Published November 2026.
Cold weather leads to weak car batteries. A battery that coped all summer can fail on the first frosty morning, because the cold slows the chemistry inside it just as the engine needs more power to turn over. This guide covers how long a car battery lasts, how to test it, what a replacement costs in 2026, and whether you can change it yourself.
How long does a car battery last?
Most car batteries last around three to five years. Some go on much longer, and some fail sooner. What shortens a battery’s life:
- Lots of short journeys, which take charge out to start the engine without driving long enough to put it back.
- Standing unused for weeks at a time.
- Being run completely flat, especially more than once.
- Heat and cold: heat ages a battery, and cold exposes the weakness.
- A charging fault, such as a failing alternator, or something draining it while parked.
Signs your car battery is failing
- The engine turns over more slowly than usual, especially on cold mornings.
- Dim headlights or interior lights when the engine is off, or lights that dim when you start the car.
- Electrical glitches: the clock resets, the stop-start system stops working, or warning messages appear.
- The battery warning light comes on while driving. That usually means it isn’t being charged, which points at the alternator: see our dashboard warning lights guide.
- You’ve needed a jump start more than once recently.
- The battery case is swollen or leaking, or the terminals are heavily corroded.
How to test a car battery
The quickest home test is with a multimeter, which costs a few pounds. Many garages and parts retailers will also test a battery free of charge, with a tester that checks how well it holds up under load.
- Leave the car standing for a few hours, with everything switched off, so you read the battery’s resting voltage rather than a surface charge from driving.
- Set the multimeter to DC volts (the 20V range).
- Touch the red probe to the positive (+) terminal and the black probe to the negative (–) terminal.
- Read the voltage, then compare it with the chart below.
- For a second reading, start the engine: the voltage should rise to between about 13.7 and 14.7 volts, which shows the alternator is charging it.
A battery can show a healthy voltage and still fail under load, so if it reads well but the car still struggles to start, have it load-tested.
Car battery replacement cost in 2026
What you’ll pay depends mostly on the type of battery your car needs. Cars with stop-start need an EFB (enhanced flooded battery) or AGM (absorbent glass mat) battery, which costs more than a standard one.
| Battery type | Typical fitted price (approximate) | Used in |
|---|---|---|
| Standard (flooded) | About £100 to £200 | Older and smaller cars without stop-start |
| EFB | About £150 to £250 | Many stop-start cars |
| AGM | About £180 to £300 or more | Premium cars, and cars with stop-start and brake energy recovery |
As a guide, the RAC‘s average mobile mechanic prices for December 2025 to June 2026 run from about £206 for a Ford Fiesta to £264 for a Kuga, including fitting, testing and disposing of the old battery. Premium brands cost more again.
Some retailers fit a battery free with the purchase and others charge for it. On many newer cars fitting costs more, because the new battery has to be registered (coded) to the car’s computer.
How to change a car battery yourself
On an older car without stop-start, changing a battery is a simple job with a spanner or two. On many newer cars it’s worth paying a garage, because:
- Many cars need the new battery registering with a diagnostic tool, so the charging system treats it correctly. Without it, a new battery can wear out early.
- The battery may be hard to reach: under a seat, in the boot floor or behind trim.
- You may lose settings, such as radio codes, window positions and the clock.
If you do it yourself:
- Check the new battery matches the old one: size, terminal layout, type (standard, EFB or AGM) and capacity. Your handbook lists what fits.
- With everything switched off, disconnect the negative (–) terminal first, then the positive (+).
- Undo the clamp holding the battery down and lift it out (it’s heavy).
- Fit the new battery and its clamp, then connect the positive first, then the negative.
- Take the old battery back to the retailer or a recycling centre. Car batteries contain lead and acid, so they mustn’t go in household waste.
Does a car battery affect the MOT?
Yes, in one way. The MOT inspection manual (section 4.13) checks that the battery is secure and isn’t leaking. An insecure battery that could fall or short circuit, or a leaking battery, is a major defect and a fail. The tester doesn’t check how much charge it holds.
You can see every past MOT result and advisory on a car with our MOT history check.
Frequently asked questions
How much does it cost to replace a car battery?
Typically around £100 to £200 fitted for a standard battery, and £150 to £300 or more for the EFB or AGM battery a stop-start car needs.
How long does a car battery last?
Usually three to five years, depending on how the car is used. Lots of short trips and long periods parked shorten its life.
How can I tell if my car battery needs replacing?
Slow starting, dim lights and electrical glitches are the usual signs. A multimeter reading below about 12.4 volts after the car has stood, or a failed load test at a garage, confirms it.
Can I fit a standard battery to a stop-start car?
It isn’t recommended. A stop-start car needs an EFB or AGM battery; a standard one will wear out quickly and the stop-start system may stop working.
Can I charge a car battery instead of replacing it?
Yes, if it’s simply flat. A battery charger can bring it back, but if it keeps going flat, it’s time for a new one, or to find what’s draining it.
- GOV.UK: MOT inspection manual, section 4.13 battery
- RAC: car battery replacement costs (Dec 2025 to Jun 2026)
- How to jump start a car
- Alternator replacement cost
- How often should you service your car?
Check a car’s MOT history, including battery and electrical advisories, free with our MOT history check.