The Battery Can Be 40% of the Car. That Changes the Write-Off Sum.

An electric vehicle total loss is not a petrol total loss with a different badge. When one component can carry up to 40% of the vehicle's value, and cannot always be inspected to a conclusion, the write-off threshold, the salvage figure and the customer conversation all behave differently. This piece is about that arithmetic, and about what a total loss desk should be recording on EV files now.

A note on scope. We have written before about why more UK vehicles are being scrapped than repaired. That was the general trend. This piece is about one mechanism inside it: what happens to the repair-or-replace sum when the most expensive part of the car is also the hardest part to assess. We are not re-explaining write-off categories either; that piece covers the ABI's 2025 salvage code and its EV battery rules.

Why is an EV total loss a different calculation?

Because the repair-or-replace decision on a petrol car is spread across many components, and on an electric car it can hinge on one.

A conventional write-off compares repair cost with pre-accident value, and the repair cost is built from a long list of medium-priced parts and labour. No single line dominates. On a battery electric vehicle, the high-voltage battery can dominate on its own. If the battery is on the estimate, the estimate is often past the threshold before anyone has priced a panel.

Thatcham Research put it plainly when it launched its EV Blueprint on 3 March 2026: with batteries accounting for up to 40% of a vehicle's total value, even minor collision damage can result in a total loss, particularly as the vehicle depreciates. The same release reported a Thatcham and CEBR survey in which battery issues were the primary concern for 44.6% of insurers and 41.7% of repairers.

This is not a niche. Solera's Matthew Freeman told ARC360 in May 2026 that EVs now make up 14% of the UK parc, against 1% in 2015. Consumer Intelligence, citing SMMT data, put battery electric vehicles at 27.5% of new registrations in July 2026. The files are already arriving.

How much of an electric car's value is the battery?

Up to 40%, on Thatcham Research's figure, and the share rises as the car ages.

That second clause is the one that matters. A replacement pack is priced as a new part while the vehicle is priced as a used one, so the gap widens every year.

Thatcham's 2023 report for Innovate UK, Impact of BEV Adoption on the Repair and Insurance Sectors, quantified this. Replacement high-voltage batteries then ranged from around £14,200 to around £29,500, and Thatcham's depreciation modelling showed a replacement battery exceeding the used value of the vehicle after only one year. Those figures are three years old and prices have moved, so treat them as the shape of the problem rather than today's number. The shape has not changed.

Thatcham's illustration in the 2026 Blueprint is a three-year-old EV with minor side impact damage to a battery mounting bracket. Under current manufacturer procedures, casing damage often mandates a new battery, and the new battery costs more than the car. The vehicle is otherwise repairable. It is written off anyway.

What happens when the battery cannot be inspected to a conclusion?

The decision gets made on uncertainty rather than on damage, and uncertainty resolves towards total loss.

On a petrol car an engineer can usually see what is broken. On an EV the pack sits sealed under the floor, and the question after an impact is not "is it damaged" but "can anyone prove it is not". Thatcham's 2023 report found a lack of affordable or available repair solutions and inadequate post-accident diagnostics, and noted that until a consistent diagnosis and repair methodology exists, the repair will require battery replacement. The 2026 Blueprint asks for accessible diagnostics and clear damage assessment guidelines precisely because, three years on, that gap is still open.

Two other 2023 findings explain why underbody incidents in particular reach a total loss desk. Thatcham's expert assessment put the probability of battery damage from an underbody impact at around 85%. And it observed that dropping hard off a kerb or striking a large pothole, which would rarely generate a claim on a petrol car, puts the battery at risk on an EV.

Then the overheads. Government guidance on fire risk puts the safe distance for a damaged EV awaiting repair at 15 metres from other vehicles or structures. Using manufacturers' own average quarantine radius, Thatcham calculated that an outside storage area with room for 100 cars could safely hold two, a reduction of around 98%. Every day of that is storage and hire cost on the file, pushing the sum further towards a write-off.

Thatcham's chief executive, Jonathan Hewett, said in March that the industry is "seeing too many repairable vehicles written off". Nobody in the chain is acting unreasonably. The information needed to decide differently is not available at the moment the decision has to be made.

What does that do to the write-off threshold in practice?

It moves the threshold without anyone changing the rule.

The rule is the same for every vehicle: repair cost against pre-accident value, with the insurer's own percentage applied. What changes on an EV is how fast the repair side fills up. A battery line, a quarantine line, a specialist transport line and a longer key-to-key period can take a modest-looking impact past the threshold before the bodywork is assessed.

