What are the causes of auxiliary battery failure in cars?
3 Answers
Possible causes of auxiliary battery failure in cars include: damage to the auxiliary battery fuse; damage to the auxiliary battery itself; malfunction of the generator or charging system; or faults in related wiring harnesses. Additional information is as follows: 1. Solution: When a Mercedes-Benz auxiliary battery fails, it requires repair at a 4S shop and cannot be resolved automatically. Failure of the auxiliary battery indicates an issue with the vehicle's engine battery, which should not be taken lightly. Once the auxiliary battery fails, many functions may become inoperative, such as auto start-stop, reverse radar, seat heating, HOLD function, etc. 2. Impact: Auxiliary battery failure can lead to slow car startup, issues with certain circuit controls, or insufficient power. It may also cause the car battery pack voltage to drop too low, potentially leading to other faults. Therefore, timely repair and replacement at an automotive service center are necessary.
Last time my car showed an auxiliary battery fault, it took me quite a while to figure it out. The auxiliary battery mainly powers devices like auto start-stop and entertainment systems, which is different from the main battery's purpose. Common faults include battery aging, especially in vehicles with frequent start-stop usage - they're usually depleted in three to four years. Problems with the charging system are also a potential hazard; if the alternator doesn't charge the auxiliary battery, it will quickly lose power. Erratic instrument readings or malfunctioning start-stop functions are absolutely the first warning signs! Before attempting any repairs, remember never to tamper with the 48V circuit in hybrid vehicles - the dealership technician told me improper handling could easily burn out the controller, which ended up costing me nearly two thousand yuan to fix.
I once encountered an issue with the auxiliary battery throwing a fault code. Suddenly, the dashboard displayed a warning icon, and the start-stop function stopped working completely. After inspection, it turned out to be a false alarm by the control unit due to voltage fluctuations—simply clearing the code fixed it. Auxiliary batteries are particularly vulnerable to low temperatures; during this year's cold wave, many car owners reported significant battery capacity shrinkage. These small batteries don't have much capacity to begin with. If you keep the AC or music on after turning off the engine, they can be drained in just half an hour. A reminder to everyone: if a red battery symbol pops up on the central display, don't rush to restart. Try charging it first. A mechanic taught me a simple yet effective trick—remove the left trim panel in the trunk and use a multimeter to check if the voltage drops below 12V.
