|
Battery Analyzers for Critical Missions
Occasionally, a customer will call Cadex because
their battery analyzer appears faulty. The complaint: the
battery no longer indicates correct capacity readings. In
most cases, the customer has just purchased new batteries.
When testing these new packs, the capacities read 50 to 70 percent.
The customer assumes that, “Naturally, if two or more of these
brand new batteries show low readings, it can only be the
analyzer’s fault.”
Battery analyzers play a critical role in identifying
non-performing batteries, new or old. Conventional wisdom
says that a new battery always performs flawlessly. Yet many
users realize that a fresh battery may not always meet the
manufacturer's specifications. Weak batteries can be identified
and primed. If the capacity does not improve, the packs can
often be returned to the vendor for warranty replacement.
Whole batches of new batteries have been sent back because
of unacceptable performance. Had these batteries been released
without prior inspection, the whole system would have been
jeopardized, resulting in unpredictable performance and frequent
down time.
In addition to getting new batteries field-ready,
battery analyzers perform the important function of weeding
out the deadwood in a battery fleet. Weak batteries can often
hide among their peers. However, when the system is put to
the test in an emergency, these non-performers become a real
nuisance.
Organizations tend to postpone battery maintenance
until a crisis situation develops. One fire brigade using
two-way radios experienced chronic communication problems,
especially during emergency calls which lasted longer than
two hours. Although their radios functioned in the receive
mode, they were not able to transmit and firefighters were
left unaware that their calls did not get through.
The fire brigade 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 firefighters were summoned
to a ten-hour call that demanded heavy radio traffic. To their
astonishment, none of the two-way 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 endorsed the use of
the device.
Batteries placed on prolonged standby commonly
fail. Such was the case when a Cadex representative was allowed
to view the State Emergency Management Facility of a large
US city. In the fortified underground bunker, over one thousand
batteries were kept in chargers. The green lights glowed,
indicating that the batteries where ready at a moment’s notice.
The officer in charge stood tall and confidently said, “We
are prepared for any emergency”.
The representative then asked the officer to
hand over a battery from the charger to check the state-of-health
(SoH). Within seconds, the battery analyzer detected a fail
condition. In an effort to make good, the officer grabbed
another battery from the charger bank but, it failed too.
Subsequent batteries tested also failed.
Scenarios such as these are common but such flaws
do not get rectified quickly. Political hurdles and lack of
funding are often to blame. In the meantime, all the officer
can do is pray that no emergency occurs.
Eventually, a new set of batteries is installed
and the system returns to full operational readiness. However,
the same scenario will reoccur, unless a program is implemented
to exercise the batteries on a regular basis. Advanced battery
analyzers, such as the Cadex 7000 Series, apply a conditioning
discharge every 30 days to prevent the memory phenomenon
on nickel-based batteries.
Figure 16-1: Results of neglecting your
battery’s state-of-health.
Maintenance helps keep deadwood
out of your arsenal.
The military also relies heavily on batteries.
Defense organizations take great pride in employing the highest
quality and best performing equipment. When it comes to rechargeable
batteries, however, there are exceptions. The battery often
escapes the scrutiny of a full military inspection and only
its visual appearance is checked. Maintenance requirements
are frequently ignored. Little effort is made in keeping track
of the battery’s state of health, cycle count and age. Eventually,
weak batteries get mixed with new ones and the system becomes
unreliable. This results in soldiers carrying rocks instead
of batteries. A battery analyzer, when used correctly, keeps
deadwood out of the arsenal.
The task of keeping a battery fleet at an acceptable
capacity level has been simplified with 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. If they fail to recover, the packs are 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 who
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 that is applied to nickel-based batteries. If the passing
mark is set to 90 percent, for example, fewer but higher
qualified students are admitted.
A practical target capacity setting for batteries
in public safety is 80 percent. Increasing the capacity
requirement to 90 percent will provide an extra 10 percentage
points of available energy. However, higher settings will
yield fewer batteries since more packs will fail as they age.
Many organizations allocate the top performing
batteries for critical applications and assign the lower performers
for lighter duties. This makes full use of the available resources
without affecting reliability.
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.
The user is then 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 after a routine
day, the reserve capacity should be about 20 percent.
If less reserve capacity is available, the target capacity
should be set higher. By allowing reasonable reserve capacity,
unexpected downtime in an emergency or on extra-strenuous
field activities can be eliminated.
|
