Signs Your Car Battery Is Dying Before Winter Hits

The quick answer

The most common signs of a dying car battery are a slow, laboured start, dim headlights or interior lights when the engine is off, the battery warning light coming on, electrical gadgets playing up, and a battery that is more than four or five years old. If you notice any of these in autumn, get the battery tested before winter arrives.

Cold weather does not usually kill a healthy battery. What it does is expose a weak one. A battery that just about copes in September can give up completely on the first properly frosty morning in November.

Why batteries fail in winter

A car battery makes electricity through a chemical reaction, and that reaction slows down when it is cold. At the same time, a cold engine is harder to turn over because the oil is thicker. So on a winter morning your battery has less power available just when the starter motor needs more.

Winter driving also asks more of the battery once you are moving. Headlights, heated rear screen, blower fan, heated seats and wipers all draw power. If most of your trips are short, the alternator never gets long enough to put back what the start took out, and the battery slowly runs down day after day.

Warning signs to look out for

A slow crank is the classic one. Instead of a quick, crisp start, the engine turns over sluggishly for a second or two before it catches. It often gets worse on cold or damp mornings and better in the afternoon. Do not ignore it just because the car still starts.

It is also worth knowing that a battery can seem fine all summer and still be close to the end. Warm weather hides weakness because the battery has more power available and the engine is easier to turn. The first sign many drivers get is on a cold morning when the engine will not turn at all, or the dashboard lights up but the starter only clicks. A battery test in autumn catches that weakness while it is still just a warning, not a breakdown.

Dim or flickering lights are another clue. If the headlights or dashboard lights dip noticeably when you start the engine, or look weak with the engine off, the battery may be struggling to hold a charge.

The battery warning light on the dashboard, usually a red battery symbol, means the charging system has a problem. That could be the battery, but it could also be the alternator or its drive belt, so it is worth having both checked.

Other signs include the clock or radio resetting, central locking or electric windows being slow, stop-start no longer working, a clicking noise when you turn the key, and white or greenish crusty deposits around the battery terminals. A swollen or leaking battery case needs attention straight away.

How old is your battery?

Most car batteries last somewhere around four to five years, although that varies a lot with how the car is used. Cars that do lots of short journeys, sit unused for weeks, or have stop-start systems can wear batteries out sooner.

Where you park matters too. A car that lives outside all winter has a harder time than one kept in a garage, because the battery starts every journey fully cold. Cars fitted with alarms, trackers, dash cams wired in permanently or other accessories also draw a small amount of power while parked. That is normal, but if the car sits for a week or more it can be enough to leave a tired battery unable to start the engine.

Many batteries have a date stamped on the case or on a sticker. If yours is getting on in years and you have noticed any of the signs above, it is sensible to have it tested before the weather turns rather than wait for it to fail.

Simple ways to look after your battery

Try to give the car a longer drive every week or so, especially in winter, so the battery gets a proper charge. Switch off headlights, heater and heated screens before you turn the engine off so they are not all loading the battery on the next start.

If the car is going to sit for a long time, a smart battery charger or maintainer can help keep it topped up. Keep the terminals clean and tight, and make sure the battery is held down securely, as vibration shortens its life.

Modern cars with stop-start often need a specific type of battery, such as an AGM or EFB battery, and some need the new battery registering with the car's computer. Fitting the wrong type can cause problems, so it pays to get this right.

Get your battery tested in Walsall

A battery test only takes a few minutes and tells you far more than guessing. It shows how healthy the battery is and whether the alternator is charging it properly, so you are not replacing a good battery when the real fault is elsewhere.

If your car is starting slowly or the battery light has come on, bring it to MF Autocentre in Walsall before winter sets in. Call us on 01922 636820 or book online and we will check it over.