4 Maintenance
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Alpha Technologies
4.1 Measuring the Battery Backup Time
This test measures how long the batteries can provide backup power by having them power the
loads until they are discharged. Because it is load dependent, the time to do it out varies.
Tips:
• This test should be done once a year when the batteries are new. When the batteries are
three years old or older, it should be done once every three months.
• The unit should have been in line mode for 24 hours before starting this test so that the
batteries are fully charged.
• Refer to Figure 3.6, “Battery Discharge States” (Section 3.10) to understand the various
stages the batteries and the unit goes through as the battery discharges.
Procedure:
Turn off the input
circuit breaker.
The
On Battery
(50%) LED turns
ON
.
Record this start time
Record when the low
battery warning
appears.
Add 10% to the
elapsed time. The
total is the battery
reserve time.
Turn on the input
circuit breaker to
return the unit to line
mode and charge the
batteries.
Start
Backup Time Testing Finished
EXAMPLE
Start time is
1pm
.
The low battery warning
appears at
2pm
.
Add 10% or 6 min to
this time, for a total of
battery reserve time of
1 hour and 6 min.
