Battery: Guides by Make & Model

Standard, AGM or EFB — the right type depends entirely on your car. Find your specific model below.

Blamed First, Not Always Guilty

A car that won't start gets blamed on the battery more than any other part — usually fairly, but not always. Pick your make and model below for the specifics on telling a battery fault from something else entirely.

It's Not Just "A Battery" Anymore — Four Different Technologies Are in Use

Buying a like-for-like replacement used to mean matching a size and moving on. That's no longer true, and fitting the wrong technology to a modern car can genuinely damage the car's electrical system or cripple functions you didn't even know depended on the battery.

Standard flooded (SLI) batteries — Starting, Lighting, Ignition — remain the baseline for basic petrol and diesel cars without stop-start. Lead plates sit in free liquid electrolyte, delivering a short, high-current burst to fire the engine before immediately recharging. They're the cheapest option and typically last three to five years, but they cope badly with repeated deep discharge and simply aren't built for a car that switches its engine off at every red light.

EFB (Enhanced Flooded Battery) batteries add a polyester fleece to the positive plate that helps the active material stay put under repeated cycling, roughly doubling the charge-discharge cycle life of a standard flooded unit. This is the minimum acceptable technology for an entry-level stop-start system — a basic petrol car that switches off at traffic lights and restarts frequently.

AGM (Absorbent Glass Mat) batteries go further: rather than free-flowing acid, the electrolyte is absorbed into glass-fibre mats compressed tightly between the plates, making the whole unit sealed, spill-proof and highly resistant to vibration — genuinely useful, since vibration is one of the most common causes of premature battery failure. AGM batteries deliver roughly three times the cycle life of a standard battery, handle deep discharge far better, and their low internal resistance lets them deliver bigger cranking bursts and recharge faster, which matters on cars using regenerative braking to help top the battery back up. Most premium or heavily-optioned stop-start cars, and anything with regenerative braking, specify AGM as standard.

CMF (Calcium Maintenance Free) batteries use a calcium alloy in the plates that reduces corrosion and self-discharge, extending shelf life and giving roughly 15% better cold cranking performance than an old-style flooded battery, without the cost of EFB or AGM technology.

The rule that matters most: you can generally upgrade a car from EFB to AGM without any issue, since AGM does everything EFB does and more. Going the other way — fitting EFB or standard flooded to a car that came with AGM — is a genuine mistake that leads to rapid failure, dashboard warnings, and on some cars a stop-start system that simply refuses to engage at all.

Reading a UK Battery Label: Part Code, CCA, and Ah

Every UK-market battery carries a three-digit UK part code — numbers like 063, 096 or 019 — that standardises the physical case size and terminal layout, and it's the fastest way to confirm physical fitment before you even look at chemistry. Alongside it you'll find two performance figures worth understanding rather than just matching. Cold Cranking Amps (CCA) measures how much current the battery can deliver at -18°C for 30 seconds while staying above a minimum voltage — the figure that determines whether your car starts reliably on a freezing UK morning. Stop-start cars typically demand a CCA of 600 or more, against roughly 400 for a basic non-stop-start car, so don't assume a lower-rated battery that physically fits is an acceptable substitute. Ampere-hours (Ah) measures total capacity — roughly how many amps the battery can sustain over a set period — and matters most for how well the battery copes with running the car's electronics for extended periods with the engine off.

Many New Batteries Need to Be "Registered" With the Car

On cars fitted with an Intelligent Battery Sensor (IBS) or a broader Battery Management System (BMS) — increasingly the norm on anything built in the last decade — simply bolting in a new battery isn't the end of the job. The car's electronics need to be told a new battery is fitted, typically via a diagnostic tool, so the charging system manages it correctly from day one. Skip this step and you can end up with a battery that never charges quite right, dashboard warnings that don't make sense, or a stop-start system that quietly disables itself. If you're not doing this yourself, make sure whoever fits your battery does.

What to Actually Expect From Each Type, and When to Consider Upgrading

Realistic lifespans vary meaningfully by type: a standard flooded battery typically manages three to five years, EFB around four to six, and a genuine AGM battery five to seven years or more given its superior resistance to vibration — the single biggest real-world killer of batteries, more than age or a handful of deep discharges. If you do mostly short journeys, run a lot of accessories, or live somewhere the car sits unused for days at a time, upgrading from EFB to AGM (where your car's stop-start system supports it) is often worth the extra cost even before the original battery has failed, since urban stop-start driving is exactly the usage pattern EFB batteries cope with least well.

MOT Rules and Disposal

There's no dedicated "battery law" for private ownership, but a battery that's insecure, likely to move in its carrier, or visibly leaking is classed as a Major defect under the DVSA's MOT inspection manual — an automatic fail. Separately, lead-acid batteries are legally classed as hazardous waste in the UK and must never go in domestic rubbish; any retailer selling you a replacement is required to take the old one back for recycling, and local council recycling centres will also accept them.

Confirming Fitment Before You Buy

Battery type and capacity genuinely differ between standard and stop-start equipped versions of the same car, and fitting a standard battery to a stop-start car can cause premature failure since it's not designed for the frequent cycling involved. Always confirm the exact battery type and capacity for your specific trim before ordering, and check compatibility against your registration or VIN before buying — battery specification is one of the more common wrong-part mistakes given how similar different battery types look from the outside.

Warning Signs Worth Acting On

• Slow or laboured engine cranking — often the earliest sign, especially noticeable in cold weather.
• Dashboard warning light — a battery or charging system alert shouldn't be ignored, even if the car still starts normally.
• Electrical accessories behaving oddly — flickering lights or a stuttering infotainment system can point to inconsistent voltage.
• Stop-start system disabling itself — many cars automatically turn off stop-start when battery health drops, a useful early warning most drivers miss.

Swapping the battery itself is usually a straightforward 15-30 minute job — the registration step covered above is the part most DIYers miss, not the physical fitting.