Table of Contents
Why the battery is a game-changer for used EVs
How a battery degrades: what you need to know before buying
How to check the actual state of health of the battery before buying
Diagnostics tools: which ones to use and how to interpret them
Models with the best and worst battery history
How battery health affects purchase and resale prices
How to communicate real-world range to the final buyer
Battery warranties: what each manufacturer covers
Frequently Asked Questions
Why the battery is a game-changer for used EVs
In an internal combustion engine (ICE) car, the most expensive component that can fail is the engine, costing between €3,000 and €8,000 in a severe case. In an electric vehicle, the main battery can cost between €8,000 and €20,000 depending on the model and capacity. And unlike an engine, which either works or doesn't, a battery degrades gradually and silently.
This has a direct consequence for the used car dealership: two cars of the same model, year and mileage can have completely different market values if one has 90% battery capacity and the other has 72%. A buyer who doesn't know this will pay the price of the good one for the deteriorated one, and will file a claim when they discover it.
The battery verification process is not optional for EVs: it is as basic as checking the mechanics before buying an ICE car. And in many cases, it is faster and cheaper.
For a broader view of the used electric vehicle market for dealerships, you can consult the article on used electric cars for dealerships.
How a battery degrades: what you need to know before buying
Battery degradation is the gradual loss of storage capacity over time and charging cycles. A battery that left the factory with 64 kWh may have 55 kWh of effective capacity after four years and 80,000 km, depending on how it has been used.
The factors that accelerate degradation are:
Frequent rapid charging (DC). Direct current rapid charging generates more heat in the battery than slow alternating current charging. Vehicles used mainly on motorways with rapid chargers tend to experience higher degradation than those used in urban environments.
Frequent charging to 100% and discharging to 0%. Keeping the battery constantly at the extremes of its charge range accelerates ageing. Vehicles whose owners always charged to 100% and drove until they were nearly empty have more degradation than those that have been kept between 20% and 80%.
Exposure to extreme temperatures. Intense heat and cold affect battery chemistry. In areas with very hot summers (southern Spain, Mediterranean areas), degradation of batteries without liquid cooling (such as the first-generation Nissan Leaf) is significantly faster.
Storage time with low charge. A vehicle that is left stationary for several months with a very discharged battery can experience additional degradation.
How to check the actual state of health of the battery before buying
Verification has three levels of depth, from the fastest and most accessible to the most precise.
Level 1: The vehicle's own indicators.
Many modern electric vehicles display the battery's State of Health (SOH) directly in the vehicle's info menu or on the manufacturer's app. In a Tesla, it can be seen from the central screen. In a Renault Zoe, from the diagnostics menu. In Hyundai/Kia, via the BlueLink or UVO app. Check the SOH before doing any other verification: if available, it is the most direct piece of data.
To integrate battery verification into the complete pre-purchase inspection process, consult the guide on what to check before buying a car to resell.
Level 2: OBD diagnostics with specialised software.
For models that do not display SOH natively, there are OBD diagnostic tools that read battery data. The most commonly used are:
Leafspy (specific to the Nissan Leaf): displays the SOH, battery bar count, charge cycles and temperature. It is the go-to tool for the Leaf and costs less than £5 in the app store.
BatterySpy / EVNotify: compatible with various models from different brands, they read data from the BMS (Battery Management System) and display the SOH and current capacity.
OBD11 / Carly: general diagnostic tools that, depending on the model, can read battery data in more or less detail.
The process is simple: you plug the OBD reader into the vehicle's port (under the dashboard), open the application on your phone or tablet, and within a few minutes you have the battery data.
Level 3: Real-world range test.
The most reliable but also the most time-consuming. Charge the vehicle to 100%, drive in mixed conditions (city and motorway at moderate speed) until the battery reaches 15-20%, and calculate the actual range obtained. Compare this figure with the model's factory WLTP range.
A rough guide: less than 80% of the original range indicates significant degradation. Between 80% and 90% is a normal range for a vehicle with several years of use. Above 90% indicates a vehicle with a battery in very good condition.
