4 Operating From a Personal Computer
Operation Guide Flatpack MCU,
351300.013, v8-2006-07
51
4.10.2.1 Functional description – Standard Battery Test
Prerequisites for the test are:
1) The currents to the load and batteries are measured / identified
2) The correct discharge table for the batteries is selected
3) The Max. test duration is set higher than the expected time needed for the batteries to reach the battery End
Voltage.
The first requirement is inherently met by the MCU (the discharge current is accumulated every 20 seconds). The other
requirements must be met by correct setup of the battery discharge table and test parameters by the end user. The
Flatpack MCU must be configured (in a battery table) to ensure that the Standard battery test works as intended. The
Flatpack MCU is pre-programmed with three default battery tables, and one user-defined battery table is available (in
Battery Setup). The battery capacity is calculated as the ratio between the actual test time and the expected test time
with an average current, as specified in the discharging table. When the test is completed, the average discharge current
per battery bank is calculated and the battery data table is used to interpolate the ”ideal” discharge time for the given
current. Battery ”efficiency” is calculated as Test duration/Ideal discharge time for the average current
Test termination criteria are:
• End-voltage – this is the only termination criteria that will calculate a Test result and/or give an alarm.
• Test time – Test result will be overwritten by next test
• Aborted by user - If the test is aborted or interrupted, there will be no alarm, due to an incomplete test. The test
result will then be overwritten by next test.
In order to acquire a valid battery quality result, the test must terminate due to reaching the specified End Voltage, and
not be terminated due to an elapsed Duration value.
The battery test sequence is as follows:
1) The Flatpack MCU reduces the DC voltage from the rectifiers to approx. 45 V (The entire load current is thus
supplied by the batteries).
2) The Test start time commences.
3) The Flatpack MCU measures the average current supplied to the load (at a 20 second sampling rate).
4) The test is stopped when the battery voltage has dropped to the battery End Voltage, or the timer has counted
down to Max. test duration time. The test should be aborted and repeated if Max. test duration occurs.
T1 T2 t
A
T1 = Real Time
T2 = Time supposed to last,
as per the discharging table
Discharging Characteristic
Discharging current vs. time, for a specific end voltage
The Battery Test Alarm Limits, with Capacity in Percent = [T1/T2] *100, are defined as:
Capacity > 80 % ⇒ Battery condition is OK
Capacity < 80 % and > 75 % ⇒ Pre-alarm
Capacity < 75 % ⇒ Battery Test Alarm
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