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GLOSSARY:
AGM – Absorbed Glass Mat –
A class of VRLA (Valve
Regulated Lead-Acid) battery in which the electrolyte is
absorbed into a glass mat.
Ambient Temperature –
The average temperature of the
battery room. Temperatures below 77°F (25°C) will reduce
battery capacity. Temperatures above 77°F (25°C) will
reduce battery service life.
Amp Hour (Ah) –
Amps times Hours
Battery Efficiency –
The amount of Ah return required
to achieve full SOC vs. the amount of Ah removed during
discharge. Require 110% to 115% Ah return.
Capacity –
The capacity of a battery is specified as the
number of Amp-Hrs that the battery will deliver at a specific
discharge rate and temperature. The capacity of a battery is
not a constant value and is seen to decrease with increasing
discharge rate.
C20 –
Battery capacity measured in Ah (amp hour) at the
20hr rate.
End Voltage –
The minimum voltage at which a DC system
will operate.
Flooded –
A battery in which the products of electrolysis
and evaporation are allowed to escape to the atmosphere
as they are generated. Electrolyte is free flowing throughout
the battery.
Gel –
A class of VRLA (Valve Regulated Leda-Acid) battery
in which the electrolyte is immobilized in a gel form (sulfuric
acid mixed with silica).
Parallel –
A circuit that provides more than one path for the
flow of current. A parallel arrangement of batteries (usually
of like voltages and capacities) has all positive terminals
connected to a conductor and all negative terminals con-
nected to another conductor. If two 12-volt batteries of 50
ampere-hour capacity each are connected in parallel, the
circuit voltage is 12 volts, and the ampere-hour capacity of
the combination is 100 ampere-hours.
Series –
A circuit that has only one path for the flow of
current. Batteries arranged in series are connected with
negative of the first to positive of the second, negative of the
second to positive of the third, etc. If two 12-volt batteries
of 50 ampere hours capacity each are connected in series,
the circuit voltage is equal to the sum of the two battery
voltages, or 24 volts, and the ampere-hour capacity of the
combination is 50 ampere-hours.
SOC (State of Charge) –
The amount of deliverable
low-rate electrical energy stored in a battery at a given time
expressed as a percentage of the energy when fully charged
and measured under the same discharge conditions. If the
battery is fully charged the “SOC” is said to be 100%.
Temperature Correction –
A factor used to compensate for
battery capacity and/or adjust battery voltage at ambient
temperatures greater than or less than 77°F (25°C).
Undercharge (Deficit charge) –
Charging a battery with less
ampere-hours (Ah) than is required to return the battery to
its initial state-of-charge. This results in a reduction in the
battery state-of-charge.
VPC –
Volts per Cell
VRLA –
Valve Regulated Lead Acid – a lead-acid cell/battery
that is sealed with exception of a valve that opens to the
atmosphere when the internal gas pressure exceeds atmos-
pheric pressure by a pre-selected amount. VRLA batteries
provide a means for recombination of internally generated
oxygen and the suppression of hydrogen gas evolution to
limit water consumption.