Diagnostics tools: which ones to use and how to interpret them
Tool | Compatible with | Cost | What it measures |
|---|---|---|---|
LeafSpy | Nissan Leaf | ~£5 (app) + OBD adapter (~£15) | SOH, cycles, temperature, bars |
BatterySpy | Various models | Free / freemium | Estimated SOH |
OBD11 | VW, Audi, Seat, Skoda | ~£60 (hardware) | BMS data depending on model |
Carly | Multi-brand | ~£80 annual | General diagnostics + battery |
Official manufacturer report | Models under warranty | Varies | Certified SOH |
How to interpret the SOH:
An SOH of 90% or higher in a vehicle over 3 years old and with 80,000 km is excellent. An SOH of 80-90% is normal, and the vehicle remains highly usable. An SOH below 75% starts to become problematic: the real-world range is noticeably reduced, and the buyer will notice it in daily use.
Models with the best and worst battery history
Not all models age the same way. The design of the thermal management system (whether the battery is liquid-cooled or has air ventilation only) is the most determining factor in longevity.
With good durability:
Tesla Model 3 and Model Y have very efficient thermal management, and their statistical degradation history is among the best on the market. A Tesla Model 3 with 150,000 km routinely retains over 85% capacity.
Hyundai Kona EV and Kia e-Niro are liquid-cooled and have demonstrated very good battery stability in hot climates.
BMW i3 has small batteries (which degrade less in absolute terms) and a very stable management system.
With frequent issues:
The first-generation Nissan Leaf (up to 2017) is the most documented case of rapid degradation. Lacking liquid cooling, it can lose 30-40% of its capacity in 5-6 years in hot climates. The second-generation Leaf (e+ with 62 kWh) has a better history but still lacks active cooling.
The Renault Zoe with a leased battery presents the additional issue that battery ownership may belong to Renault (under the lease contracts), which complicates the sale and raises concerns for the buyer.
Very old models (Peugeot iOn, Citroën C-Zero, Mitsubishi i-MiEV) have residual ranges of 60-80 km in the real world, making them difficult to sell except for very specific uses.
How battery health affects purchase and resale prices
The SOH is a pricing variable that many dealerships do not use systematically because they have not incorporated battery verification into their purchasing process. This leads them to buy and sell all EVs of the same model at the same price, regardless of the actual condition of the battery.
Indicative price adjustment scale based on SOH (on top of base market price):
Battery state of health (SOH) | Adjustment on market price |
|---|---|
90% or higher | Base market price or slightly higher |
80-90% | Base market price (no adjustment) |
70-80% | 10-15% discount |
60-70% | 20-30% discount |
Below 60% | Assess if viable for resale or for parts |
These percentages vary according to the model, original battery capacity and replacement cost. For a vehicle with a 64 kWh battery whose replacement costs €12,000, an SOH of 70% has a greater economic impact than for a vehicle with a 24 kWh battery whose replacement costs €4,000.
When buying, this data provides you with concrete arguments to negotiate the price when the SOH is low. When selling, it allows you to set the price more accurately and communicate exactly what the buyer is purchasing. To integrate this data into the general margin calculation per transaction, you can review the guide on how to calculate the margin on used cars.
How to communicate real-world range to the final buyer
The buyer of a used EV has one main question: will it get me where I need to go? Answering that question with concrete data, rather than referring them to the manufacturer's official range, is what builds trust and closes sales.
The WLTP range on the spec sheet is a laboratory reference that overestimates real-world range by 20-30% for most drivers. On a vehicle with a degraded battery, that gap is even wider.
The most useful way to communicate it:
"This model is certified for 300 km WLTP. In real mixed use, drivers typically get between 220 and 250 km. The battery of this car has an 85% state of health, which translates to a real range of approximately 190-210 km under normal conditions."
If the buyer lives 40 km from work, that directly answers their question: they can make the return journey without recharging. If they live 80 km away, they will need to recharge at their destination or en route.
Being specific and honest about the actual range is more effective than citing the WLTP figure. A buyer who discovers after purchase that the real-world range is lower than expected may file a claim for misleading advertising.
To see how to avoid claims related to incorrect vehicle information, consult the guide on how to avoid claims after selling a used car.
Battery warranties: what each manufacturer covers
Most manufacturers offer a specific battery warranty on new electric vehicles, which can be transferred to the subsequent owner if the vehicle is still within the parameters.
