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Appendix D – Inverter/Charger Terminology
Appendix D – Inverter/Charger Terminology
The following is a glossary of terms with which you may not be familiar. They appear in the
various descriptions of inverter and battery charger operation.
Absorption Stage
– In this second stage of three stage charging, the batteries are held at a
constant voltage (the absorb voltage setting) and the battery is charged to its maximum capacity.
AC (Alternating Current)
– Electrical current that varies with time (i.e., shorepower). The rate
at which the voltage changes polarity is the frequency in Hertz (Hz).
Ampacity
– The ampacity of a wire is its current carrying capacity with reference to the cross-
sectional area of the conductors, the temperature rating of the insulation and the ambient
temperature.
Automatic Transfer Relay (inside the inverter)
– An automatic switch that switches between
Inverter and Standby mode depending on availability of AC input power. If AC is present, the unit
will be a battery charger and pass power through the inverter. When the AC goes away, the unit
becomes an inverter.
Bulk Charge Stage
– The
fi
rst stage in three stage charging. In this stage, a constant current is
fed to the batteries and as they accept the current the battery voltage will rise.
CEC
(Canadian Electrical Code)
– The guidelines and acceptable practices for electrical
installations in Canada.
Current (Amps)
– The amount of electricity
fl
owing through a conductor.
DC (Direct Current)
– Electrical current that does not vary with time (i.e., battery voltage).
Deep Cycle
– A deep cycle occurs when a battery is discharged to less than 20% of its capacity
(80% depth-of-discharge).
Deep Cycle Battery
– A battery designed to be routinely discharged to 20% of its maximum
capacity without damage. This type of battery is recommended for use with an inverter system.
Derating
– As an inverter (or charger) is used above its normal temperature, it’s capacity to
power loads (or charge) continuously is decreased.
Digital Volt Meter (DVM)
:
True RMS
– A voltmeter that incorporates a RMS converter to read true RMS for any waveform
shape.
Averaging Type
– A voltmeter that requires a sine wave waveform shape to provide an
accurate reading.
Effi ciency
– Usually given as a percentage, ef
fi
ciency is the ratio of the output to the input. The
ef
fi
ciency changes with power output levels of any inverter.
Electrolyte
– Typically a mixture of water and sulfuric acid that is used in lead-acid batteries; it
is commonly referred to as battery acid.
Equalization
– Controlled “overcharging” of the battery causing it to bubble and mix. This helps
reduce strati
fi
cation.
Float Stage
– During the third stage of three stage charging, the voltage and current are reduced
to a level that will trickle charge or maintenance charge the battery. This assures the battery
remains fully charged even while sitting.
Fuse or Disconnect
– When current exceeds a preset limit the fuse or disconnect will fail before
the wiring or equipment it is protecting. Disconnects are also called circuit breakers. These are
usually reset and can act as a switch to turn off power to equipment for servicing.
Grid Power (The grid)
– Also called utility power, this refers to the public power distribution
system.
Impedance
– Slows the electrical
fl
ow of Alternating Current (AC).
LED (Light Emitting Diode)
– A light or indicator made up of semi-conducting material.
