Most were for cars not starting due to battery failure and people forgetting to put anti-freeze in their radiators.

Instead, the extra slot is used for a backup in case of battery failure.

It remained operational for 4.5 years until a battery failure on June 21, 1977.

But it notes that battery failure almost always starts after the standard one-year iPod warranty runs out.

Today's batteries are designed to put out full power practically to the end of their lives, so battery failure can and does strike suddenly.

But battery failure is, for better or worse, no longer an excuse.

That eliminates at least one worry - loss of data because of battery failure - from your life.

The causes of the battery failures are still unknown.

No deaths or injuries have been linked to the battery failures, the company said.

It remained operational until a battery failure in 1981.