Most modern EV batteries lose around 1–2% capacity per year in normal UK use. After 8 years you're typically looking at 85–90% of original range. Heavy rapid-charging and constant 100% charges accelerate it.
Battery degradation is the biggest question UK EV buyers ask. Here's a straight answer from someone who sees real-world EV battery health on the diagnostic regularly.
What's normal
1–2% loss per year is the standard figure across Tesla, Kia, Hyundai, VW, Nissan and Renault data. After 100,000 miles most well-treated UK EVs still show 85–90% state of health.
What accelerates it
Constant rapid charging (50kW+) every week, leaving the car at 100% in hot weather, and deep-discharging below 5% repeatedly. UK climate is actually kind to EV batteries — cool, mild, rarely above 30°C.
How to check yours
Any EV specialist can run a state-of-health (SoH) scan in 20 minutes. Always do this before buying a used EV. A car showing under 80% SoH at 5 years old is a red flag.
Warranty cover
Most UK EV battery warranties cover degradation below 70% (some 75%) for 7–8 years or 100,000 miles. Keep service records — claims hinge on proof of proper care.
Does fast charging damage my EV battery? — Occasional fast charging is fine. Doing it as your main daily charge accelerates degradation noticeably over 5+ years. Use a 7kW home charger for daily, fast chargers for long trips.
At what point should I worry about degradation? — Under 80% state of health before the warranty expires — get it tested and lodge a warranty claim with proof.
More detail on: How much does an EV battery degrade in the UK?
The short answer above covers the usual case. Below is the extra detail a UK driver normally needs to act on it — how to narrow the fault down, what it should cost, and when it is worth paying a garage rather than carrying on. This is general guidance from a working mechanic, not a substitute for someone putting your own car on a ramp.
What a fair UK price looks like
Independent labour rates in Scotland and the north of England typically run £45–£75 an hour; main dealers routinely charge £110–£160. On most repairs the parts are the smaller half of the bill, so the labour rate and the book time decide what you pay. Ask for the quote split into parts and labour, ask whether the parts are OE, OE-equivalent (Bosch, Denso, Delphi, Ferodo, Pagid) or budget, and ask what the warranty is on the work. A garage that will not break a quote down is a garage to walk away from.
When a second opinion pays for itself
Any quote over about £400 is worth a second look, and any quote that involves replacing a component nobody has actually tested is worth challenging. Ask what test proved the part is faulty. On sensors and modules in particular, live data or a substitution test should come before a parts bill. It is entirely reasonable to say: show me the reading that tells you this is the fault.
What Bob would check first
Start with the cheap, common and visible: fluid levels and their condition, tyre pressures and wear pattern, battery voltage and terminal condition, and every connector and vacuum pipe in the area of the fault. A surprising share of electrical gremlins are a corroded earth or a chafed loom, and a surprising share of running faults are an air leak downstream of the sensor doing the complaining. Only after that does anything get unbolted.
When it is worth going to a main dealer
Three situations justify main-dealer money: an open safety recall (free), a live manufacturer warranty or goodwill claim, and coding or programming work that needs manufacturer-level software. Everything else — servicing, brakes, suspension, clutches, cambelts, diagnostics — an experienced independent will do to the same standard for a good deal less, and using an independent does not invalidate your warranty under UK block exemption rules as long as the correct parts and schedule are used.
Safe to keep driving?
Treat anything affecting brakes, steering, tyres, seat belts or visibility as stop-now, no matter how well the car appears to be driving. Overheating and low oil pressure are also stop-now: the damage curve on both is measured in minutes, not miles. Most other faults will let you drive gently to a garage, but if the car is in limp mode, losing fluid, or the fault changes how it steers or stops, get it recovered instead. Recovery is cheaper than a tow plus a new engine.
Get an answer on your own car
If you want this looked at properly for your exact vehicle, send the details and Bob will write back — make, model, engine, mileage, when the fault happens and any codes you have. You get a written reply from a qualified UK mechanic with 32 years on the tools, not a chatbot, and your money back if he cannot help.
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