The car wasn't there when your friend and your partner returned. Where was it and how did it get there? Did the police drive it? If so, how did they start it?
It is clear that it was intended that the car be driven, because someone had gone for a battery. Of course, if there is compelling evidence that you were not to be the driver; that you were in a passenger seat when waiting and found, that someone else could drive the car and was meant to do so etc; then the defence of 'no likelihood' can be established.
If the car could not be driven at all, because of its mechanical state viz. no battery working, car broken down, then you could argue that nobody was going to drive it, drunk or sober. It's unfortunate if you told the police that someone had gone to get a new battery, since that suggests that the car would be driveable within an hour or so, which fact might cause the court to think that you would be driving it when over the limit. Still the fact remains that, when found and if left so, the car could not have been driven. If you'd invited the police to start it and they couldn't, you could have said that obviously you couldn't drive it either and you'd have to walk or get a cab or a lift. That could have saved you.