Battery health is the single number that decides whether a used EV is a bargain or a liability – yet most buyers never check it properly. This 12-point inspection takes about an hour and requires nothing more exotic than the car itself, a charger, and attention. Work through it in order; the points build on each other.
Before you drive (points 1–4)
1. Ask for the state-of-health (SoH) reading. Many EVs show it in a hidden service menu, any competent workshop can read it via the OBD port, and some brands issue official battery certificates. Refusal to provide it is itself an answer.
2. Check the battery warranty transfer. Confirm the in-service date and remaining coverage – typically around 8 years/160,000 km against falling below 70% capacity.
3. Read the service history for battery events. Module replacements, coolant work on the pack, or repeated 12V battery failures deserve questions.
4. Check for open recalls by VIN – battery recalls are common enough that this two-minute check is non-negotiable.
On the test drive (points 5–8)
5. Note charge percentage and predicted range at the start, then again after a mixed 20 km drive, and do the consumption maths yourself.
6. Watch for sudden percentage drops – a pack that falls from 80% to 71% in minutes has cell-balance issues.
7. Push the accelerator hard once (safely). Weak packs sometimes limit power; sluggish response at moderate charge is a flag.
8. Listen for the cooling system. A pack fan or pump running loudly on a mild day suggests the battery is working harder than it should.
At the charger (points 9–12)
9. DC fast-charge the car during the viewing. Note the peak charging speed and compare it with what the model achieved when new.
10. Watch the charging curve. Healthy packs hold high speeds into the middle of the charge; tired packs taper early and hard.
11. Feel the pack area after charging – uneven hot spots along the underbody can indicate module problems.
12. Ask where the car usually charged. A life of gentle home AC charging ages a pack more slowly than daily fast-charging to 100%.
How to read the results
As a rule of thumb, expect roughly 2% capacity loss per year of normal use. A pack at 90%+ after five years is excellent; 85–90% is normal and priceable; below 85% deserves a meaningful discount or a walk-away. One weak point alone rarely kills a deal – a pattern of three or four does. For the full buying process beyond the battery, see our guide to buying a used EV: the 8 checks that actually matter, compare models in our longest-range EV ranking, and find inspection-friendly mechanics on our free local map.
