Lol here we go again. Mr kybeng handing out solid advice again. He actually gave the same advice in the kia forte thread, i already told him he's gonna fry someone's car but apparently he missed that....worst case scenario the battery might explode in the person's face.

There's a reason why most modern cars have a big plastic cover on the +ve terminal on the battery, so idiots know not to touch that. If you pull the +ve and leave the -ve connected and accidentally touched the +ve cable on the chasis once it's removed there's a good chance you'll fry your car. Same with using a wrench on the +ve, the tail end of the wrench touch the chasis when working on the +ve terminal screw, you'll get the same result.

Always -ve first, putting money in your pocket kyheng.

just the -ve will do, the drain time will vary from car to car. some takes almost a day while some 30 mins. if you want to drain fast you'll need to know how to remove the ecu fuse.