A battery that dies overnight usually means a module or accessory is staying awake after shutdown.
Here’s how to trace a parasitic draw on your CS85 Coupe and what to check first.
Why the battery goes flat overnight
A healthy CS85 Coupe battery should still have enough cranking power after a night parked. If it doesn’t, you’re dealing with a parasitic draw: a module, light, relay, or accessory that keeps pulling current after the car should have gone to sleep. Modern cars with keyless entry, infotainment, and telematics can take 20–40 minutes to fully sleep, so a quick test right after shutdown is misleading. Common culprits include a dashcam or OBD dongle left plugged in, a stuck interior or trunk light, a door or liftgate latch switch that never tells the body control module the car is closed, an infotainment or telematics unit that won’t power down, a sticky relay, or an alternator diode leaking current. A weak or aged battery can also make a small, normal draw look much worse.
