Ensuring that batteries are running at full capacity and up to the job should be part of all maintenance programs
When a battery is charging, the green “ready” light will indicate that the battery is fully charged. When this happens, the user assumes the battery has reached its full potential and takes the pack with confidence.
The green light does not guarantee a good battery, and it does not assure sufficient runtime. Ready indicates only that the battery is fully charged in whatever space was available to fill. In fact, weak batteries charge more quickly (because there is less to fill) and remain on ready longer than do strong packs. Bad batteries tend to gravitate to the top of the fleet and become a target for the unsuspecting user. Batteries that go ready first may be deadwood.
A weak battery can be compared to the fuel tank of a car that has been filled with rocks. Refueling is quick because the tank holds little fuel. The fuel gauge on the dashboard shows FULL, and everything appears normal except for the distance traveled.
The rechargeable battery is a corrosive device that gradually loses the ability to hold a charge. In the first year, a battery-operated system works well because the batteries are fresh. During the second year, some batteries start losing capacity, and their reliability begins to decline. New packs are added, and in time the battery fleet becomes a jumble of good and failing batteries. That’s when the battery headaches begin. The figure illustrates an aged battery with the so-called “rock content”.
Ensuring Full Capacity
How are the batteries checked? The answer is battery maintenance, commonly done with a battery analyzer. While organizations such as those for public safety have been using battery analyzers for many years to restore and prolong nickel-based batteries for two-way radios, analyzers are now making their way into servicing batteries for laptops, handheld scanners, and medical and other industrial devices.
Fleet batteries should be serviced once every 2 months. Attaching a small battery label containing service date, due date, capacity reading, and internal battery resistance keeps track of the serviced batteries. This system is self-governing because the user picks only a battery that has properly been serviced and labeled.
As part of the maintenance program, expired batteries are segregated and serviced on a battery analyzer. Packs that regain full capacity are relabeled and returned to the field; those that fall below the set target capacity are replaced with new packs. Modern battery analyzers enable nontechnical staff to service a battery fleet in less than 30 minutes per day.
Does battery maintenance prolong battery life? Yes. The life of nickel-based batteries can typically be doubled with scheduled service. For lithium-ion batteries, the purpose of maintenance leans toward verifying performance rather than toward restoring weak packs and extending life. Regular maintenance reduces unexpected downtime caused by aging batteries. Lithium-ion batteries provide a service life of 2 to 3 years and deteriorate even when not in use. Cool temperature reverses the aging process.
Summary
Charging alone does not assure reliable batteries. Some quality control is required to keep a battery fleet healthy. Battery maintenance not only prolongs the life of nickel-based batteries, it also weeds out deadwood. Such deadwood can be identified relatively easily because batteries do not die suddenly but get weaker over time.
Problems with weak batteries are most apparent in emergencies and in heavy traffic when full performance is needed. Battery failure during such critical moments is not an option. To strengthen the battery fleet, organizations are beginning to take a proactive approach in terms of battery maintenance and record keeping. The cost savings are apparent. Longer battery life and fewer units that need repair are the direct result.
Isidor Buchmann is the founder and CEO of Cadex Electronics Inc, Vancouver, BC. He has a background in radio communications and has studied the behavior of rechargeable batteries in practical, everyday applications for 2 decades.
