of Ni-Cad rechargeable batteries make it
difficult to provide a truly accurate indication of charge level.
This is because there is very little voltage difference over a broad
range of charge levels.
The battery status indicator on the 8718B is reasonably
accurate when indicating charge levels of more than 80% or less
than 20%. Unfortunately, indicated charge levels greater than
20% but less than 80% are only very rough estimates.
It is a characteristic of these batteries to get a large voltage
increase with only a brief charging period if one starts with a
battery that is completely discharged. However, under such
conditions, the battery has very little capacity and the voltage
drops quickly in use. Since the status indicator circuits measure
battery voltage, this can lead to erroneous indications of charge
level when the meter is first turned on. This false indication will
only occur when the batteries do not receive a complete charge.
The battery should be charged for a minimum of eight hours,
but ideally only when the status indicator shows a level of less
than 20%. The back light can be turned on to speed up the
discharge process when desired. These batteries obtain a
maximum charge when charging takes place with batteries
close to fully discharged.