I lent my car to my sister who had to call out a mechanic when the car
battery died, he said they can suddenly fail and sold her another one.
There were no warning signs, no sluggishness, always started first
time and she had just driven it 50 miles down the motorway, stopped
briefly, went to restart and nothing, dead.
I've never heard of a battery doing this, has anyone else?

Thanks

Brendan.