When charging a battery, the ready light will eventually illuminate, indicating that the battery is fully charged.  The user assumes that the battery has reached its full potential and the battery is taken in confidence. 
In no way does 'green light' guarantee sufficient battery capacity or assure state-of-health.  Similar to a toaster that pops up the bread when brown, the charger fills the battery with energy and 'pops' it to ready when full.  Charge termination is commonly detected by a rise in battery temperature. 

The rechargeable battery is a corrosive device that gradually loses its ability to hold charge as part of natural aging.  Many users are oblivious to the fact that their batteries barely last a day with no reserve energy to spare.  In fact, weak batteries can hide comfortably because little demand is placed on them on a routine day.  The situation changes when full performance is required during an emergency.  Total collapse of portable systems is common and such breakdowns are frequently related to poor battery performance. 

Carrying larger batteries or switching to higher energy-dense systems does not assure better reliability if the weak batteries are not "weeded" out. 

Likewise, the benefit of using advanced ultra-high capacity systems offers little advantage if the packs are allowed to dwell in the fleet after their prime. 

Figure 2 illustrates four batteries with different ratings and state-of-health conditions.  Batteries B, C, and D show reduced charge acceptance because of memory problems and other deficiencies.  The worst pack is Battery D; it switches to ready after only 14 minutes of charge (assumed time). 
 

This battery is a likely candidate to be picked when a fresh battery is required in a hurry.  Unfortunately, this pack will last only for a brief moment.  Battery A, on the other hand, has the highest capacity and takes the longest to charge. 

Ironically, battery A is least likely picked because it is slowest to charge. 

The weak batteries are charged quicker and remain on "ready" longer than the good batteries.  The bad tend to gravitate to the top, making them available for the unsuspecting user.  In an emergency situation that requires quick charge action, the batteries that are on ready may be 'deadwood'. 

The reliability of portable equipment is as good as the battery.  While most equipment receive scheduled maintenance and calibration, batteries get little support.  Historically, batteries are serviced either when they no longer hold charge or when the equipment is sent in for repair.  As a result, battery-operated devices become unreliable with time. 

Implementing a battery maintenance plan demands effort and commitment on behalf of management. Battery maintenance must become an integral component of an organization's overall maintenance and repair activities. 

Whether the batteries are done in-house with their own battery analyzers, or sent to an independent firm specializing in that service, sufficient spare batteries must be kept on hand to replace those temporarily taken away from service. 

Never indiscriminately remove batteries without assuring proper replacement. After service, the batteries are marked to identify performance and service dates.  This is best done by attaching a battery label.  With the basic battery information shown, a user removing a battery from the charger will look for a good capacity reading and valid date.

Battery analyzers are now available that automatically print a label with date, name of organization from the unit.  A sample of such a label is illustrated in figure 3. 

Several methods are available to maintain a fleet of batteries.  A simple, self-governing system is illustrated in figures 4 to 6. 

Only 30 minutes per day should be required by a technician to maintain the system.  The equipment needed is one or several battery analyzers capable of producing battery labels. 

After servicing, the restored batteries are returned to the charger; those that failed are replaced with new ones. 

Result, battery maintenance assures that all packs at the user level perform at the expected capacity level. 

When taking a battery from the charger, the user checks the service date on the battery label.  If expired, the battery is placed into the box marked "To be serviced".  Periodically, the box is removed and the batteries are serviced and re-certified with a battery analyzer. 

Battery maintenance has been simplified with the introduction of battery analyzers which offer target capacity selection.  This novel feature works on the must meet a user-defined perform test or target capacity.  Nickel-based batteries that fall short of the required capacity are automatically restored with the analyzer's recondition cycle.  Batteries that fail to recover are subsequently replaced with new packs. 
Recondition consists of a discharge to one volt per cell, followed by a secondary discharge to 0.4V at a much-reduced current. 

While removing the remaining energy, the molecular structure of the cell is reset to its original chemical composition and the cell is rebuilt.  This process commonly restores nickel-based batteries to full service. 

On recondition, the battery is first discharged to one volt per cell after which the discharge continues at a much-reduced current. 

It should be mentioned, however, that batteries with high self-discharge and those containing shorted cells cannot be corrected with recondition; neither can a battery that is worn out due to old age or one that has been damaged through abuse. 

