Why batteries are often flat
Lead acid batteries never fully recover from being flattened, and repeated flattenings render them useless. Several items in a car that run continuously even with the ignition off include the radio memory, the trip computer and the remote locking/alarm system. It makes no difference whether the car is locked or not - the alarm’s radio receiver is still listening out for a blip from your keyfob. These items will often flatten a good battery within 3 weeks.
