Why Do Car Batteries Go Flat When The Weather Gets Colder?

A flat car battery is one of the most common reasons cars won’t start – and it often happens at the worst possible moment. The good news is that many flat battery problems can be prevented with the right care and checks. Here’s a simple look at the science behind it and what you can do to avoid being caught out as we go into the autumn and winter months.

How Car Batteries Work

Most cars use a lead-acid battery to store and deliver power.

• When charged, the battery stores energy in a chemical form.

• When discharged, that chemical energy is turned back into electricity to start your engine and power lights, wipers and electronics.

• This process is reversible, but batteries wear out over time, usually lasting 3–5 years.

  
  

Why Car Batteries Go Flat

1. Natural Self-Discharge

   • Even when not in use, batteries slowly lose charge.

   • Heat speeds this up, while cold makes it harder for the battery to deliver power when you start the car.

2. Parasitic Drain

   • Alarms, clocks and control units use a tiny bit of power all the time.

   • If your car isn’t driven often, this can flatten the battery.

3. Frequent Short Trips

   • Starting a car takes a lot of energy.

   • Short journeys don’t give the alternator enough time to fully recharge the battery, especially in winter when heaters, lights and wipers are working harder.

4. Battery Age and Condition

   • As batteries age, their performance drops.

   • Internal corrosion, sulphation and loss of electrolyte all reduce capacity, making the battery more likely to go flat.

5. Deep Discharges

   • Letting a battery go completely flat can permanently damage it, even if recharged later.

     
     

Looking After Your Battery

• Use your car regularly and take it on longer runs where possible.

• Keep battery terminals clean and free from corrosion.

• If the car is left standing for long periods, use a trickle charger to keep the battery topped up.

• Replace the battery once it shows signs of poor starting or struggling to hold charge.

  
  

Need Help With a Flat Battery?

At PW Auto Repairs in Newark, we offer:

• Battery checks while you wait.

• Supply and fitting of high-quality replacement batteries.

• Advice on keeping your car reliable through every season.

  
  

If your car is struggling to start or you’re worried about the condition of your battery, book in with our team today – we’ll make sure you stay on the road with confidence.

Call us on 01636 550852