Varta 56650 764 098, Technical Handbook

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9
3.1 Definitions and Standards
BASICS
Unless otherwise stated the technical values and definitions are based on room temperature
conditions (RT = 22°C ± 3°C).
VOLTAGE DEFINITIONS
Open Circuit Voltage (OCV):
is the difference of electrical potential between
two terminals of a device when disconnected from
any circuit, dependent on battery model,
temperature, storage duration and state of
charge.
End of Discharge Voltage (EoD):
The voltage at the end of discharging depending
on discharge rate and temperature.
End of Charge Voltage (EoC) should also be
referenced from the individual specifications.
CAPACITY DEFINITIONS
The capacity C of a cell is defined by the
discharge current I and the discharge
time t: C = I * t
I = constant discharge current
t = duration from the beginning of discharge until
the end of discharge voltage is reached
Nominal Capacity: The nominal capacity C
denotes the capacity amount in Ah (Ampère
hours) that the battery can deliver at the 5h
discharge rate (0.2 C). The reference
temperature is +22°C ± 3°C, if not otherwise
stated and the final discharge voltage will also be
stated.
Available Capacity:
Factors which affect the available capacity are:
►
Rate of discharge
►
End of discharge voltage
►
Ambient temperature
►
State of charge
►
Battery age
►
Cycle history of the battery
At higher than usual discharge rates the
available capacity is accordingly reduced.
CURRENT DEFINITIONS
Charge and discharge rates may be given as
multiples of the Rated Capacity (C) in Ampères
(A) with the term C.
Example:
Rated Capacity C = 1000 mAh
0.1 C = 100 mA, 1 CA = 1000 mA
Nominal Discharge Current:
The nominal discharge current of an ASB battery
is the 5 hour discharge current (0.2 C). It is the
current at which the nominal capacity of a cell is
discharged in 5 hours.
I = C/t = C/5 = 0.2 C when t = 5 h