I just read this article on The Reader's Digest which writes to say
If you get behind the wheel only to discover that your car’s battery has given up the ghost — and there’s no one around to give you a jump — you may be able to get your vehicle started by dropping two aspirin tablets into the battery itself. The aspirin’s acetylsalicylic acid will combine with the battery’s sulfuric acid to produce one last charge. Just be sure to drive to your nearest service station.
Does this technique work to revive a flat car battery enough for one more start?