How to Service Cell Phone Batteries

With the move to lithium-ion, fewer cell phone batteries fail during the warranty period than with nickel-based chemistries. Lithium-ion is less temperamental and needs less customer preparation than nickel. Yet, the volume of returned batteries remains relatively high.

A North American cellular provider with about 12 million subscribers receives roughly 70,000 warranty returns per month. Out of these returned handsets, 50% have mechanical failures; 30% are performance related issues; 15% have battery or charger related problems; and 5% have miscellaneous faults.

There are many reasons for the battery failures. The battery may not have been properly charged before use. Perhaps the packs remained on the shelf too long or the charger is not functioning correctly. Lack of battery understanding may also be to blame. The true reason may never be known.

To satisfy the customer and honor warranty obligations, the stores provide a replacement battery, no questions asked. Competition makes it tough to do otherwise. The faulty batteries are then returned to the manufacturer for replacement.
Phone manufacturers are aware that 80-90% of the returned batteries have either no problem or can easily be restored with a battery analyzer. The remaining 10-20% can often be revived by reactivating the safety circuit with a boot program and by applying charge/discharge cycles. Only a small percentage of batteries returned under warranty exhibit non-correctable faults.

Not all batteries and handsets brought in for service fail due to manufacturer's defects. Some batteries get damaged due to dropping and other physical abuse. A Service Manager of a leading cell-phone manufacturer hinted that coffee submersion is a common cause of failure. The acid in the coffee manages to corrode the electrical conductors in the handset and the battery. Coffee submersion occurs when the user accidentally mistakes the cup of coffee with the charger or cradle.

To reduce the flow of warranty goods, some manufacturers began charging $35US for no-fault returns. With the added cost, the dealers had no other option than to continue accepting and replacing returns from fickle customers. Warehouses started to fill with dead merchandise; and in 1997 a critical mass was reached. The cost of exchange, lost time by retail staff, shipping, warehousing and paying a subsidy for a replacement phone became a multi-million dollar problem.

Refurbishing, a cost-effective exercise

In an effort to salvage returned batteries, some mobile phone manufacturers segregate battery packs according to purchase date. Packs returned within the thirty-day warranty period are marked type 'B'. The batteries are then consolidated and sent to a regional service center where they are serviced. Batteries that are clean, (have no coffee residue) and regain a capacity of 80% or higher, are relabeled and sold at a discount price. The refurbishing program reclaims over 90% of the returned batteries.

On the strength of the success, some battery-refurbishing houses have extended the service to include batteries that are up to one year old. Repairing these older packs yields a 40-70% restoration rate. Managers have indicated that effectively run battery refurbishing centers manage to generate a profit. Equally importantly is the environmental benefit in restoring rather than disposing of a battery.

Storefront battery service

Servicing a batteries at point-of-sale is becoming a viable alternative to sending the pack to central service centers. With storefront service, the pack goes no further than to the store that sold the product. The batteries are tested, repackaged, and made ready for the next customer with a battery problem. This eliminates courier charges and relieves the warranty obligation by the manufacturers.

Modern battery analyzers are equipped with rapid-test programs that assess the battery state-of-health in a few minutes. Some analyzers (Cadex) offer a boost program to wake up seemingly dead batteries because regular chargers can no longer recharge these packs. The service takes only a few minutes.

How does a battery fall asleep? A lithium-ion may become dysfunctional if discharged too deeply without applying a recharge after use. The boost program applies a gentle charge current to reactivate the battery's safety circuit. A fast-charge follows. To demonstrate the effectiveness of boost, 27 of 92 returned lithium-ion batteries were permanently restored with the boost function of a battery analyzer (Cadex C7400) at the Cadex test laboratory.

If a pack requires a complete service of priming and reconditioning, the customer is asked to come back later. Alternatively, a refurbished battery can be given as a replacement. Only batteries with mechanical defects or those with non-correctable electrical problems need replacement.

Connecting the battery to the analyzer has been a major challenge for customer service staff. Setting the correct battery parameters and selecting a program is another hurdle. If a store handles a limited number of phones or if trained staff is not available, custom battery adapters are the answer. Custom adapters are made for a specific battery type and allow easy insertion of the battery. A wrong connection is not possible. Because of the firm contact provided between battery and analyzer, the custom adapters produce the most accurate readings, especially on rapid-testing. (Cadex offers the SnapLock custom adapters that automatically configure the analyzer to the correct setting.)

Service technicians dealing with a multitude of batteries may prefer a universal battery adapter. This requires programming the battery analyzer to the correct battery chemistry, voltage and milliampere rating. Once set, these parameters can be stored in those adapters equipped with a memory chip. (The Cadex adapters hold up to 10 battery configuration codes. If more storage is needed, a PC with BatteryShop™ software will be required. With a PC, the user can program the analyzer by clicking the mouse on the selected battery.)

Why was storefront service not done earlier?

Point-of-sale service has only become feasible with modern, easy-to-use battery analyzers. Older units were designed for trained technicians and engineers. The programs consisted of cycling to remove the 'memory' on nickel-based batteries. Lithium-ion no longer suffers from memory and cycling has little effect in improving this battery chemistry.
Today, customers want fast service and are not prepared to wait for long service procedures. Neither can the equipment be tied up for any length of time. One of the key features of the modern battery analyzer is the ability to assess the battery quickly and apply the needed repairs in minutes rather than hours.

Offering battery test service at storefronts improves customer service and enhances overall customer satisfaction. Organizations using modern battery analyzers have reported sharp reductions in service related expenses. Manufacturers support storefront service and often furnish the participating dealers with battery analyzers of choice. This trend is growing. With camera phones and increasing use of data transmissions, the battery is becoming a critical part in the overall performance of a cell phone.