there are 2 types of wiring, one is wire to your batt where it continuous suck your batt, the other is wire to your ignition where it will shut off when the engine shuts off. and also, if you are using finevu cr300 or other cameras with powermagic, it basically stops power supply once it detects the batt's voltage drops below a certain limit. if your camera has motion detect functionality, you can also use it so as to not consume that much batt.
Perhaps this
link may offer some information