State of Health is the single most important number when buying, selling, or owning a used electric car. It tells you what percentage of the battery's original capacity remains, and directly determines the car's real range and real value.
What Does SOH Mean?
SOH is a percentage of original usable capacity. 100% means the battery is at full original capacity. 85% means 15% has been lost, roughly 15% less range than when new. It's not the same as State of Charge (how full it is now). SOH is the size of the tank; SOC is how much fuel is in it.
What's Normal by Model?
Nissan Leaf 40kWh: 85–92% (air-cooled, varies widely)
Tesla Model 3/Y: 90–95% (excellent thermal management)
Hyundai Ioniq 5 / Kia EV6: 93–97% (800V, minimal stress)
VW ID.3/ID.4: 91–95% (liquid-cooled MEB platform)
MG ZS EV: 88–94% (varies by chemistry version)
BMW i3: 88–92% (conservative battery management)
The SOH Ranges
95–100%: Excellent. Near-new performance. Under 2 years or 20,000 miles. Premium pricing justified.
90–95%: Very good. Normal for 2–4 years, moderate mileage. No concerns.
85–90%: Good. 10–15% range reduction. Most used EVs at 40,000–70,000 miles sit here. Price should reflect it.
80–85%: Negotiate. 15–20% range loss. A 200-mile car delivers 160–170 in ideal conditions. Still usable but the price must reflect reality.
75–80%: Caution.Significant loss. Winter range could be 40–50% below original. Check warranty. Most guarantee 70% for 8 years.
Below 75%: Walk away, unless the price accounts for eventual replacement.
Why the Dashboard Isn't Proof
The SOH on your car's dashboard comes from the Battery Management System, an internal estimate that can drift from actual capacity by 3–8%. It's the car assessing itself. Not something a buyer should accept at face value when spending £10,000+.
An independent Aviloo test measures the battery separately from the car's own systems. The result is a certified, timestamped, QR-verifiable figure that any buyer, dealer, or insurer accepts as evidence.
Get Your SOH Measured
PAD offers Aviloo checks across Pontypridd, RCT, Cardiff, and South Wales. £95 for EVs, £95 for PHEVs. Mobile, certificate on site. Over 500 models covered.