The cost data is consistent with that. Thatcham's 2023 figures had BEV claims around 25.5% more expensive than ICE and taking around 14% longer. At ARC360 in May 2026, Thatcham's Dan Harrowell reported EV repair costs down 10.7% over three years as repairers gain experience, but still around 25% higher than ICE, with repair times still 14% longer.

One honest caveat, and it is Thatcham's own. The 2023 report said it was impossible to quantify whether total loss rates are higher for the current generation of EVs, because there are too many confounding factors. Nothing we have seen since publishes a clean UK EV total loss rate. The argument here is about the mechanism, which is well documented, not a headline rate, which is not.

Why is an EV with an unknown battery hard to value at salvage?

Because the salvage buyer faces the same unanswered question the engineer did, and prices for the worst case.

On a petrol write-off, salvage value is a fairly predictable function of age, model and damage. On an EV, the most valuable component may be sound, partially damaged or unusable, and the buyer often cannot tell from the listing. Thatcham's 2023 review with Synetiq found that of the vehicles and manufacturers surveyed, 48% had repair methods and parts for repairable batteries, 28% supported partial repair, and 24% had batteries that could not be repaired at all. A buyer bidding blind assumes the last of those.

The market is starting to respond. In July 2026 Copart UK introduced an EV Battery Health Report, produced with the diagnostics specialist Aviloo, giving auction buyers an independent health score, voltage data and fault identification where available. That is a market telling you what it was missing. Where a battery health report exists, it changes the salvage figure, and the salvage figure changes the settlement if the customer retains the vehicle. The three valuation arguments we set out in June apply to pre-accident value; on an EV, the salvage deduction needs the same evidential care.

Why is the customer conversation harder than a petrol write-off?

Because the customer can see the car, and the car looks fine.

An EV written off for battery uncertainty can have a scuffed sill and nothing else visible. Explaining that a three-year-old car is a total loss because a component the customer cannot see might be damaged in a way nobody can confirm is a different conversation from any a petrol desk has run.

There is a second layer. Consumer Intelligence, in research published in August 2026, tested 100 Chinese EV risks across the four main comparison sites and found 18% of insurer brands returned no quote at all, with the rest pricing the segment unevenly. That is vendor research and should be read as such, but it points at something a total loss desk will feel: unfamiliar brands, unfamiliar parts networks and thinner valuation data on the segment growing fastest. Chinese-owned manufacturers took 19.6% of UK registrations in the first seven months of 2026, on the same source.

That customer often also has outstanding finance on a vehicle that depreciated faster than expected. Under Consumer Duty, the conversation needs to be clear, consistent and recorded, in a form the customer can read back later.

What should a total loss desk capture on EV files now?

More than it captures on a petrol file, and from first notification.

We do not hold EV file data of our own to publish, so this is not a benchmark. It is the list of things that, on the evidence above, decide the outcome and are most often missing from the record.

Impact zone and mechanism. Underbody, side sill, single or multi-zone. Collision or road hazard. This determines whether the battery is in play at all.

Battery assessment status. Inspected or not, by whom, by what method, with what result. If not inspected, record why. "Manufacturer procedure mandates replacement on casing damage" is a different reason from "no diagnostic capability available", and both differ from "damage confirmed".

Battery health evidence. Any state-of-health report, dealer diagnostic or independent test, dated. If a salvage-stage battery report exists, get it on the file before the salvage deduction is agreed.

The cost lines that pushed it over. Battery, quarantine, storage, specialist transport, extended hire. The file should show which lines took it past the threshold.

The valuation basis. Which guides, on what date, and how many live comparables were found. For newer brands that number will be small, and someone will ask.

What the customer was told about why. Not just the figure. The reason a car with a scuffed sill is being written off, in plain words, dated.

None of this is exotic. It is the evidencing discipline we argue for on every total loss file, applied to a vehicle type where the deciding facts are less visible.

The point

The arithmetic on an EV total loss is not broken. It is the same sum, with one input that can be as much as 40% of the answer and cannot always be checked.

Thatcham's Blueprint is an attempt to fix that at the design and diagnostics level, and it will take years. Meanwhile the files keep arriving, and the only part of the problem inside an AMC's control is the record. A desk that can show why the battery was in play, what was known about it, and what it did to the figure will settle faster and defend better than one that recorded a total loss and a number.

To see how TotalSettle structures an EV total loss file so the battery question is captured rather than assumed, book a demo.

Craig Budsworth is Industry Advisor at TotalSettle. He works on the legal and regulatory side of motor claims, covering valuation disputes, Consumer Duty evidencing and the case law that decides how claims are settled.