A lot of people think that a car that is switched off and locked won’t be draining its battery at all. But that’s not the case. Electronic equipment often imposes a constant drain on the car’s battery, and things like the stereo (for keeping stored radio frequencies) and any alarm system can create a constant draw on the battery. And when you think about it, even the remote central locking needs to be 'alive' all the time so that it can identify and act on your command to open the doors and prepare the car to be started.However, I wouldn’t expect a nearly new car battery to be unable to survive a single week of not being driven. So maybe there’s something else going on. It could even be that the battery itself is faulty and not holding a charge as it should.I’d be talking to the dealership as a fault with, say, a luggage area light staying on or any other piece of equipment not switching off when it should, is potentially a warranty claim. Just don’t expect Isuzu to cover the cost of a new battery. Like tyres and brake pads, batteries are considered consumables and are generally not covered by a new-car warranty. Although if it’s an electrical fault on the car that has caused the death of the battery, I reckon it’s an arguable case.