EV battery health: what buyers ask and how to show it

The best way to prove your EV’s battery is healthy is a dated battery health report from a dealer for your brand or an EV specialist, backed by your battery warranty details and an honest range reading. The range figure on the dash proves very little on its own, because it’s an estimate, not a measurement of the battery.

This guide covers what “state of health” means, where to get a report, the charging questions buyers ask, the battery warranty and how to describe range without overselling it. Most of it applies to plug-in hybrids too.

Why is the battery the first thing EV buyers ask about?

The battery is one of the most expensive parts of an electric car, and a buyer can’t see inside it. A petrol car shows its age through service records, oil and the way it drives. A battery’s condition mostly sits in data the buyer can’t read on a test drive, so they ask you.

It helps to know what has actually moved used EV prices. CarsGuide research, reported by EV Central in January 2025, tracked average advertised prices on Gumtree, Autotrader and CarsGuide from January 2023 to December 2024. Prices for the Tesla Model 3 and Model Y, BYD Atto 3 and MG ZS EV all fell sharply. That report linked the falls to less demand for used EVs and didn’t blame worn batteries. Tesla also cut its new-car prices repeatedly over the same period. Our guide to why used electric car prices dropped covers that story in full.

So proof of battery health won’t undo a market shift. What it does is remove a reason for a buyer to offer less, because a buyer who can’t tell whether the battery is fine has to allow for the chance that it isn’t. We couldn’t find a government body or data provider that publishes figures on how battery health affects used EV prices in Australia, so be wary of anyone who quotes you a percentage.

What does battery “state of health” mean?

State of health, often shortened to SOH, compares how much energy the battery can hold now with how much it held when new. It’s usually shown as a percentage, where 100% means as new.

It is not the same as:

• State of charge: how full the battery is right now, the percentage on your dash.
• The range estimate: the car’s guess at how far you can go on the current charge. Many cars base it partly on recent driving, temperature and air-con use, so it can rise and fall from week to week.

Different tools work out SOH in different ways, and readings can move a little between tests. That makes one reading from a named source, with the date and kilometres on it, useful evidence rather than a final verdict. If you get two readings, compare like with like: the same tool, at a similar charge level.

There’s no reliable “normal” figure for a battery of a given age. It depends on the car, the chemistry and how it has been used.

Where can you get a battery health report?

Start with a dealer for your brand. When you book, ask whether they can run a battery health check and give you the result in writing, with the VIN, date and kilometres on it. Not every brand or dealer offers a printed report, so ask before you go. If the car is due for a service anyway, combine the two.

An independent EV specialist is the next option, and some offer written reports. A buyer may arrange their own check too, so it pays to know what yours says first.

Which charging questions will a buyer ask?

Expect some version of these, and answer honestly rather than guessing:

• Did you mostly charge at home or at public fast chargers?
• What charge limit did you usually set?
• Was the car often left full, or close to empty, for long stretches?
• Has it sat unused for weeks at a time?
• Has it ever shown a charging or battery fault?
• Which charging cables and adaptors come with the car?

Manufacturers give different charging advice for different battery chemistries, so there isn’t one right answer for every EV. BYD’s Atto 3 and Seal, for example, use LFP (lithium iron phosphate) Blade batteries, while other makes and models may use a different chemistry with its own guidance. If you followed what your owner’s manual says, tell the buyer that and point them to the page.

If your app or home charger keeps a charging log, a few screenshots answer most of these questions at once. For plug-in hybrids the questions are similar, plus how often the car ran on petrol. Our guide to selling a plug-in hybrid covers the charging gear to hand over.

What should you check in the battery warranty?

Many electrified cars carry a separate warranty for the high-voltage battery, on different terms from the rest of the car. Find the battery section of your warranty booklet and note five things:

1. The term: years and kilometres, and whether it’s “whichever occurs first”.
2. The start date: the date the cover is counted from. Hyundai’s main warranty, for example, runs from the first registration date. Where cover transfers, the next owner gets what’s left, not a fresh term.
3. What it covers: whether it mentions a minimum battery capacity, or only defects.
4. Conditions: any servicing, software or charging rules the cover depends on.
5. Transfer wording: phrases such as “balance of the warranty” or “subsequent owner”.

Here’s what three brands’ Australian pages said when we checked in October 2026. Terms change, and your booklet is the final word for your car.

You can read Hyundai’s warranty page and BYD’s service and warranty page for the full wording. We couldn’t confirm Tesla’s or MG’s current terms for this guide, so check your booklet or the brand’s Australian site.

