12V Voltage Monitor Battery Alarm Clock Thermometer

[jim3cantos]

Hi:

I have bought one of these (see photo below) in eBay. It's not the nicometer but looks good in dashboard and provides time, in & out temp and 12v battery status.

Only one problem. Think's cigarette lighter doesn't cut power when car is shut down and backlight remains lit, so I have to disconnect manually to prevent too much drainage from 12v battery.

Is there any DIY way not too complicated to connect the clock other way in order to get it disconnected automatically?