SCADAPack Controllers

The Accutech Battery Voltage threshold

The battery voltage threshold will be temperature dependent as well as other dependencies listed below. A lower voltage threshold is required at low temperatures to ensure a fresh battery is not detected as a failing battery. When checking the battery voltage, the BAT VOLT command needs to be used from the Diagnostics menu using the push buttons. Using a multi meter will not yield effective results as the feild unit will not be under load. If the field unit is NOT connected to a base radio (field unit displays NO RF), then the field unit will display "-. V" as the current operating voltage.

These thresholds will also give the customer adequate notification time as the RF card will operate down to 2.44 volts prior to resetting. The temperature is not interpolated, so there is a step change in the voltage threshold at the break points. Here are the thresholds for firmware version 2.00H and earlier.

Temperature Range (C) Voltage Threshold (VDC)
temperature < -20 2.6
-20 <= temperature < 0 2.7
0 <= temperature < 20 2.8
20 <= temperature 2.9

For firmware versions 2.01 and later, the following table applies. 

Temperature Range (C) Voltage Threshold (VDC)
temperature < -30 2.6
-30 <= temperature < 10 2.8 + 0.005*(T-10)
10 <= temperature 2.8

For VC10 field units, there is only one threshold and it is 3.0 VDC.

The field unit indicates low battery if the battery voltage is below these thresholds for more than 2 consecutive measurements. Field units take a sample of the battery voltage once per hour. In some cases a battery can yield a LOW BAT condition due to passiveness with Lithium batteries. Cell passivization is a small film that can develop on lithium batteries when they are new, or have not been used in some time (could only be a few hours). It may take up to 24 hours on a filed unit with a C-cell battery before the passiveness film is removed by normal operation. It could be longer for D-Cell batteries. In general it is best to wait 24 hours if testing a used battery.