I own a 2018 Silverado 1500.
Two days a year I volunteer with an Amateur Radio group and Law Enforcement to make sure no one throws objects off the Thruway Interstate bridges on Halloween. We each get assigned a bridge. We sit here for 2-3 hours and must keep our parking lights on.
I keep my truck in Accessory Mode, key position 1 to make sure the parking lights stay on and other functions. Is keeping the truck in this mode for 2-3 hours going to cause issues to the battery? I figure it can't be drawing that much power, and it's a large battery.
Thanks.
Klob is mistaken. Conventional starting car batteries should never be discharged that low. They were only designed to start the car, and then be immediately recharged. You should avoid discharging the below 75%. The lead mesh inside is thin and will break up permanently from deep discharge, sometimes causing internal shorts, and in some cases explosions. "Deep Cycle" or "Traction" batteries have thick heavy duty lead plates intended for deep discharge.
Using exterior lights and radios for 3 hrs could discharge a battery enough that the car may not start on a cold day. I would run the engine periodically for about 10 minutes to keep the battery from losing too much charge.
It draws current but will cause harm to a battery as long it does not fully drain.
It just wear and tear on the battery vs wear on engine keeping the car idling for 2-3 hours.
Think car battery can go 30% fully discharged without causing any major harm
