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.