DO You Know Define Battery Life ?

How to define battery life?Most new batteries go through a formatting process during which the capacity gradually increases and reaches optimal performance at 100–200 cycles. After this mid-life point, the capacity gradually begins decreasing and the depth of discharge, operating temperatures and charging method govern the speed of capacity loss. The deeper the batteries are discharged and the warmer the ambient temperature is, the shorter the service life. The effect of temperature on the battery can be compared with a jug of milk, which stays fresh longer when refrigerated.

Most portable batteries deliver between 300 and 500 full discharge/charge cycles. Fleet batteries in portable devices normally work well during the first year; however, the confidence in the portable equipment begins to fade after the second and third year, when some batteries begin to lose capacity. New packs are added and in time the battery fleet becomes a jumble of good and failing batteries. That’s when the headaches begin. Unless date stamps or other quality controls are in place, the user has no way of knowing the history of the battery, much less the performance.

The green light on the charger does not reveal the performance of a battery. The charger simply fills the available space to store energy, and “ready” indicates that the battery is full. With age, the available space gradually decreases and the charge time becomes shorter. This can be compared to filling a jug with water. An empty jug takes longer because it can accept more water than one with rocks. Figure 1 shows the “ready” light that often lies.

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Figure 1: The “ready” light lies

The “ready” light on a charger only reveals that the battery is fully charged; there is no relationship to performance. A faded battery charges faster than
a good one. Bad batteries gravitate to the top.

Courtesy of Cadex

Many battery users are unaware that weak batteries charge faster than good ones. Low performers gravitate to the top and become available by going to “ready” first. They form a disguised trap when unsuspecting users require a fully charged battery in a hurry. This plays havoc in emergency situations when freshly charged batteries are needed. The operators naturally grab batteries that show ready, presuming they carry the full capacity. Poor battery management is the common cause of system failure, especially during emergencies.

Failures are not foreign in our lives and to reduce breakdowns, regulatory authorities have introduced strict maintenance and calibration guidelines for important machinery and instruments. Although the battery can be an integral part of such equipment, it often escapes scrutiny. The battery as power source is seen as a black box, and for some inspectors correct size, weight and color satisfies the requirements. For the users, however, state-of-function stands above regulatory discipline and arguments arise over what’s more important, performance or satisfying a dogmatic mandate.

Ignoring the performance criteria of a battery nullifies the very reason why quality control is put in place. In defense of the quality auditor, batteries are difficult to check, and to this day there are only a few reliable devices that can check batteries with certainty. Read about Difficulties with Battery Testing.