BATTERY ANALYZERS FOR CRITICAL MISSIONS


Every so often, a call is received from a customer who is concerned that their battery analyzer developed a fault because it no longer indicates correct capacity readings. In most cases, the customer had just purchased a set of new batteries and when tested with the analyzer, the reading came up to only half the expected capacity. "Naturally, if two or more of these brand new batteries show such low readings, it must be the analyzerís fault" is their comment.

Conventional wisdom says that a new battery always performs flawlessly, yet many users have learned that a battery fresh from its shrink wrap may not always meet the manufacturer's specifications. With a battery analyzer, non-performing batteries can be identified, primed and, if the capacity does not improve, returned to the vendor for warranty replacement. In fact, whole shipments of new batteries have been returned because of poor performance with that batch. Had these batteries been released into the field without prior inspection, the whole system would have been affected, resulting in unpredictable performance and frequent down time.

A battery analyzer also performs the important function of weeding out the deadwood in a battery fleet. Since it only takes one bad battery to render a system unreliable, the userís inability to determine which battery is faulty presents a major problem. Bad batteries tend to gravitate to the top and are picked more often than good ones. Here is the reason why:

The non-performers are charged quicker than the good batteries because they have a lower charge acceptance. As a result, these weak batteries remain on "ready" longer, making them available to be chosen by the unsuspecting user. Although fully charged, they may hold less than half the normal capacity. Similar to a fuel tank that is filled with crushed rock, the amount of fuel it can hold is less than a clean tank, even though the tank is full. In an emergency situation which requires quick charge action, the only batteries that are on ready may be those that are deadwood. With lives at stake, such a situation can have grave consequences.

A story comes to mind where a public safety organization experienced chronic radio communication problems, especially during critical missions. The symptom manifested itself when their portable radios were not being able to transmit after two hours of use, but the receive function worked fine. The organization acquired a Cadex battery analyzer and all batteries were serviced through exercise and recondition methods. Those batteries that did not recover to a preset target capacity were replaced. Shortly thereafter, the safety officers were summoned to a ten-hour call that demanded heavy radio traffic. To their astonishment, none of the portable radios failed. The success of this flawless operation was credited to the excellent performance of their batteries. The following morning, the head of the safety organization personally contacted Cadex Electronics and enthusiastically endorsed the use of the battery analyzer.

The tedious task of keeping a battery fleet at an acceptable capacity level has been simplified with the introduction of battery analyzers that offer target capacity selection. This novel feature works on the basis that all batteries must pass a user-defined performance test. Batteries that fall short are restored with the recondition cycle and if they fail to recover, are subsequently replaced.

The target capacity setting of a battery analyzer can be compared to a student entry-exam for college. Assuming that the passing mark is 80 percent, the students that do not obtain that level are given the opportunity to take a refresher course and are thereafter permitted to rewrite the exam. In our analogy, the refresher course is the recondition cycle. If the passing mark is set to 90%, for example, fewer but higher qualified students are admitted.

A practical target capacity setting for batteries in public safety, for example, is 80%. Increasing the capacity requirement to 90% will, in essence, provide an extra 10 percentage points of available energy. However, it should be noted that higher settings will yield fewer batteries since more will fail as they age.

Some battery analyzers display both the reserve capacity (motor fuel left in the tank before refill) and the full-charge capacity (full tank) of the batteries serviced. With this information on hand, the user is able to calculate how much energy was consumed during the day by subtracting the reserve from the full-charge capacity. To ensure a reasonable safety margin, the reserve capacity, after a routine day, should be about 20 percent. If less reserve capacity is available, the minimum capacity threshold should be increased by setting the target capacity higher. By allowing reasonable reserve capacity, unexpected downtime in an emergency or on extra-strenuous field activities can virtually be eliminated.

To get the most out of a battery, many organizations have set up a two-tier system that allocates the top performing batteries for critical applications and assigns the lower performers for lighter duties. Such a system makes full use of the available resources without affecting reliability.

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