Manufacturer | Battery warranty | Trigger condition |
|---|---|---|
Tesla | 8 years / 160,000-240,000 km | SOH below 70% |
Renault | 8 years / 160,000 km | Excessive degradation |
Hyundai / Kia | 8 years / 160,000 km | Capacity < 70% |
Nissan | 8 years / 160,000 km | Less than 9 bars (Leaf) |
BMW | 8 years / 100,000 km | According to model conditions |
Volkswagen Group | 8 years / 160,000 km | Capacity < 70% |
Verifying whether the vehicle you are buying still has an active battery warranty is a valuable piece of information that can justify a higher sales price and builds buyer confidence.
To understand the legal obligations of the dealership if the battery fails after the sale, you can review the article on hidden defects in second-hand cars.
More than 750 dealerships already use Dealcar to manage their daily operations
Dealcar allows you to record the verified SOH at the time of purchase, the range test result, and any observation about the battery status in the file of each electric vehicle. With this information available in the vehicle’s file, the sales team can answer direct questions from the buyer with concrete data instead of relying on the manufacturer’s technical spec sheet.
If you want to see how it works, you can schedule a free demo at dealcar.io.
Frequently Asked Questions
Is it mandatory to inform the buyer of the battery state of health?
There is no specific legal obligation regarding the SOH, but there is a general duty not to provide false or misleading information about the vehicle's characteristics. Advertising the factory WLTP range for a vehicle with a battery degraded to 65% can be considered misleading information if the buyer reasonably expected that range.
What happens if the battery fails shortly after the sale?
If the failure is deemed to be a lack of conformity that existed prior to delivery (because the battery was already in a degraded state at the time of sale), the buyer can claim repair, replacement, or a price reduction under consumer protection laws. Documenting the SOH at the time of sale and reflecting it in the contract protects the dealership against this scenario.
How much does it cost to replace an electric car battery?
It depends on the model and capacity. A Nissan Leaf battery (24-40 kWh) can cost between €4,000 and €8,000 on the second-hand or remanufactured market. A Tesla Model 3 battery (75 kWh) can exceed €15,000 new. There are remanufactured battery options with warranties for some models that significantly reduce this cost.
Does a low SOH make the car unsellable?
Not necessarily. It depends on the model, the residual range, and the buyer profile. A Nissan Leaf with an SOH of 65% and a real-world range of 80 km can be perfectly useful for someone who uses it exclusively in town and has a charger at home. The key is to communicate it honestly and set the price accordingly.
Table of Contents
Why the battery is a game-changer for used EVs
How a battery degrades: what you need to know before buying
How to check the actual state of health of the battery before buying
Diagnostics tools: which ones to use and how to interpret them
Models with the best and worst battery history
How battery health affects purchase and resale prices
How to communicate real-world range to the final buyer
Battery warranties: what each manufacturer covers
Frequently Asked Questions
Why the battery is a game-changer for used EVs
In an internal combustion engine (ICE) car, the most expensive component that can fail is the engine, costing between €3,000 and €8,000 in a severe case. In an electric vehicle, the main battery can cost between €8,000 and €20,000 depending on the model and capacity. And unlike an engine, which either works or doesn't, a battery degrades gradually and silently.
This has a direct consequence for the used car dealership: two cars of the same model, year and mileage can have completely different market values if one has 90% battery capacity and the other has 72%. A buyer who doesn't know this will pay the price of the good one for the deteriorated one, and will file a claim when they discover it.
The battery verification process is not optional for EVs: it is as basic as checking the mechanics before buying an ICE car. And in many cases, it is faster and cheaper.
For a broader view of the used electric vehicle market for dealerships, you can consult the article on used electric cars for dealerships.
How a battery degrades: what you need to know before buying
Battery degradation is the gradual loss of storage capacity over time and charging cycles. A battery that left the factory with 64 kWh may have 55 kWh of effective capacity after four years and 80,000 km, depending on how it has been used.
The factors that accelerate degradation are:
Frequent rapid charging (DC). Direct current rapid charging generates more heat in the battery than slow alternating current charging. Vehicles used mainly on motorways with rapid chargers tend to experience higher degradation than those used in urban environments.
Frequent charging to 100% and discharging to 0%. Keeping the battery constantly at the extremes of its charge range accelerates ageing. Vehicles whose owners always charged to 100% and drove until they were nearly empty have more degradation than those that have been kept between 20% and 80%.
Exposure to extreme temperatures. Intense heat and cold affect battery chemistry. In areas with very hot summers (southern Spain, Mediterranean areas), degradation of batteries without liquid cooling (such as the first-generation Nissan Leaf) is significantly faster.
