Getting an Electric Vehicle Value Appraisal: SoH Diagnostics

In an electric vehicle, the high-voltage battery is the single most valuable component. It can account for up to 50 percent of the entire vehicle's value. While the condition of a combustion engine can be roughly estimated from mileage and service history, the performance of a battery remains invisible without technical tools. A battery ages both by calendar time and through the number of charging cycles and individual usage behavior, such as frequent fast charging at high temperatures.

Anyone who wants to obtain a value appraisal for an electric vehicle must therefore take the State-of-Health (SoH) into account. A vehicle with an SoH of 95 percent has a significantly higher market value than an identical model with only 85 percent remaining capacity. Without a professional battery diagnosis, any valuation is speculative. This is where DIAVAG's Premium Battery Test comes in, going far beyond simply reading the fault memory. We analyze cell balance and internal resistance to make a well-founded statement about the energetic condition of the storage unit. This protects sellers from unjustified price deductions and buyers from costly bad purchases.

Time is a critical factor in vehicle transactions. DIAVAG has therefore radically standardized and mobilized the process of creating appraisals. You don't need to visit an inspection facility or leave your vehicle at a workshop for a day. The appraiser comes to the location of the asset, whether that's a home garage, a dealer's lot, or a company parking lot. The appointment takes place within 24 hours of the order being placed.

On site, the physical inspection takes less than 15 minutes. The appraiser uses a specialized hardware case containing calibrated measuring devices for all relevant parameters. These include an OBD2 scanner for the vehicle electronics, a paint thickness gauge to identify repainting and accident damage, and the Premium Battery Test. Documentation is carried out via a standardized photo app that ensures complete, tamper-proof recording of the vehicle's condition. The finished PDF appraisal is finalized by a senior inspector and delivered digitally the same day.

Many market participants advertise battery tests, but the depth of analysis varies considerably. Traditional inspection organizations such as TÜV or DEKRA often offer only a basic diagnosis that merely reads out the values stored in the battery management system (BMS). However, these values can be inaccurate or influenced by recent charging events. DIAVAG's Premium Battery Test goes deeper into the matter.

We measure not only the aggregated SoH value but also check cell balance and the charging curve. Poor cell balance indicates uneven aging of the individual battery cells, which can lead to capacity loss or even the failure of individual modules over time. Our test procedure delivers data on actual capacity in kilowatt-hours (kWh) and internal resistance. These technical parameters are the only reliable basis for a legally sound value appraisal. This level of detail is essential especially for high-value electric vehicles or when improper battery handling is suspected, in order to determine the real replacement value or market value.

An appraisal is only as valuable as its acceptance by third parties. Whether in an inheritance case, a divorce, an insurance claim, or a legal dispute: the qualification of the appraiser is decisive. All DIAVAG appraisers work to the standards of the BVSK (German Federal Association of Freelance and Independent Motor Vehicle Experts). This guarantees a high level of professional competence and a methodically sound approach.

In addition, DIAVAG meets the requirements of ISO/IEC 17020 Type A. This is the highest level of independence for inspection bodies. It means that DIAVAG has no vested interest whatsoever in the sale of vehicles, repairs, or insurance. We deliver exclusively a neutral assessment of the asset. For legal questions, such as the usability of the appraisal in a specific court proceeding, you should always consult a lawyer or notary. The DIAVAG appraisal serves as an objective basis of evidence, additionally secured by the signature of a senior inspector and, optionally, a notarial hash on the Polygon blockchain.

If you want to have a value appraisal for your electric vehicle created, you have several options available. The following table illustrates the differences between DIAVAG and conventional providers.

Online estimators are based solely on algorithms and market data, without ever having seen the individual vehicle. Inspection organizations are technically competent but often lack the specialized hardware for in-depth battery diagnostics across all manufacturers. DIAVAG closes this gap through mobility and technical specialization.

A key obstacle when commissioning appraisers is often unclear pricing. Hourly fees, travel costs, and charges for photos or measurement reports make the final sum difficult to calculate. DIAVAG relies on a strict flat-rate model. For a standard value appraisal (combustion car, boat, cargo bike), the price is auf Anfrages. For electric vehicles, which require greater technical effort due to battery diagnostics, the premium flat rate of auf Anfrages applies.

This price includes all services: travel within the regions (Hamburg, Berlin, Munich), the complete on-site inspection, the Premium Battery Test, and the creation of the BVSK-compliant PDF appraisal. There are no hidden surcharges. This transparency is especially important for private customers who need a reliable basis for calculating their vehicle sale. For commercial customers such as car dealers or fleet operators, we offer individual terms from a volume of 50 appraisals per month, which can also include an API connection to existing Dealer Management Systems (DMS).

Regulatory requirements for battery data transparency are steadily increasing. From February 2027, the EU Battery Passport will become mandatory for all new traction batteries in electric vehicles. This digital passport is intended to contain information on the origin of raw materials, the carbon footprint, and above all the current condition and remaining capacity of the battery. DIAVAG is already prepared for this development today.

Our appraisal structure is aligned with the future requirements of the EU regulation. By establishing standardized SoH measurement procedures early on, we help vehicle owners document the value trajectory of their assets seamlessly. A vehicle with years of regular DIAVAG battery reports will enjoy significantly greater trustworthiness on the used market. We see ourselves as a partner for preserving value in an increasingly electrified mobility world, where data integrity is becoming the most important commodity.

A decisive factor for the quality of a value appraisal is the independence of its creator. Many platforms that offer free valuations aim to purchase the vehicle themselves or broker it to partner dealers. In such cases there is an inherent conflict of interest: the appraiser has an interest in setting the price low to achieve a higher margin on resale. DIAVAG expressly distances itself from this business model.

We do not sell vehicles, we do not broker insurance, and we do not carry out repairs. Our only service is objective inspection and assessment. This strict separation of trading and appraisal is the basis for the high acceptance of our appraisals among banks, insurers, and legal authorities. When you have a value appraisal created at DIAVAG, you receive unbiased expertise that reflects solely the actual technical and visual condition of your electric vehicle. This neutrality is our most important asset and your greatest advantage in price negotiations or legal disputes.

In addition to private customers, DIAVAG also serves the B2B sector. Car dealerships and fleet operators face the challenge of efficiently and precisely valuing large inventories of electric vehicles, especially in the case of lease returns or bulk sales. Our processes are designed for scalability. Appraisal orders can be triggered automatically via a DMS API, and results fed directly back into the dealer's systems. This significantly reduces administrative effort and ensures consistent data quality across the entire inventory.

DIAVAG also gives independent appraisers the opportunity to become part of our network. For a list price of auf Anfrages, experts can purchase the preconfigured hardware case including the specialized software. This enables local appraisers to offer their customers the same high diagnostic quality and standardized BVSK appraisals that distinguish DIAVAG nationwide. In doing so, we promote the professionalization of EV valuation across the entire market and set new standards for technical inspections.