Why Does My Car Battery Go Flat in Cold Weather?

Why cold weather kills weak batteries

A car battery makes its power through a chemical reaction, and that reaction slows right down in the cold. On a frosty morning the battery can deliver noticeably less power than it does in summer, just when the engine needs more to turn over thick, cold oil.

A battery that was already tired will often get through the autumn and then fail on the first properly cold morning. That is why the first frost brings a wave of cars that will not start.

Warning signs your battery is on its way out

The most common sign is a slow, laboured crank when you turn the key or press start, especially first thing in the morning. Other signs are dim headlights at idle, a battery warning light on the dash, electrics resetting (clock, radio presets) and a stop-start system that has stopped working.

Age matters too. Most batteries last around four to six years. If yours is older than that and the car is showing any of the signs above, get it checked before the weather turns.

Short journeys make it worse

Starting the engine takes a big chunk of charge, and the alternator needs time to put it back. Lots of short trips around Smethwick, Bearwood or West Bromwich, with lights, heater and heated screen all on, can leave the battery slowly draining day after day.

If most of your driving is short hops, a longer run once a week helps keep the battery topped up.

What to do if your car will not start

If the engine cranks slowly or just clicks, the battery is the most likely cause, but it is not the only one. A failing alternator, a faulty starter motor or something draining power while the car is parked can all look the same. Replacing the battery without checking can mean you are stranded again a week later.

Our guide to why a car will not start covers the other common causes. If you are not sure, call ER Automotive on 0121 461 6097 and tell us what the car is doing.

Get your battery checked before winter

Our vehicle health check at ER Automotive on Cranford Street, Smethwick includes the battery along with tyres, brakes, fluids and lights, so it is a good way to catch problems before the cold does. Book online or call us and we will fit you in.