Hypothetical example: an EV whose 8-year or 160,000 km battery cover started in June 2022 is sold in October 2026 on 60,000 km. The cover runs to June 2030 or 160,000 km, whichever comes first. If the balance passes with the car, the next owner gets up to three years and eight months or another 100,000 km, whichever runs out first.

If your booklet says the balance transfers, write it that way in your ad. “Battery warranty to June 2030 or 160,000 km” tells a buyer far more than “still under warranty”. Our guide on whether remaining warranty adds value covers the main factory warranty as well.

How do you describe range without overselling it?

Start with the rated figure for your exact variant, because variants differ a lot. A BYD Atto 3 Standard Range is rated at 345 km (WLTP) and the Extended Range at 420 km. Our guide to selling a used BYD Atto 3 explains how to tell them apart. The Mitsubishi Outlander PHEV that went on sale in August 2022 was rated at 83 to 87 km of electric-only range (WLTP). These are lab test figures for comparing cars, not a promise of what you’ll see on the road.

Then add what you actually saw, with the conditions. A line like this works in an ad or a message to a buyer:

Charged to [charge level] on [date], the dash showed [number] km of range. Mostly [city or highway] driving, around [temperature] degrees. Rated range for this variant when new: [rated figure] km ([test name, such as WLTP]). Battery health report from [source], dated [date], attached.

Fill in your own numbers. If you don’t have a report, leave that line out rather than guessing a figure.

A few things to avoid:

• Quoting the best range you ever saw on a mild day as if it’s typical.
• Writing “no battery degradation” unless a report says so.
• Giving a state of health percentage you can’t back with the report it came from.

On a Tesla, buyers will also ask which version you have. Our guide to selling a used Tesla Model 3 or Model Y explains the differences.

What else does a buyer check on a used EV?

Battery evidence is the headline, but an inspector or private buyer will usually also look at:

• Warning lights: any battery, high-voltage or charging warning on start-up.
• Charging: the charge port, its cover and latch, and whether the car takes a charge.
• Cables and adaptors: whether the portable charging cable and any adaptors that came with the car are there.
• Underbody: scrapes or impact damage near the battery pack, and any accident history.
• Software and recalls: whether the car is up to date and recall work has been done.
• Keys and accounts: key cards, phone keys, and whether your app account has been removed.

On recalls, check the VIN on the government’s vehicle recalls site before you sell. The search shows which recalls cover your car, but it may not show whether the work has been done, so keep the job cards. Some recalls involve the battery system. REC-006653, for example, covers Nissan X-Trail e-POWER hybrids built from 2022 to 2026, where a battery controller software fault may trigger fail-safe mode and loss of drive.

Teslas take updates over the air, and Tesla has fixed recalls that way, including a bonnet latch issue (REC-006042) and power steering assist software (REC-006300). An over-the-air fix may leave no workshop paperwork, so photograph the installed software version and ask the brand to confirm in writing that no recall is open on your VIN.

What will a valuer ask about your EV?

Anyone valuing an EV, whether a dealer, a car-buying service or a private buyer, covers the same ground as above, with two questions that matter more than on a petrol car. The first is the exact variant and battery size, such as Standard Range or Extended Range on an Atto 3, because two cars that look the same in photos can differ in range. The second is the warranty start date, so the battery cover left can be worked out.

If you have a battery report, say so when you enquire and have it ready to send. It answers several questions before the phone rings.

Your battery evidence pack

Before you ask for offers, put these in one folder or email:

• A battery health report from a dealer or EV specialist, with the VIN, date and kilometres.
• Dated photos or screenshots of any in-car battery or charging screens.
• The battery section of the warranty booklet, with the start date.
• Service invoices, including any software updates.
• Your VIN recall search, plus job cards or the brand’s written confirmation for any recall it lists.
• Your honest range line, filled in from a recent charge.
• A list of the charging gear that comes with the car.
• Charging history screenshots, if your app keeps them.

Selling an EV with the battery questions answered

With the pack ready, you can answer the battery question once, in writing, for every buyer, whether you sell privately, trade in or sell to a dealer. That leaves fewer reasons to discount the car for uncertainty.

If your EV or plug-in hybrid is 2021 or newer with 100,000 km or less, Sell Your Car Australia can give you a free, no-obligation valuation. We’re run by a valuer who has priced cars since 1992, and you get a genuine offer by phone from a licensed dealer, not an online estimate. Mention your battery report and warranty dates on the call.

If you accept, a deposit is often paid the same day and the inspection happens at a time and place that suits you. The balance goes into your bank account, and the car is collected only after you confirm the funds have cleared. If there’s finance owing, we deal with your lender directly to pay out the loan, then pay you any equity. No fees come out of the offer. Call 1800 73 55 73.