EV battery health and real range, explained
Contents
Battery health and range are the two questions every used-EV buyer asks, and they are easy to confuse. This is the hub for both: what state of health (SoH) really means, why it matters more than mileage, and how we turn a car's lab range figure into a number you can actually plan around in Ireland.
State of health is not the same as range
These two get mixed up constantly, so it is worth being precise.
- State of health (SoH) is the percentage of the battery's original usable capacity that remains. It is a slow, structural figure that only moves over years.
- Range is how far the car will go right now, and it swings day to day with the weather, your speed, the heater and the terrain.
A healthy battery still gives you less range on a cold motorway run than on a mild town commute. That is normal. SoH is the stable number you compare between cars; range is the day-to-day experience that sits on top of it.
How EV batteries age
Battery capacity does not fall in a straight line. It typically drops a little faster in the first couple of years as the cells settle, then the curve flattens and degradation slows right down. That shape is why a well-kept older car can hold a surprisingly strong battery, and why a hard-used younger car can disappoint.
What accelerates ageing is heat and heavy fast-charging, not gentle daily use. A car that spent its life in a warm climate doing frequent rapid charges will usually show more wear than its registration date suggests, so always judge a car on its measured SoH rather than its age alone.
Reading real-world range: WLTP minus 17 percent
Every EV is sold with a WLTP range - an official lab figure measured under standard conditions. It is useful for comparing cars on a level playing field, but no one drives in a lab. Irish roads, weather and speeds return less.
To give an honest, like-for-like figure, ShamAuto shows a real-world range estimate of WLTP minus 17 percent on every listing. It is deliberately cautious and applied identically to every car, so you can trust the comparison. Here is how that looks across some common used models, using their catalogue WLTP figures:
| Model and battery | WLTP range | Real-world estimate |
|---|---|---|
| Nissan Leaf 40 kWh | 270 km | 224 km |
| Hyundai Kona Electric 64 kWh | 484 km | 402 km |
| Volkswagen ID.3 Pro 58 kWh | 425 km | 353 km |
| Tesla Model 3 RWD (Highland) | 513 km | 426 km |
| Kia EV6 77.4 kWh RWD | 528 km | 438 km |
The full method, and why 17 percent, is in real-world range vs WLTP explained. For what to expect when the temperature drops, see EV winter range in Ireland.
Putting it together when you buy
When you compare two cars, line up three things: the measured SoH, the real-world range, and whether the SoH is verified. A car with a strong, verified SoH and a realistic range that covers your daily distance is a better buy than a younger car with an unverified, weaker battery.
That is why every ShamAuto listing leads with battery health and real-world range, and why sellers who prove their SoH stand out. The practical, model-by-model how-to is in how to check battery SoH before you buy.