Well I can leave mine over the weekend with the screen in standby. But when I go on vacation like I just did, I hook up a trickle charger basically and it keeps it good to go.
Before the charger I just unplugged it. I have a connector that has 4 wires I use for power, ground, ignition, and amp remote. I just need to unscrew the band around it, and pull the pieces apart. Then it is all good.
But there will always be a small draw for things like your remote door lock/unlock and all those fancy gizmos.
If it is drainging that fast, maybe you have a small short somewhere?