Of course, it's not always the battery at fault - often the alternator (or dynamo if it's really old) can be at fault - or even a duff fan belt!

I always got "duff" batteries checked before replacing - even if a custoemr insisted - sometimes it's not necessary!

Hillman, I think in your examples it was a case of Murphy's law, as despite the rain and awkward situation you were able to summon assistance. Sod's law is a more extreme version of Murphy's law. While Murphy's law says that anything that can go wrong, will go wrong (eventually), Sod's law requires that it always goes wrong with the worst possible outcome.

In this case however I would also concede that Resistentialism (the seemingly spiteful behavior manifested by inanimate objects) may apply in which case the battery will be replaced and then the new one will fail whilst the original one will be installed in the car of the garage apprentice where it will function without problems for many years.