well....found some useful article on battery drains...it's likely the case of Civic X i.e keyless entry..it might be the culprit...
"PROXIMITY KEYS
Lots of new cars are available with proximity keys. They're a great convenienceâall you need to do is walk up to your locked car with the key in your pocket or purse. As you approach the door, the locks pop open automatically. Plunk yourself in the seat and, with the key still in your pocket, thumb the starter button and drive away.
Guess how these things work. There's a radio receiver that continuously listens for the key's frequency. When the receiver hears a signal at its assigned frequency, it wakes up to see if the key is the one that matches the car. That draws more current for a minute or two, until the receiver abandons the possibility that it's about to unlock the door for master. This might be an issue if you leave the car parked for many weeks without starting it. Imagine the confusion of a car parked near the elevator door in a busy parking structure. Every proximity key that walks past makes it sit up and beg, draining your battery for a few minutes. Soon, dead battery.
This issue is even more profound in the case of hybrids like the Toyota Prius. The key receiver operates on 12 volts, as do most of the accessories. More importantly, the 12-volt battery operates the main computer that controls everything else, like the door locks. The Prius starter, however, operates off the 280-volt traction batteryâbut the main computer has to be powered up for anything to happen. Since it doesn't have to start the engine, the 12-volt battery of the Prius is very small, 38 ampere-hours. So while a 64-ampere-hour battery in a normal car can last for weeks of a proximity receiver checking for the right key, the Prius battery can run too low within a few days. Bottom line: Turn off the proximity-key function, from the Prius's electronic dashboard, whenever you're parking it longer than overnight. It might be possible to do this on other vehicles as well. Check the owner's manual."