Q01-4000
Rev G Page 8 of 28 Teledyne Battery Products
COMPONENT MAINTENANCE MANUAL
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5. CHARGING
5.1
OVERVIEW
5.1.1
Please review the charging method (Constant Current or Constant Voltage)
before commencing. The preferred method is Constant Voltage. Refer to Section
5.2 and Section 5.3.
5.1.2
Correct charging is very important and will affect the overall life of the battery.
The charging process is not 100% efficient due to losses resulting from internal
resistance and will typically require 10% to 20% more recharge than the amount
of capacity removed during discharge.
5.1.3
Undercharging occurs when the battery is repeatedly subjected to time-limited
charging; allowing residual lead sulfate to eventually increase in the plates,
making it difficult to fully recharge the battery. In this case the battery will suffer a
permanent loss of capacity.
5.1.4
Overcharging generally occurs when either constant-current charging is used
without adequate control of total time on-charge or the voltage limit in constant-
voltage charge is higher than the recommended range (see Section 5.2.4).
Overcharging a battery will corrode the positive grids and break-down the water
component in the electrolyte to hydrogen and oxygen (electrolysis). This is quite
detrimental to the life of VRLA batteries since the water cannot be replaced.
5.2
STANDARD CONSTANT-POTENTIAL (OR CONSTANT VOLTAGE, CP OR CV)
5.2.1
These chargers are generally designed to provide a constant voltage source,
with selectable initial current rates.
See recommended charger voltage output
in 5.2.4.
Model variants provide selectable charge voltage and initial charge
rates. Higher output current will reduce recharge time.
5.2.2
CV charging will result in a high initial charging current which will start dropping
off when the voltage gradient between the charger and battery begins to
decrease because the current in any circuit is directly proportional to the voltage
gradient across that circuit.
5.2.3
Typically, the charger will regulate to around 28.6V for 24V batteries or 14.3V for
12V batteries. As the battery approaches the charger output voltage, charge
current will drop below 0.5 amperes.
5.2.4
The battery must be connected to the charger with output voltage set between
28.2V up to 29.0V for 24V batteries and left on until the charge rate drops below
0.5 amperes. At this point, disconnect the charger from its power source first
before disconnecting the battery from the charger – to eliminate any sparks.
