The most common battery rating is theAMP-HOUR RATING. This is a unit of measurement for battery capacity, obtainedby multiplying a current flow in amperes by the time in hours of discharge.(Example: A battery which delivers 5 amperes for 20 hours delivers 5 amperestimes 20 hours, or 100 ampere-hours.)
Manufacturers use different dischargeperiods to yield an different Amp-Hr. Rating for the same capacity batteries,therefore, the Amp-Hr. Rating has little significance unless qualified by thenumber of hours the battery is discharged. For this reason Amp-Hour Ratings areonly a general method of evaluating a battery's capacity for selectionpurposes. The quality of internal components and technical construction withinthe battery will generate different desired characteristics without effectingits Amp-Hour Rating. For instance, there are 150 Amp-Hour batteries that willnot support an electrical load overnight and if called upon to do sorepetitively, will fail early in their life. Conversely, there are 150 Amp-Hourbatteries that will operate an electrical load for several days before needingrecharging and will do so for years. The following ratings must be examined inorder to evaluate and select the proper battery for a specific application:COLD CRANKING AMPERAGE and RESERVE CAPACITY are ratings used by the industry tosimplify battery selection.