ChinaCALB, China’s third-largest battery maker, announced a manufacturing quality overhaul on August 6 in response to a wave of cell failures in GAC Aion S Plus, Aion S Charming 580, and Aion S Max sedans built between 2022 and 2023 that surfaced publicly in July. Owners reported cells swelling into a curved shape - the failures became known online as “banana batteries” - along with reduced range, battery-management-system warnings, insulation faults, electrolyte leakage, and sudden power loss while driving. CALB says a 177 Ah LFP cell is behind the defect, with a 4.7% fault-detection rate across roughly 213,000 affected vehicles in China, concentrated in cars run hard commercially and put through 150,000 to 300,000 km. A Xinhua investigation brought the issue into public view before either company responded.
Neither CALB nor GAC Aion has issued a formal recall. Instead, both companies apologized and published a remediation plan on July 18: GAC Aion extended the battery warranty on affected models to 8 years or 300,000 km, offering free inspections and replacements plus a subsidy for owners whose repair takes more than five days, while CALB opened a direct maintenance channel and pledged to take responsibility for cell quality. A warranty extension addresses owners of cars already on the road without the regulatory process, cost disclosure, and public notice that a recall requires.
CALB’s overhaul covers more than the factory floor. The company says it has tightened manufacturing tolerances on its production lines, but it has also restructured how failures get traced and validated internally, given its quality team new authority, and changed how it handles customer complaints - changes aimed at catching the next defect before it reaches 150,000 km on customers’ cars, not just this one. CALB has said the measures will raise near-term costs and weigh on profits.
The episode underlines how much of an EV’s reliability now sits with its battery supplier rather than the automaker whose badge is on the car. GAC Aion sources cells from multiple suppliers, and this dispute names CALB specifically rather than the brand’s batteries as a whole.
The Aion S Plus is GAC Aion's compact electric sedan, sold in China and exported as the Aion ES. A 55.6 kWh LFP battery gives 505 km of CLTC range from a single 134 hp front motor, with China prices from ¥89,800.
