OPERATING PROCEDURES FOR MODEL MBC8 BATTERY CHARGER
GENERAL The Model MBC8 Battery Chargers are constant voltage, two rate (Float-Equalize) manually switched,
regulated (line compensated) battery chargers.
OUTPUT CAPACITY These Chargers are capable of supplying up to 100% of their DC rated output current without
allowing the battery to be depleted. Loads across the battery which are less than the Chargers rated current will be
supplied by the Charger with the remaining Charger output being available to charge the battery, if required. For loads
greater than the rated output, the Charger will supply at least its rated output (if the crank disconnect terminals--DK1 and
DK2--are not energized) with the battery supplying the remainder.
LINE REGULATION The Charger is regulated (line compensated) and requires no tap settings.
The line voltage regulation (output change) is 1% maximum for a 10% line voltage change. The Charger will operate with
line changes of up to + 15% of nominal with reduced current rating on low line voltages.
WATER CONSUMPTION In the "float" mode water consumption will be low. If left in the "equalize" mode the Charger will
produce considerable gassing and subsequently high water consumption once the battery is fully charged. THE
CHARGER SHOULD NOT BE LEFT IN THE "EQUALIZE" MODE FOR EXTENDED PERIODS OR BATTERY DAMAGE
CAN OCCUR. The battery water level should be checked once a month until a water consumption pattern is established.
The water level should be checked at least every three months due to climatic changes. Longest battery life will be
obtained when distilled water is used to fill batteries.
FLOAT MODE This is the NORMAL operating mode of the Charger, in this mode the Charger will maintain the battery
charge level, supply external loads up to the Charger output current rating and will bring the battery up to a charged
condition after a discharge. Water consumption will be low in this mode. With no external loads the final or maintaining
current into a fully charged battery will be less than 0.5 amperes.
EQUALIZE MODE For batteries within the recommended range of capacity (ampere hour capacity of 5 to 20 times the
Charger output current rating) the Charger will have sufficiently high output voltage and current to equalize a battery to
eliminate charge level differences between individual cells. The equalize mode can also be used to charge the battery
more rapidly. Most applications do not require equalizing the battery more often than once a month.
On engine starting applications the battery charging generator or alternator will equalize the battery if the engine is run long
enough for the battery to be fully charged first.
THE CHARGER SHOULD NOT BE LEFT IN THE "EQUALIZE" MODE FOR MORE THAN 24
HOURS OR EXCESSIVE WATER CONSUMPTION AND BATTERY HEATING WILL OCCUR.
CRANK DISCONNECT In applications requiring battery output currents which exceed the Charger output rating, such as
engine cranking, a crank disconnect signal must be supplied to the Charger. This signal should be a DC voltage of the
same nominal value as the Charger DC rated voltage. The signal may be either polarity and is supplied to terminals DK1
and DK2. The current required by the disconnect relay is less than 20mA on 12 volt units and lOmA on 24 volt units.
Wiring these terminals to the starter contactor or starter motor terminals would provide the required signal on engine
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