#15
ยท
They use the CAN bus and ignition/accessory states very well to control off current draw. There is absolutely no reason in a modern vehicle to be concerned about possible battery drainage for anything other than lights or if there is an always on 12V outlet with something plugged into it. I don’t think the Ascent has an always-on (non-accessory) outlet. If a component in a car stays on in the true off state (after all timeouts) it is either a light that was intentionally left off of the BCM control or it is malfunctioning, or a door/liftgate switch is open and they didn’t implement a timeout for that condition. Some exceptions come in with variance from OEMs, but what I said is fairly typical.
The only realistic concern is any accessories plugged into 12V accessory outlets. Even modern alternators/batteries can allow states that send transients and spikes which could damage a device, but most accessories have adequate filters, and those issues are usually with a failing battery or alternator. The most severe circumstance is when jump starting a vehicle and a few things that can happen at that time, I personally recommend unplugging accessories when jump-starting, and to minimize current draw turning off everything that can be turned off. All installed components in a vehicle are designed and tested to have immunity to transients, spikes and noise. Reverse polarity, high voltage, etc. should blow a fuse as a worst case and not damage a component.
All that said, I think whatever user controllable state you leave the vehicle in is the state it should come up in.
