Battery Testing - Powertronix Quasar Service Manual

Service Manual
The polarization voltage will disappear once loaded, but can lead to misleading terminal voltage
measurements.
To use the open circuit voltage of a battery as a guide to its capacity it must have been disconnected
for at least 72 hours. This measurement is taken off load and can only be used as a guide, it will not indi
cate a battery with high internal resistance.
Float voltage
The float voltage of each battery connected in a series string, is determined by its impedance, relative
to other batteries. The voltage measured at each battery while on charge can give an indication to its
serviceability A battery on charge taking above the minimum float current, will have a different voltage
distribution to one that is fully charged. This measurement can therefore give an indication of the charge
of the battery however a valid voltage reading can only be obtained if the battery has been on float
charge for at least 48 hours.
For maintenance purposes, the ideal is to check the float voltage of each battery before shutting the UPS
down, if the test is carried out after shut down, the reading will not be valid until the float current normal
izes back to its original level, prior to shut down.
It is recommended that a float voltage check is carried out on the unit if a battery problem is suspected,
a defective battery will normally give an abnormal terminal voltage.

6.2.2 - Battery Testing

When working on batteries, regardless of size, remember they have considerable energy content under
short circuit conditions.
They cannot be switched off or isolated as is normal in electric circuits.
WARNING
RISK OF DEATH, SHOCK OR BURN. WHEN THIS BATTERY IS ASSEMBLED, IT IS A SOURCE
OF 390 VOLTS.
Caution
Use extreme care to ensure that batteries are not accidentally short circuited by tools, rings,
watch straps etc.
Use insulated hand tools.
Wear eye protection during handling of batteries.
Before tightening or making connections on battery strings, ensure the battery is isolated
from the UPS circuit and is earth free.
In the event of a battery breakage occurring, dispose of in a container resistant to sulphuric
acid.
Should electrolyte contact the skin, wash the affected area immediately
Site testing
It is not normally possible to check the float voltage of the battery string prior to turning the UPS off, but
the float voltage may need to be checked subsequently.
Float voltage test
Batteries on float below 13.0 V per I2V battery will ultimately sulphate.
Batteries above 13.8 V will have a short service life, and indicates a deteriorating cell.
Investigate the serviceability of batteries with a float voltage below 13.4 V and above 13.98 V If the aver
age float voltage is at the correct level, check and replace if necessary any batteries that fall outside the
float voltage parameters.
Visual examination
3x3 UPS Maintenance
Issue 2 - November 2001
1. After shutdown examine the batteries for the following:
Chapter 6 - Maintenance
Battery Maintenance
6 - 7