Storage time with low charge. A vehicle that is left stationary for several months with a very discharged battery can experience additional degradation.
How to check the actual state of health of the battery before buying
Verification has three levels of depth, from the fastest and most accessible to the most precise.
Level 1: The vehicle's own indicators.
Many modern electric vehicles display the battery's State of Health (SOH) directly in the vehicle's info menu or on the manufacturer's app. In a Tesla, it can be seen from the central screen. In a Renault Zoe, from the diagnostics menu. In Hyundai/Kia, via the BlueLink or UVO app. Check the SOH before doing any other verification: if available, it is the most direct piece of data.
To integrate battery verification into the complete pre-purchase inspection process, consult the guide on what to check before buying a car to resell.
Level 2: OBD diagnostics with specialised software.
For models that do not display SOH natively, there are OBD diagnostic tools that read battery data. The most commonly used are:
Leafspy (specific to the Nissan Leaf): displays the SOH, battery bar count, charge cycles and temperature. It is the go-to tool for the Leaf and costs less than £5 in the app store.
BatterySpy / EVNotify: compatible with various models from different brands, they read data from the BMS (Battery Management System) and display the SOH and current capacity.
OBD11 / Carly: general diagnostic tools that, depending on the model, can read battery data in more or less detail.
The process is simple: you plug the OBD reader into the vehicle's port (under the dashboard), open the application on your phone or tablet, and within a few minutes you have the battery data.
Level 3: Real-world range test.
The most reliable but also the most time-consuming. Charge the vehicle to 100%, drive in mixed conditions (city and motorway at moderate speed) until the battery reaches 15-20%, and calculate the actual range obtained. Compare this figure with the model's factory WLTP range.
A rough guide: less than 80% of the original range indicates significant degradation. Between 80% and 90% is a normal range for a vehicle with several years of use. Above 90% indicates a vehicle with a battery in very good condition.
Diagnostics tools: which ones to use and how to interpret them
Tool | Compatible with | Cost | What it measures |
|---|---|---|---|
LeafSpy | Nissan Leaf | ~£5 (app) + OBD adapter (~£15) | SOH, cycles, temperature, bars |
BatterySpy | Various models | Free / freemium | Estimated SOH |
OBD11 | VW, Audi, Seat, Skoda | ~£60 (hardware) | BMS data depending on model |
Carly | Multi-brand | ~£80 annual | General diagnostics + battery |
Official manufacturer report | Models under warranty | Varies | Certified SOH |
How to interpret the SOH:
An SOH of 90% or higher in a vehicle over 3 years old and with 80,000 km is excellent. An SOH of 80-90% is normal, and the vehicle remains highly usable. An SOH below 75% starts to become problematic: the real-world range is noticeably reduced, and the buyer will notice it in daily use.
Models with the best and worst battery history
Not all models age the same way. The design of the thermal management system (whether the battery is liquid-cooled or has air ventilation only) is the most determining factor in longevity.
With good durability:
Tesla Model 3 and Model Y have very efficient thermal management, and their statistical degradation history is among the best on the market. A Tesla Model 3 with 150,000 km routinely retains over 85% capacity.
Hyundai Kona EV and Kia e-Niro are liquid-cooled and have demonstrated very good battery stability in hot climates.
BMW i3 has small batteries (which degrade less in absolute terms) and a very stable management system.
With frequent issues:
The first-generation Nissan Leaf (up to 2017) is the most documented case of rapid degradation. Lacking liquid cooling, it can lose 30-40% of its capacity in 5-6 years in hot climates. The second-generation Leaf (e+ with 62 kWh) has a better history but still lacks active cooling.
The Renault Zoe with a leased battery presents the additional issue that battery ownership may belong to Renault (under the lease contracts), which complicates the sale and raises concerns for the buyer.
Very old models (Peugeot iOn, Citroën C-Zero, Mitsubishi i-MiEV) have residual ranges of 60-80 km in the real world, making them difficult to sell except for very specific uses.
How battery health affects purchase and resale prices
The SOH is a pricing variable that many dealerships do not use systematically because they have not incorporated battery verification into their purchasing process. This leads them to buy and sell all EVs of the same model at the same price, regardless of the actual condition of the battery.