A practical target capacity setting for most battery applications is 80percent.  Increasing the capacity to 90 percent will, in essence, raise the performance level by 10 points. 

It should be noted that higher settings will yield fewer batteries because older batteries often cannot reach 90percent capacity. 

The target capacity setting of a battery analyzer can be compared to a student entry-exam for college. 

With a passing mark of 80 percent, a reasonable number of students will pass. If the passing mark is set to 90 percent, fewer but higher qualified students will be admitted. 
After service, the batteries are relabeled and returned to the charger.  Those batteries which fail to meet the target capacity are replaced with new packs.  All batteries in the charger are now certified to meet a required performance standard. 

Public Safety: Organizations tend to postpone battery maintenance until a crisis situation develops.  A story comes to mind where a fire brigade using portable radios experienced chronic communication problems, especially during calls lasting longer than two hours. The symptom manifested itself in their radios not transmitting, although receive worked fine. This situation left the fire fighters in an awkward position because they were unaware that their call did not get out. 

The fire brigade acquired a Cadex battery analyzer and all batteries were serviced through exercise and recondition methods to restore lost capacity.  Those batteries that did not recover to a preset target capacity were replaced. 

Shortly thereafter, the fire brigade was 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 day, the captain of the fire brigade personally contacted the manufacturer of the battery analyzer and enthusiastically extended his congratulations for the superb performance of the device. 

Emergency preparedness: Batteries placed on prolonged standby commonly fail when put to use.  Such was the case when a Cadex Representative was allowed to view a State Emergency Management Facility of a large US city.  In the fortified bunker, over one thousand batteries where kept in chargers.  The green lights glowed, indicating that the batteries where ready at a moments notice. 

The officer in charge stood erect and in an assured voice said "We are prepared for any emergency". 

The salesman then asked to check it's state-of-health.  Within seconds, the analyzer detected a fail condition.  In an effort to good, the officer handed another battery from the charger bank, only to find out that is also failed. 

Scenarios such as these are quite common.  The disturbing fact is that little is done to correct the system, once discovered. 

Commonly, extra charge current is not available.  All the officer can do is pray that an emergency will not occur. 

Military:  Another user group that relies heavily batteries is the military.  Defense organizations take pride in using the highest quality and best performance equipment. 

When it comes to batteries, however, there is an apparent lack of discipline and maintenance is frequently ignored. 

The battery often escapes the scrutiny of a full military inspection and only the visual appearance is checked.  Little effort is made in keeping track of cycle count, user pattern, and age. 

Eventually, weak batteries get mixed in with the new ones and the system becomes unreliable.  In some cases, the batteries soldiers carry might as well be rocks. 

Without a system to systematically remove weak batteries, the benefit of the state-of-the-art, ultra-high capacity battery is defeated.  The soldiers carry rocks instead of batteries. 

Today's market offers a wide selection of battery analyzers at various prices.  There are two basic types of systems available, namely fixed current and programmable units. 

Programmable units are more accurate, easier to adapt to different battery types and more effective in restoring weak batteries than fixed current analyzers.  The results are higher battery recovery, reduced operator time, increased throughput, simpler operation and the use of less trained technicians. 

An advanced battery analyzer, such as the Cadex C7000, evaluates the condition of each battery and implements the appropriate service to restore its performance.  A recondition cycle is applied if a user-selected capacity level cannot be reached. 

The battery settings are stored in interchangeable battery adapters that configure the analyzer to the correct function when installed. 

Service programs address the different battery needs and include: Ohm Test to measure the battery's internal resistance; Prime to prepare a new battery for field use and Auto to recondition a weak battery. 

In addition, Custom programs allow the user to create specialized programs such as self-discharge test and life cycling. 
Analyzers capable of printing service reports and battery labels simplify battery maintenance and help in the scheduling of battery service. 

To manage a large battery fleet, battery analyzers should be capable of interfacing to a PC. BatteryShop by Cadex Electronics is software that simplifies battery maintenance in a market that offers an ever-increasing number of battery types. 

With BatteryShop, the user simply enters the battery model number and the software automatically sets the correct parameters in the analyzer. Battery manufacturer, vendor references, price, purchase date and performance history of all batteries are stored in a database and made available for cost analysis and performance verifications.