C&D Technologies RS-1476 Standby Battery Vented Cell User Manual

Page 16

AC Ripple
Commercial battery chargers convert ac electrical energy to dc. The conversion, however, is not perfect, and

some voltage variation remains in the output voltage and current. This is known as ac ripple. The frequency and

magnitude of the ripple depends on the design of the charger and the filtering included in the supply. Lead acid

batteries act as a filter for ac ripple, and any variable energy delivered to the batteries is converted to heat. If the

magnitude of the ripple is high enough, shallow charge and discharge cycles may take place.
The impact of ac ripple on flooded battery performance and life has been studied; however, there are few

conclusions with regard to recommendations for maximum ripple voltage. It is clear that any voltage variation

that forces the batteries between gassing and discharge voltages may have an adverse effect on product life.

The key parameter is the difference between the float voltage setpoint and the product open circuit voltage. If

the charge voltage falls below the unit open circuit voltage the batteries will discharge. For most C&D flooded

products the difference between float voltage and OCV is between 6% and 8% of the recommended mid-range

float voltage.
We recommend limiting the maximum ac ripple voltage in a charge circuit to 6% of the recommended mid-range

float voltage to avoid issues with shallow cycling of the batteries while on float.
Contact C&D Technical Services Department for additional information on calculating allowable ac ripple voltage.

PART 2

CHARGING AND OPERATION OF BATTERY

SECTION 1 - CHARGING BATTERY
1.1 Initial Charge
All batteries shipped wet and fully charged lose some charge in transit or while standing idle before installation. At

the first opportunity, they should be given an initial charge (boost), using either the constant voltage method or the

constant current method.
Lead antimony batteries must receive an initial charge (boost) within three months of shipping date from the C&D

factory when stored at 77°F (25°C). Batteries not placed in service following an initial charge should be recharged

every three months up to a maximum of one year from date of shipment from C&D’s factory when maintained at

77°F (25°C).
Lead calcium batteries must receive an initial charge (boost) within six months of shipping date from the C&D factory

when stored at 77°F (25°C). Batteries not placed in service following an initial charge should be recharged every six

months up to a maximum of one year from date of shipment from the C&D factory when maintained at 77°F (25°C).
Higher than normal storage temperature 77°F (25°C) will accelerate internal self-discharge of a battery. Self-

discharge will double for every 15°F (9°C) over nominal 77°F (25°C) storage temperature. This factor will shorten the

allowable time before initial and subsequent charging.
Provide an initial/boost charge to the battery at the recommended voltage shown in Table 4.

Table 4 - Initial Charge Voltage and Duration of Charge

LEAD ANTIMONY CELLS

PART 1

RECEIVING AND INSTALLATION (CONTINUED)

Nominal Specific

Gravity

See Part 4, Sec. 1.3)

Maximum Average

Volts Per Cell VPC

(see note)

Time in Hours

at maximum

cell voltage

1.215

2.39

2.36

2.33

2.30

2.24

110

160

210

RS1476/0215/CD