The only reliable way to check a used EV’s battery health is an independent State of Health (SoH) test that reads the battery management system directly – not the range shown on the dashboard. In Melbourne, an Aviloo battery test gives you a certified SoH percentage in minutes.
When you buy a used petrol car, the engine is the big risk. On an electric car, it’s the battery, and it’s the one component you can’t judge by looking at it. A used EV can look flawless, drive beautifully on a short test drive, and still have a battery that’s quietly lost 15-20% of its capacity. That’s thousands of dollars of hidden depreciation the seller may not even know about.
Why you can’t trust the dashboard range
The range estimate on the screen is a prediction based on recent driving, not a measurement of battery health. It shifts with temperature, driving style and how the car was last charged. A car showing ‘380 km’ might have a healthier battery than one showing ‘400 km’ – the number simply isn’t a diagnostic. To know the truth you need the battery’s State of Health (SoH): its current usable capacity compared to when it was new.
The three ways to check EV battery health
Independent SoH test (best): A device reads the battery management system and calculates a certified State of Health figure. An Aviloo Flash Test takes about 3 minutes via the OBD port; the Premium Test analyses a full charge-discharge cycle for the most detailed result.
In-car battery screens: Some EVs show a rough health indicator, but they’re inconsistent and easy for a seller to misread or misrepresent.
Charge-to-100% range check: Charging fully and comparing displayed range to the original WLTP figure gives a rough clue, but it’s affected by temperature and calibration – useful as a sanity check, not proof.
What a healthy used EV battery looks like
Independent fleet data from Geotab’s battery study puts average degradation at about 2.3% per year, leaving a typical battery near 82% capacity after eight years. So a three-year-old EV with a genuine SoH in the low 90s is healthy; one already down in the 80s that early is a warning sign worth investigating.
Get it checked before money changes hands
A battery test only helps if it’s done before you pay. That’s why our mobile EV inspection comes to the seller’s location across Melbourne, runs a certified battery test plus a full mechanical and electronics check, and gives you a clear report the same day – so you either buy with confidence or walk away before it’s your problem.
Instant Auto Reach brings a mobile EV inspection with certified Aviloo battery testing to you anywhere in Melbourne. Call 0402 220 178 or book online – 7 days a week.
Frequently Asked Questions
Can you check EV battery health without special equipment?
Only roughly. You can charge to 100% and compare the displayed range to the car’s original rating, but that’s affected by temperature and calibration. A proper State of Health reading needs a device that reads the battery management system, like an Aviloo test.
What battery health percentage is good for a used EV?
It depends on age and kilometres. Roughly 2.3% loss per year is normal, so expect low-to-mid 90s for a 2-3 year old car and low 80s by around eight years. Anything well below that range for the age is a red flag.
Does a pre-purchase inspection include battery testing?
Ours does. We run a certified battery State of Health test alongside the full mechanical, electronics and structural inspection so you get the complete picture of a used EV, not just the mechanical side.
