Appendix C Definitions of Terms

DOE-SPEC-3018-96

APPENDIX C

DEFINITIONS OF TERMS

Aging Factor

A factor used to ensure that a battery will meet its duty cycle

requirement upon initial installation and at its end-of-life. It is common

for batteries to deliver 90 to 95% of rated capacity upon delivery.

Capacity eventually rises to 100%, stabilizes there for a period of time,

then starts to decrease to 80%. Capacity drops rapidly after reaching

80%, so 80% is assumed to be the point at which the battery should be

replaced. The aging factor used would then be 1.25 (1/80%).

Battery

Two or more cells electrically connected to form a unit. Under common

usage, the term also applies to a single cell.

Cutoff Voltage

Cell or battery voltage at which the discharge is terminated. The cutoff

voltage is specified by the manufacturer and is a function of discharge

rate and temperature. (Also called end-of-duty cycle voltage.)

Design Margin Factor

Used to compensate for spare or excess capacity for future loads.

(kd)

The design margin factor can be assumed to be 1.0 for UPS

applications where the battery system is sized for full capacity of the

inverter. For general-purpose applications, the design margin factor

can range from 1.10 to 1.25.

Duty Cycle

The load currents a battery is expected to supply for a specified time

period.

End-of-Duty Cycle

See "Cutoff Voltage."

Equalizing Charge

Charge applied to a battery which is greater than the normal float

charge which is used to completely restore the active materials in the

cell, bringing the cell float voltage and the specific gravity of the

individual cells back to "equal" values.

Float Charge

Method of charging in which a secondary cell is continuously

connected to a constant-voltage supply that maintains the cell in a

fully-charged condition.

Flooded-Type Lead-Acid

Two or more cells electrically connected for producing electric

Battery

energy through a chemical reaction whose electrolyte is a liquid. A

flooded-type lead-acid battery is housed in a transparent jar so that the

internal plate structure can be viewed to ascertain the condition of the

battery. The flooded lead-acid battery is also equipped with openings

for the addition of water (which is evaporated and electrolyzed into

gases) and explosionproof vents to reduce the hazard of accumulating

hydrogen and oxygen within the cell from an external ignition source

such as an electric spark or cigarette lighter.

Gel Cell

The gel cell uses a silica added to the electrolyte to form a gel which

liquifies above some fixed stress level, and converts back into a gel

when left standing. Only the electrolyte between and around the plates

C-1