Battery shutoff switch/radio presets

But those items don't draw current when they aren't being used. In your original post you stated your are trying to eliminate battery drain when the car sits. By bypassing the battery disconnect to the radio memory you will have the same amount of battery drain when the car sits. Unless of course there is a short or faulty component somewhere. In that case you should be trouble shooting that and fixing it, those are the kinds of issues that will leave you stuck on the side of the road at the most inopportune time.

See above. The battery drains when the air compressor runs due to the air bags fluctuating due to weather, etc. Also is a bit of a security device for the power door locks.