Lamar Technologies Alpha C-25 - Manual (Page 20)

APPENDIX A – BATTERY OVERVIEW
ALPHA C-25 Manual V2.1.doc Page 20
APPENDIX
APPENDIX A - BATTERY OVERVIEW
CLASSES OF BATTERIES
Batteries can be divided into two major classes: primary and secondary. The primary
batteries are not practically reusable once its useful energy has been discharged. The
secondary battery is rechargeable. In the following only secondary batteries will be
covered.
SECONDARY BATTERIES
Secondary batteries differ from primary batteries in that they may be recharged. Some
of the materials in the cells of primary batteries are usually consumed in the process of
changing chemical energy into electrical energy. In the secondary system, the materials
are transferred from one electrode to the other as the cells discharge. The cells are
restored to their original state of charge by forcing an electric current through the cells in
a direction opposite to that of the discharge. These batteries are used in a multitude of
applications ranging from megawatt sizes in submarines to milliwatt sizes in portable
radios.
LEAD-ACID BATTERIES, VENTED OR VRLA
The lead-acid battery is a rechargeable system using acid electrolyte
(sulfuric acid and water). Lead-acid batteries may be vented or sealed.
The advantages of lead-acid batteries are that they have a low initial
cost, require low maintenance, and their discard cost is low. The VRLA
batteries, on a per-weight basis, provides as much power as a nickel-
cadmium battery. Vented Lead-acid batteries shed active material from
the positive plate, proportional to the number of charge/discharge
cycles. For Vented lead-acid batteries this results in diminishing battery
performance with age and loss of active material on the positive plates
due to the washing action of the gas bubbles generated during charge.
The open circuit voltage of a fully charged cell is about 2.15-2.20 volts.
The discharge voltage is about 2.0 volts and varies with temperature,
discharge rate, charge state, and age. The VRLA batteries are
normally charged in the CP mode.
The lead-acid battery is the most widely used of the secondary battery types. Major
applications include automobiles, aircraft, aircraft support equipment, and various
industrial applications.