The Three Main Types
| Type | Full Name | Best For | Price Range |
|---|---|---|---|
| Standard (SLI) | Starting, Lighting, Ignition | Cars without start-stop | £50–80 |
| EFB | Enhanced Flooded Battery | Standard start-stop systems | £70–110 |
| AGM | Absorbent Glass Mat | Premium start-stop, mild hybrid | £100–180 |
Why Battery Type Matters
Start-stop systems put enormous strain on batteries — far more than traditional starting. Every time the engine stops at a traffic light and restarts, the battery cycles through a deep discharge/recharge. Standard batteries can’t handle this and will fail within months in a start-stop vehicle.
Can I Upgrade?
You can always upgrade to a higher-spec battery: standard → EFB → AGM. But you should never downgrade. An AGM battery in a standard car will work fine and last longer. A standard battery in an AGM car will fail quickly.
Frequently Asked Questions
What’s the difference between EFB and AGM?
EFB is an enhanced version of a standard flooded battery with better cycling ability. AGM uses glass mat separators that absorb the electrolyte, allowing deeper discharge cycles and faster recharging. AGM handles 3-4x more charge cycles than standard batteries.
How do I know if my car has start-stop?
If your engine automatically turns off when you stop at traffic lights and restarts when you lift the clutch or brake, you have start-stop. Check your dashboard for a start-stop indicator light.
Can I fit an AGM battery to any car?
Yes — AGM batteries work in any car. They’re overkill for non-start-stop vehicles but provide superior performance and longevity.
