Accuracy of battery status indicator – NARDA 8718B User Manual

Page 78

Advertising
background image

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.

Advertising