CAPACITY OF A BATTERY

Radio Record, Volume I, Issue 47, 8 June 1928, Page 3

CAPACITY OF A BATTERY

HOW TO ESTIMATE IT. The capacity of a wet battery has nothing whatever to do with "capacity" in the sense that we use the term applied to condensers. What is meant is the accumulator’s capacity. to give up a certain amount of electricity. An accumulator is designed to produce a certain current, and this is reckoned in amperes; and it will give this current for a certain time, which is reckoned in hours. The product of these two factors is called the "am-pere’-hour capacity" of that accumulaor. . For instance, if the actual capacity. of an accumulator is 40 ampere hours, it means that this accumulator will give 1 ampere of current for 40 hours, Similarly it would give half an ampere for approximately 80 hours, or it would give 2 amperes for 20 hours, before recharging beecame necessary. * So we see that the ampere-hour eapacity of an accumulator can be regarded as a convenient method of finding how long it would last if it gives a certain current, or converse:y how many hours it will take to discharge it, if the discharge is at a certain rate. A good idea of the number of hours an accumulator will last without recharging can be obtained merely by adding together the current consumption of all the valves in the set; then divide this figure into the actual am-pere-hour capacity of the accumulator and the answer will be the number of hours that it will last (approximately). It is important to note that this applies to the actual ampere-hour eapacity of the accumulator and not to the "ignition" rating, which is generally about twice that of the actual }ampere-hour capacity,