How Long Do EV Batteries Really Last? A Hayes Garage's Honest Guide

Electric cars are still new enough that most owners have one big worry sitting in the back of their mind: what happens to the battery over time? Do you wake up one morning with half the range you paid for? Is it going to cost thousands to replace in five years?

The good news is that EV batteries are far more durable than people assume. But "durable" doesn't mean "never worth checking" — and that's what this post is about.

How fast do EV batteries actually degrade?

Under normal UK driving conditions, most EV batteries lose around 2–3% of their capacity per year. That means a car with a 200-mile range when new might realistically still be doing 170–180 miles after five years. It's a gradual curve, not a cliff edge — unless something's gone wrong with an individual cell or the Battery Management System (BMS).

Signs your battery needs a proper look

• Range dropping faster than expected. If you're covering noticeably fewer miles per charge than the manufacturer's stated range, that's usually the first sign something's off.
• Charging won't reach 100%. The car cuts off early or shows inconsistent readings — often a sign of cell imbalance rather than a simple charging fault.
• A battery or BMS warning light on the dash. Never ignore this one — it means the car's own systems have already flagged an issue.
• Charging is taking longer than it used to. Slower charge times at the same charger, same conditions, point to degradation in the cells themselves.

Why "check engine light" thinking doesn't work for EVs

With a petrol or diesel car, a warning light usually means "something specific broke." With an EV, the battery is a pack of hundreds of individual cells working together — degradation can be subtle and uneven, with some cells wearing faster than others. That imbalance often shows up in reduced range long before a warning light ever appears. This is why a proper diagnostic reads data directly from the BMS rather than waiting for a dashboard warning.

What a Battery Health Check actually involves

At Marieston Service Centre, our EV Battery Health Check plugs directly into the BMS — completely non-invasive, so it doesn't affect your manufacturer or battery warranty. In around 30–45 minutes we check:

• State of Health (SoH) percentage
• Cell voltage balance across the whole pack
• BMS fault codes
• Charge and discharge cycle history
• Thermal management system
• Charging port and onboard charger function
• 12V auxiliary battery condition

You leave with a written report and a clear pass, advisory, or replace recommendation — no guessing.

Should you wait for a warning light?

Given how gradual and uneven degradation can be, we'd say no. If your EV is a few years old, or you've noticed anything from the list above, it's worth getting a baseline SoH reading — even if everything turns out fine, you'll know exactly where you stand instead of guessing.

We test BEVs and hybrid (PHEV/HEV) packs alike, and it's walk-in friendly at our Hayes garage — 235 Yeading Lane, UB4 9AD — or you can book a slot online in advance. If you'd rather speak to us first, get in touch here.