Figure 22.
Correction chart.
14. BATTERY RATINGS.
a. The amount of water a can will hold may be measured in pints, quarts, or
gallons. Battery capacity is measured in ampere-hours which are the number of
amperes the battery will deliver multiplied. by the number of hours the battery
will deliver it. For example, suppose a battery will deliver 5 amperes for 20
hours, then 5 amperes multiplied by 20 hours equals 100 ampere-hours. If the
ampere-hour rating is based on nothing more, the rating would change if the rate of
discharge is changed. Suppose that we increase the load on the battery from 5 to
10 amperes. The battery would then produce the 10 amperes for a period less than
10 hours, so its rating would figure to be less than 100 ampere-hours. As you can
see, some form of standard procedures must be used to rate the ampere-hours before
the ratings will mean the same in all tests.
b. The capacity of batteries is rated
by a standard procedure called the
20-hour rating. This rating gives the number
of ampere-hours the battery will
deliver if it is discharged at a uniform rate
for 20 hours, at a temperature of
80, and with a battery voltage of 1.75 volts
per cell at the end of the 20-hour
period.
OS 010, 3-P27
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