Why does my Jeep Grand Cherokee's battery need to be jumped every few days?

My neighbor has a 2001 Jeep Grand Cherokee and his battery keeps draining down after he lets it set for 2 - 3 days . He ask me to take a look at it for him and i found out the cigarette lighter was the culprit . If you do not have a voltage tester here is a simple and easy way to check for voltage drain . First make sure battery is fully charged then connect negative terminal to negative post on battery then take positive terminal and slightly drag it across positive post on battery if you get a little spark and ark you have a voltage drain. Now if you get lucky like me and remove your cigarette lighter from its socket and the spark and ark goes away your problem is fixed if not you may have to remove each fuse one by one until spark and ark is no more . Hope this helps