Nortel DMS-100 Series Maintenance Manual page 54

1-38 OPM maintenance summary
Intermittent charging design
The OPM uses an intermittent charging design that the battery rotation and
testing audits implements. Do not confuse the OPM intermittent charging
design with the float or cyclic charging designs. Other battery application
manuals refer to the float or cycle charging designs.
A float charging design applies a constant voltage to the batteries to:
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During cyclic charging, the batteries are discharged between each charging
cycle. The OPM batteries are deep discharged during an extended ac outage.
The OPM intermittent charging design operates in the following way. The
batteries are held on the system load bus at a voltage above the open circuit
voltage of the battery. The voltage is -52V dc for the Yuasa A037761 and
Eagle-Picher A0386201 battery. The voltage can maintain the batteries in a
completely charged state. This voltage also recharges the batteries to between
90% and 100% after a discharge. The voltage cannot prevent the accumulation
of sulfate deposits on the battery plates. The batteries are regularly moved
from the load bus to the charge bus for a short period of time. The charge bus
voltage makes sure that the batteries are charged to full capacity. The charge
bus voltage also forces sulfates that have accumulated on the battery plates,
back in the liquid.
The OPM intermittent charging design, is more complicated than the easy float
charging design. The OPM intermittent charging design offers the following
advantages:
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Intermittent charging reduces the following to increase battery life:
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297-8361-550 Standard 04.02 December 2004
keep the batteries completely charged
completely recharge the batteries after discharge
prevent the accumulation of sulfate deposits on the internal battery plates
Extended battery life
Tests show that battery life can lengthen by 50% to 100% when
intermittent charging is used instead of float charging. Lead-acid batteries
are sensitive to temperature. Each 7°C to 10°C (45°F to 50°Φ)
τεµπερατυρε ινχρεασε αβοϖε 25°C (77°F) reduces the battery life by
50%. The OPM internal temperature is an average of 12°C to 15°Χ (54°F
to 59°Φ) αβοϖε ουτσιδε αµβιεντ τεµπερατυρε.
load bus voltage
battery-charging current
battery internal temperature rise
rate of battery-positive grid corrosion