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8.4 BATTERY TESTING
The batteries are by far the most likely component in any UPS to fail. Loss of the batteries results in a
power outage to your load as soon as the next power failure occurs. With most UPS’s you don’t know
you have bad batteries until such a power outage occurs, which is too late. Mesta incorporates one of
the most advanced battery diagnostic tools available in the market to detect battery problems before a
power outage occurs. This allows the faulty batteries to be replaced before they cause your critical
loads to crash! To test any battery, one must draw current from the battery while measuring the voltage
output of the battery. A battery that has reduced capacity will exhibit a reduced voltage compared to a
good battery. Even worse than a reduced capacity battery is a battery that has very high impedance.
Such a battery may not be able to deliver any sizable amount of current. A UPS having such a battery
in its bank will result in the bank being unable to support the critical load for even a fraction of a second.
It is important to detect such problems as soon as possible; otherwise, the critical load is at risk of
crashing at the next aberration in the utility voltage.
The Mesta UPS includes comprehensive battery tests that allow early detection of such battery
problems. During these battery tests, current is drawn from the batteries without having to turn off the
utility. Should a problem be observed during the test, the UPS immediately stops drawing current from
the batteries and resumes recharging. The UPS will draw current from the batteries up to the amount
needed to support the load. If a load does not exist or is very small, the Mesta UPS is capable of
drawing current from the batteries and delivering the power back to the utility, thus using the utility as a
load.
Such tests may be performed either manually, using the Manual Battery Test (refer to section 5.3.4 for
details) or regularly scheduled Automatic Battery Tests (refer to section 5.3.6 for details). Generally,
you should set up your system to perform Automatic Battery Tests at regularly scheduled intervals.
Should the automatic tests find a problem, the UPS will issue a “Warning” annunciation. This will
consist of a “BATTERY PROBLEM FOUND DURING LAST TEST” Warning message displayed on the
LCD, the Red ATTENTION light on the front panel being lit, and an audible alarm being generated. In
addition, if your unit is equipped with an optional remote annunciation feature, an indication of a
pending problem will occur. This “Warning” annunciation will continue to exist until either a Manual or
Automatic Capacity test is re-run with favorable results, the warning is reset via the
DIAGNOSTIC/WARNINGS reset on the SYSTEM RESETS LCD screen (refer to section 5.2), or the
UPS is shut off.
The results of the last manual battery test are stored in battery backed-up memory and can be
observed by pressing the <SELECT> key on the front panel keypad and selecting item 6, “MAN
BATTERY TEST”. Once a new manual battery test is started, this display will show the active test
results. The results of the “Quick” and “Capacity” automatic battery tests are archived in battery
backed-up memory. The last 20 tests of each type are saved and can be viewed by pressing the
<SELECT> key on the front panel keypad, selecting item 7, “VIEW HISTORY”, and selecting item 5,
“BATT TEST Q”, or item 6, “BATT TEST C”, to display the results of the last 20 “Quick” or “Capacity”
tests, respectively. Both the Manual and Automatic battery test result displays have a “RESULT=”
display. Following is a list of possible messages for this display:
RESULT message
Description
TEST PASSED
Test reached its desired duration finding no problems with the batteries
FAIL-WARNING
% charge fell below the failure level, indicating batteries have reduced
capacity capability. Batteries may need to be replaced. Call for service.
FAIL-DIAGNOST
Battery voltage dropped dramatically to levels indicating that the batteries
are in very bad shape and should be serviced immediately. Verify this
failure by running a manual battery test
OPERATOR ABORT
Operator ended the manual test (by either selecting STOP from the manual
