The Used EV Dilemma: How to Check a Second-Hand Electric Car's Real Battery Health Before Buying

It is relatively easy to purchase a used petrol or diesel car. The engine can be inspected, service records checked, and a test drive conducted to assess its condition. Used EVs are not the same. We know that the battery pack under the floor is often the most costly part of the car, but it's not always easy to tell from a cursory glance whether or not it's in good condition. Although the batteries in modern EVs are proving to be more durable than many had hoped, it is important to check the health of the battery before buying an EV. Before you pay for a used EV, here's how to check it out.

Quick Checklist Before Buying a Used EV

Before finalising a purchase:

• Check the battery's State of Health (SoH)
• Verify the remaining battery warranty
• Request an authorised diagnostic report
• Review charging habits and charging history
• Compare the current driving range with the original specifications
• Check service and software update records

State of Charge vs State of Health: Know the Difference

This is where many buyers get confused.

State of Charge (SoC)

State of Charge is simply the battery percentage shown on the dashboard. If the display shows 80%, it means the battery is currently 80% charged.

State of Health (SoH)

State of Health measures the battery's actual condition compared to when it was new. A new EV starts at roughly 100% SoH. Over time, battery capacity naturally reduces.

For example:

• 100% SoH = Battery performs like new
• 90% SoH = Battery retains roughly 90% of original capacity
• 80% SoH = Noticeable reduction in range

This is the number that truly matters when buying a used EV.

Step 1: Check the Full-Charge Driving Range

Ask the seller to fully charge the vehicle before inspection. Once the battery reaches 100%, check the estimated range displayed on the instrument cluster.

Now compare it with the vehicle's original claimed or real-world range.

For example, if a model that typically delivered around 250 km in real-world conditions now struggles to show 190-200 km at full charge, further investigation may be required.

This method is not perfectly accurate, but it provides a useful first indication.

Step 2: Get an Authorised Battery Health Report

This is the most important step. Unlike an engine, you cannot visually inspect a battery pack and determine its condition.

Instead, ask the seller to visit an authorised service centre and request a battery diagnostic scan.

The workshop can connect diagnostic equipment to the vehicle and access data from the Battery Management System (BMS).

The report typically reveals:

• Battery State of Health (SoH)
• Charging history
• Error codes
• Cell balance information
• Battery performance data

If a seller refuses to provide a battery health report, treat it as a warning sign.

What Is a Good Battery Health Score?

The table below can serve as a rough guideline.

Actual battery degradation varies depending on age, climate, mileage, and charging habits.

Check the Remaining Battery Warranty

Most manufacturers now offer battery warranties of up to 8 years or 1.6 lakh kilometres.

Before buying:

• Confirm how much warranty remains
• Verify whether the warranty transfers to the next owner
• Check whether any previous repairs affect warranty coverage

A used EV with five years of battery warranty remaining is generally far more reassuring than one approaching warranty expiry.

Review the Charging History

How an EV has been charged over its life can influence long-term battery condition. Many modern EVs maintain charging records through their connected-car apps.

Ask the seller about:

• Home charging habits
• Public fast charging usage
• Long-distance highway usage

Occasional DC fast charging is perfectly normal. However, a vehicle that has relied heavily on fast charging for years may deserve closer inspection.

Look at Service Records and Software Updates

Battery health is important, but it isn't the only thing that matters.

Check whether:

• Scheduled servicing has been completed
• Software updates were installed regularly
• Recalls have been addressed
• Previous battery-related repairs have been recorded

A well-maintained EV often provides a much better ownership experience than one with an incomplete service history.

Don't Judge a Used EV by the Odometer Alone

While mileage is still a factor, it's not the only one. An EV that has been well cared for and has 60,000 km on the odometer may be a safer investment than a car that has 25,000 km and has not been well maintained.

The condition of the battery, charging practices, service history and warranty coverage can tell a lot more about the actual condition of a used EV than the odometer ever will.

The Smart Way to Buy a Used EV

The positive side is that most EV batteries are holding up much longer than some of the early forecasts indicated. But battery replacement is still costly, so it's worth putting in a little extra effort to do some due diligence. A battery health report, warranty verification and charging history review can help you distinguish between a good deal and a bad deal. These checks are much more useful to most buyers than just the battery percentage on the dashboard.