Technical Manual

Document No. 6-0101 Rev. F Page 28 of 40
Current -
The rate of flow of electricity. The movement of electrons along a
conductor. It is comparable to the flow of a stream of water. The
unit of measurement is an ampere.
Cut Off Voltage -
Battery voltage reached at the termination of a discharge. Also
known as end point voltage or EPV.
Cycle -
One sequence of discharge and charge.
Cycle Life -
The total number of charge/discharge cycles before the battery
reaches end of life (generally 80% of rated capacity).
Deep Discharge -
Withdrawal of more than 80% of the rated capacity.
Depth Of Discharge -
The portion of the capacity taken out during a discharge,
expressed as a percent of rated capacity.
Discharge -
The conversion of the chemical energy of a cell or battery into
electrical energy and withdrawal of the electrical energy into a
load.
End Of Life -
The stage at which the battery fails to deliver acceptable capacity
(typically 80% of nameplate rating).
Float charge -
A method of maintaining a battery in a charged condition by
continuous, long
term, constant voltage charging at level sufficient
to balance self-discharge.
Gassing -
The evolution of gas from one or more of the electrode plates in a
cell. Gassing commonly results from local action (self discharge)
or from the electrolysis of water in the electrolyte during charging.
Internal Impedance -
Same as Internal Resistance.
Internal Resistance -
The opposition or resistance to the flow of a direct electric current
within a cell or battery; the sum of the ionic and electronic
resistance of the cell components. Its value varies with the
current, state of
charge, temperature, and age. With an extremely
heavy load, such as an engine starter, the cell voltage may drop
significantly. This voltage drop is due to the internal resistance of
the cell. A cell that is partly discharged has a higher internal
resistance than a fully charged cell, hence it will have a greater
voltage drop under the same load. This change in internal
resistance is due to the accumulation of lead sulfate in the plates.
Open Circuit Voltage -
The voltage of a battery when it is not delivering or receiving
power, and has been at rest long enough to reach a steady state
(normally, at least 4 hours).
Overcharge -
The forcing of current through a cell after all the active material
has been converted to the charged state. In other words, charging
continued after 100% state of charge is achieved. The result will
be the decomposition of water in the el
ectrolyte into hydrogen and
oxygen gas, heat generation, and corrosion of the positive
electrode.
Self Discharge -
The decrease in the state of charge of a cell or a battery, over a
period of time, due to internal electrochemical losses.
Series Connection -
Voltage of the system is cumulative. Capacity stays the same.
Shelf Life -
The period of time (measured from date of manufacture) at a
specified storage temperature after which the cell or battery
needs
to be boost charged so it does not suffer permanent capacity loss.
State Of Charge (SOC) -
The available ampere hours in a battery at any given time relative
to its full charge capacity.
State Of Health (SOH) -
The available ampere hours in a battery when fully charged
relative to its rated capacity.
Sulfation -
Refers to the formation of hard lead sulfate crystals in the plates
that are difficult, if not impossible, to reconvert to active material.
Temperature, Ambient -
The average temperature of the battery's surroundings.