How to Check a Used EV’s Battery Health Before You Buy

Quick answer

The most reliable way to check a used EV’s battery is an independent battery health test, done at the car before you pay a deposit. Dashboard range and the car’s own battery readout are useful clues, but they aren’t independent measurements. In Melbourne, SMGLR does mobile AVILOO battery health checks on supported EVs and plug-in hybrids from A$299.

Why battery health matters on a used EV

The high-voltage battery is the most expensive component in an electric car, and its condition decides how far the car goes on a charge. Battery health is usually expressed as State of Health (SoH): the battery’s usable capacity today compared with when it was new.

Batteries are generally lasting well. In an analysis of 500,000 AVILOO battery tests across 20 popular EV models, cars at around 150,000 km typically still had 87–94% battery health. But battery health varied by up to 13.5% between the best and worst examples of the same model, so two cars with similar age and kilometres can be very different buys.

What you can check yourself

• Range at full charge. Ask the seller to show the estimated range at or near 100%. Treat it as a rough clue only: temperature, recent driving and settings all change the number.
• The car’s own battery readout. Some models show a battery health figure in a menu or app. It comes from the car’s own battery management system, so it isn’t an independent measurement.
• Battery warranty. Check how much of the manufacturer’s battery warranty is left and what it actually covers. Terms differ by brand, and most cover defects or capacity loss below a set threshold.
• How it was charged and stored. Ask about charging habits. The NRMA notes that excess degradation can happen when an EV isn’t charged the way the manufacturer recommends.

What an independent battery test adds

An AVILOO FLASH test connects to the car’s diagnostic port. You get a digital battery certificate or report with State of Health information, which AVILOO describes as an independent assessment rather than simply repeating the car’s own figure. SMGLR then explains what the result means for the car you’re looking at.

Plug-in hybrids and regular hybrids

Supported plug-in hybrids (PHEVs) can be battery tested the same way. Conventional self-charging hybrids, such as most Prius and Camry Hybrid models, aren’t covered by this test. For those cars, a full pre-purchase inspection with a diagnostic scan is the better choice.

When to test, and battery test or full inspection?

Test once you’ve shortlisted the car and before you pay a deposit, so the result can still change your decision or the price. If the battery is your main question, a standalone battery health check starts from A$299. If you’re buying the car, an EV pre-purchase inspection with battery testing also checks the rest of the vehicle, from A$499. Compatibility depends on the exact model, so we confirm it from the listing before you pay.

Sources

The Driven: study of 500,000 used-EV battery tests (September 2026)
NRMA: how to check EV battery health (April 2026)