Indicative price adjustment scale based on SOH (on top of base market price):
Battery state of health (SOH) | Adjustment on market price |
|---|---|
90% or higher | Base market price or slightly higher |
80-90% | Base market price (no adjustment) |
70-80% | 10-15% discount |
60-70% | 20-30% discount |
Below 60% | Assess if viable for resale or for parts |
These percentages vary according to the model, original battery capacity and replacement cost. For a vehicle with a 64 kWh battery whose replacement costs €12,000, an SOH of 70% has a greater economic impact than for a vehicle with a 24 kWh battery whose replacement costs €4,000.
When buying, this data provides you with concrete arguments to negotiate the price when the SOH is low. When selling, it allows you to set the price more accurately and communicate exactly what the buyer is purchasing. To integrate this data into the general margin calculation per transaction, you can review the guide on how to calculate the margin on used cars.
How to communicate real-world range to the final buyer
The buyer of a used EV has one main question: will it get me where I need to go? Answering that question with concrete data, rather than referring them to the manufacturer's official range, is what builds trust and closes sales.
The WLTP range on the spec sheet is a laboratory reference that overestimates real-world range by 20-30% for most drivers. On a vehicle with a degraded battery, that gap is even wider.
The most useful way to communicate it:
"This model is certified for 300 km WLTP. In real mixed use, drivers typically get between 220 and 250 km. The battery of this car has an 85% state of health, which translates to a real range of approximately 190-210 km under normal conditions."
If the buyer lives 40 km from work, that directly answers their question: they can make the return journey without recharging. If they live 80 km away, they will need to recharge at their destination or en route.
Being specific and honest about the actual range is more effective than citing the WLTP figure. A buyer who discovers after purchase that the real-world range is lower than expected may file a claim for misleading advertising.
To see how to avoid claims related to incorrect vehicle information, consult the guide on how to avoid claims after selling a used car.
Battery warranties: what each manufacturer covers
Most manufacturers offer a specific battery warranty on new electric vehicles, which can be transferred to the subsequent owner if the vehicle is still within the parameters.
Manufacturer | Battery warranty | Trigger condition |
|---|---|---|
Tesla | 8 years / 160,000-240,000 km | SOH below 70% |
Renault | 8 years / 160,000 km | Excessive degradation |
Hyundai / Kia | 8 years / 160,000 km | Capacity < 70% |
Nissan | 8 years / 160,000 km | Less than 9 bars (Leaf) |
BMW | 8 years / 100,000 km | According to model conditions |
Volkswagen Group | 8 years / 160,000 km | Capacity < 70% |
Verifying whether the vehicle you are buying still has an active battery warranty is a valuable piece of information that can justify a higher sales price and builds buyer confidence.
To understand the legal obligations of the dealership if the battery fails after the sale, you can review the article on hidden defects in second-hand cars.
More than 750 dealerships already use Dealcar to manage their daily operations
Dealcar allows you to record the verified SOH at the time of purchase, the range test result, and any observation about the battery status in the file of each electric vehicle. With this information available in the vehicle’s file, the sales team can answer direct questions from the buyer with concrete data instead of relying on the manufacturer’s technical spec sheet.
If you want to see how it works, you can schedule a free demo at dealcar.io.
Frequently Asked Questions
Is it mandatory to inform the buyer of the battery state of health?
There is no specific legal obligation regarding the SOH, but there is a general duty not to provide false or misleading information about the vehicle's characteristics. Advertising the factory WLTP range for a vehicle with a battery degraded to 65% can be considered misleading information if the buyer reasonably expected that range.
What happens if the battery fails shortly after the sale?
If the failure is deemed to be a lack of conformity that existed prior to delivery (because the battery was already in a degraded state at the time of sale), the buyer can claim repair, replacement, or a price reduction under consumer protection laws. Documenting the SOH at the time of sale and reflecting it in the contract protects the dealership against this scenario.
How much does it cost to replace an electric car battery?
It depends on the model and capacity. A Nissan Leaf battery (24-40 kWh) can cost between €4,000 and €8,000 on the second-hand or remanufactured market. A Tesla Model 3 battery (75 kWh) can exceed €15,000 new. There are remanufactured battery options with warranties for some models that significantly reduce this cost.
Does a low SOH make the car unsellable?
Not necessarily. It depends on the model, the residual range, and the buyer profile. A Nissan Leaf with an SOH of 65% and a real-world range of 80 km can be perfectly useful for someone who uses it exclusively in town and has a charger at home. The key is to communicate it honestly and set the price accordingly.
