Aviloo Test and Alternatives: Battery Diagnostics for Electric Cars

The high-voltage battery represents the most expensive individual component in an electric vehicle. It often accounts for between 30 and 50 percent of the total vehicle value. Unlike a combustion engine, whose condition can be assessed through compression tests or endoscopy, the condition of a battery remains invisible to the naked eye. The so-called state of health (SoH) describes the remaining capacity compared to new condition. A vehicle with an SoH of 85 percent has already lost 15 percent of its original storage capacity, which directly affects range and market value.

Precise diagnostics are essential for both buyers and sellers. While sellers can justify a higher price with a certified appraisal, buyers protect themselves against expensive follow-up damage. An Aviloo test or DIAVAG's Premium Battery Test provides the necessary data basis here. The analysis covers not only the pure capacity but also cell balance and internal resistance. These parameters indicate whether the battery is aging evenly or whether individual cells already show critical deviations that could indicate an impending defect.

Various approaches determine the health status of a battery. A well-known method is the Aviloo test, in which a dongle collects data over an extended period or during a specific discharge drive. This often requires active participation from the driver, who must drain the battery from 100 percent to below 10 percent. This process is time-consuming and often difficult to realize in the everyday context of a used-car purchase. In addition, it is often a pure data measurement without physical assessment by an expert.

DIAVAG takes a different approach. The appraiser comes directly to the vehicle with a specialized hardware case. The Premium Battery Test combines the reading of real-time parameters via the OBD2 interface with a standardized inspection of the vehicle's overall condition. Within less than 15 minutes on site, data on cell voltage, temperature management, and charging history is collected. Since this process is carried out by a BVSK-compliant appraiser, the result is not just a technical data sheet but a legally sound appraisal. This is particularly important when the document is to be used by insurers, banks, or in court.

At DIAVAG, the Premium Battery Test is an integral part of the premium appraisal. This fixed price covers the entire mobile service, including travel in the areas of Hamburg, Berlin, and Munich. Unlike simple diagnostic tools that merely read the value reported by the battery management system (BMS), DIAVAG validates this data through additional measurements and plausibility checks. A vehicle's BMS can be influenced by software updates or specific charging cycles, which is why an independent check using external hardware is crucial.

The hardware used includes calibrated OBD2 scanners and digital multimeters, deployed in a standardized workflow. The senior inspector who signs the final PDF appraisal checks the collected data for anomalies. This ensures that the reported SoH value corresponds to reality. Customers receive maximum certainty without hidden costs. While other providers often only check partial aspects of the battery, DIAVAG delivers a holistic assessment of the electric vehicle asset, which also covers the body, tire tread, and accident-free history.

A key difference between a purely technical measurement like an Aviloo test and a DIAVAG appraisal lies in legal usability. DIAVAG acts as an independent inspection body according to ISO/IEC 17020 Type A. This certification demonstrates the highest level of independence, as the company neither sells vehicles nor carries out repairs or brokers insurance. This neutrality is the fundamental prerequisite for recognition by third parties, for example in inheritance matters, divorces, or legal disputes.

All appraisers at DIAVAG work according to the standards of the BVSK (Federal Association of Freelance and Independent Vehicle Appraisers). An appraisal signed by a senior inspector meets the requirements for a professional valuation. For legal questions, a lawyer or notary should always be consulted, but DIAVAG provides the technical basis. Optionally, DIAVAG also offers a notarial hash on the Polygon blockchain to provide tamper-proof evidence of the immutability of the documentation and photos. The notarial hash creates trust that goes beyond simple workshop protocols.

From February 2027, the EU Battery Passport will become mandatory for all new batteries in electric vehicles and stationary storage systems with a capacity of more than 2 kWh. This regulation aims to increase transparency across the entire supply chain and lifecycle of a battery. Information on raw materials, carbon footprint, and above all the current health status must be digitally accessible. DIAVAG is already prepared for these regulatory requirements today and integrates the required data points into the Premium Battery Test.

