Originally Posted by
Trsnrtr
I had to put a battery in my three year old Odyssey, also $180. While shopping around, I was told that new cars have a lot of electronics and just opening the driver's door energizes a lot of different systems even before the car is started. I was warned against leaving doors open and to avoid using the accessories position with the motor off. Since I got this story from several sources, I have to assume it's true.
Not germane to your post, but every source told me that Honda batteries were junk and don't buy one as a replacement.
Not a Honda tech but GM cars do "wake up" several modules when the door is opened but this is not a problem as they will all go to sleep before the battery runs down.
You can use the acc position for a while but it may draw more current than older non computerized cars. Just don't overdo it.
GM cars also have accessory power which remains on for 15 minutes after you turn off the key, provided you don't open the door.