Why do batteries fail in winter

Most of us have had that horrible feeling when the car battery suddenly decides to fail and all you hear is “click, click”, why does it seem more likely in winter?
1. As the temperature decreases so does the amount of available cranking power
2. Colder temperatures increase the thickness of the engine oil, making the engine harder to turn over

In summer when the outside temperature is 26.7 C, a fully-charged battery delivers 100% of its cranking power available to start an engine that is easier to turn over because in the motor is warmer making the oil thinner.
So in winter when we go to start the car on a brisk 9 C morning, we have about 34% cranking power available to start a cold engine that will be harder to turn over because the oil in the engine is considerably cooler and thicker.

So to start our motor in winter we have
• Less available cranking power
• More energy required to turn-over the engine

This causes a greater load on the battery and ignition system to start the vehicle

So a battery in a fair condition may have easily started the car in summer, is more likely to fail in winter.

When we service your car, we check the batteries charge rate and general condition, we also clean the terminals to ensure it delivers the best cranking power to the vehicle.
Of course, sometimes the battery is just past its life expectancy.