A dead 12V battery after an overnight park usually means something is staying awake or a module isn’t sleeping.
Start with battery health, aftermarket accessories, and a proper parasitic draw test before replacing parts.
Why your Lightning Cat is losing charge overnight
On the ORA Lightning Cat, the big high-voltage pack is not usually the thing that “drains overnight” in this scenario — it’s the 12V battery being pulled down by a parasitic draw. A small amount of standby current is normal because the car keeps keyless-entry receivers, telematics, alarm logic, and some control modules alive. The problem starts when a module fails to go to sleep, an aftermarket dashcam or OBD dongle stays powered, an interior light or door/liftgate switch sticks, or the car keeps waking for connected-car/OTA activity. A weak 12V battery makes it look worse: it may still start the car but won’t hold enough reserve overnight.