For owners of electric vehicles, this means that regular documentation of battery condition is becoming increasingly important. Those who already rely on standardized appraisals today build a complete history that stabilizes residual value at a later resale. DIAVAG stores data in compliance with GDPR within the European Union. Through early adoption of these standards, DIAVAG offers future-proofing that goes beyond the mere snapshot of a simple battery test. This is particularly relevant for fleet operators who need to track the residual value of their vehicles over several years.

Vehicle valuations require efficient processes. A classic appointment at an inspection center or workshop requires planning, travel, and waiting time. DIAVAG solves this problem with a mobile deployment model. The appraiser comes to the asset's location, whether a private garage, a dealership yard, or a public parking lot. An appointment is usually available within 24 hours. The actual on-site inspection takes less than 15 minutes, as the workflow is optimized through digital checklists and calibrated hardware.

The finished PDF appraisal is delivered the same day. Fast turnaround times benefit dealers and fleet operators who need to make quick purchasing decisions. From a volume of 50 appraisals per month, DIAVAG offers individual terms and an API connection to dealer management systems (DMS). This allows the results of the battery diagnostics to be seamlessly integrated into existing sales processes. Private customers, on the other hand, benefit from the transparent fixed-price model for electric cars, which covers all costs including travel in the areas.

DIAVAG's Premium Battery Test goes deep into the vehicle's system architecture. Hundreds of data points are queried in real time via the OBD2 interface. A key value is cell voltage deviation (cell drift). If the voltages of individual cells diverge too much, this indicates uneven aging or a defect that throttles the battery's overall performance. In addition, internal resistance is measured, which provides information about thermal stability and efficiency during charging and discharging.

Analysis of the charging history provides insight into chemical aging. How often was the vehicle charged at a fast (DC) charger compared to slow alternating current (AC) charging. Frequent fast charging can accelerate chemical aging. The appraiser evaluates this data in the context of mileage and vehicle age. The technical diagnosis is supplemented by a visual inspection of the battery housing for mechanical damage or corrosion. Since DIAVAG also uses paint thickness gauges, it can also be determined whether repairs have already been carried out in the underbody area after a grounding impact, which can pose a significant safety risk for electric cars.

While providers such as Aviloo primarily focus on cars, DIAVAG covers a total of seven asset classes. In addition to electric cars, these include home storage systems, boats, construction and agricultural machinery, as well as micromobility solutions such as cargo bikes and e-scooters. The need for independent appraisals is particularly high for home storage systems (PV power storage). In real estate transactions, the value of the installed photovoltaic system, including storage, must be precisely determined. The Premium Battery Test is also used here to determine the SoH of the storage system.

Electric drives are also gaining importance in the maritime sector. A value appraisal for an electric boat requires specialized knowledge of the stresses on the battery in a humid environment. DIAVAG offers standardized processes for this. For construction and agricultural machinery, valuing residual value during business transfers or insurance cases is crucial. Through cross-asset expertise and a uniform hardware case, DIAVAG ensures that a valid and comparable appraisal is created for every class. This makes the company a versatile partner for private individuals and professional players alike.

The intended use determines the test method. Anyone who simply wants to know the condition of their private EV out of curiosity and has time for a test drive will find DIY solutions to be an option. However, as soon as it comes to buying or selling, legal protection, or professional valuation, an appraiser's report becomes indispensable. With its mobile service, fixed price, and BVSK-compliant certification, DIAVAG offers a package that combines technical precision with legal certainty.

DIAVAG's independence guarantees that the appraisal remains objective. Since no repairs or vehicles are sold, there is no self-interest in a particular result. As electromobility becomes standard, this transparency is the most important currency on the used market. With its focus on rapid availability and digital delivery, DIAVAG sets new standards in vehicle valuation. An appointment within 24 hours ensures that transactions are not unnecessarily delayed and that all parties can act based on verified data.