had the same problem, had noticed for a while the car was a bit sluggish on the starter, and feared i needed a new battery- but measuring it on a meter it was reading 12.72v which is good. so cleaned the battery terminals and inside of clamps with wire wool,covered them with vaseline.clamped them back togeather=
eureka!!all good
thanks for the help- the internet can be brilliant...
pug fan
February 2016