Mercedes gets FIA boost: ADUO could help solve battery problems
The picture emerging from the FIA’s first evaluations of the new 2026 power units presents what appears to be a contradictory situation for Mercedes. On one hand, there is an awareness that the manufacturer has produced an internal combustion engine that is less powerful than the benchmark unit in the category, even if the overall power unit package remains arguably the strongest on the grid. That benchmark is believed to be the RBPT engine powering Red Bull and its sister team, Racing Bulls.
On the other hand, that very disadvantage could become a technical opportunity of enormous value.
At Brackley and Brixworth, the main focus is not the estimated ten-horsepower deficit compared to the class-leading engine. Instead, attention has shifted to the possibility of exploiting the benefits offered by the ADUO system, the regulatory mechanism designed to help manufacturers that are behind catch up during the homologation cycle of the new power units.
For the group led by Toto Wolff, the situation is particularly intriguing. Mercedes’ biggest concern does not appear to be the outright performance of the internal combustion engine, but rather the reliability of the entire electrical system, with special attention focused on the battery — a component that has significantly influenced the team’s season so far.
In this context, ADUO is more than a simple regulatory concession. It becomes a technical tool that could allow Mercedes to intervene extensively in one of the most critical areas of its project.
ADUO: a regulatory shortcut worth millions
FIA regulations state that a manufacturer can access ADUO benefits if it records at least a two-percent deficit compared to the most competitive internal combustion engine on the grid. The FIA determines this figure through sophisticated monitoring systems based on torque sensors installed in the transmissions. The resulting data remains exclusively in the hands of the governing body and is not shared with the teams.
For Mercedes, reaching the required threshold unlocks a series of advantages that go far beyond simply recovering performance. The package includes an additional development token, roughly three million dollars in extra funding for engine development, and an increase in the amount of permitted dyno testing hours.
While ADUO is technically a mechanism linked to the combustion side of the power unit, the regulatory concessions create opportunities that the engineering group led by Hywel Thomas could use to its advantage. The resources made available through the programme take on even greater importance in light of the issues that have emerged during the opening races, both on the Mercedes works cars and on customer teams.
The alternative would be to follow the traditional route of reliability modifications. That option is certainly permitted under the regulations, but it is much more restrictive. Mercedes would have to navigate a more complex approval process and, crucially, would not receive the additional budget or extra development hours guaranteed through ADUO.
The key difference lies in the scope of the permitted intervention. A reliability modification requires a manufacturer to demonstrate precisely which component is causing the problem and allows changes only to that specific element. ADUO concessions, by contrast, provide a far broader margin for development.
The battery mystery worrying Mercedes and McLaren
This is where the real technical challenge emerges. Engineers in Brixworth appear increasingly convinced that the numerous anomalies recorded throughout the season share a common root cause, even though the symptoms may vary from one incident to another.
The main suspect is the operation of the overtaking mode, commonly referred to as “override mode”. When the system is activated, the sudden increase in energy demand appears to create a condition that the electrical architecture cannot consistently manage. The result is a series of abnormal stresses that ultimately compromise the battery. The greatest challenge is identifying the exact source of the phenomenon.
The issue could originate from the MGU-K, the chemistry of the battery cells, the cooling system, the energy management software, the control electronics, or the charging and discharging strategies of the energy store. In short, there are many possible culprits. It is not even ruled out that the problem results from the interaction of several different elements at the same time.
It is precisely this uncertainty that makes ADUO access so valuable. The concessions would allow Mercedes engineers to analyse the entire energy chain without the limitations typically associated with a reliability modification request, enabling them to intervene simultaneously in multiple areas of the system.
The urgency becomes clear when examining the situation faced by several drivers. Each car is allocated three batteries for the season. Lando Norris has already used his full allocation, while Kimi Antonelli is preparing to install his third unit at the Austrian Grand Prix. George Russell is in a slightly better position thanks to the recovery of his first battery, which suffered less severe damage than in other cases.
Potential grid penalties represent only part of the concern. The more worrying aspect is the risk of retirements or compromised performances at crucial moments in the championship. Losing points due to reliability problems can have far more serious consequences than a few grid-place penalties on a Saturday.
For that reason, Mercedes’ deficit to Red Bull could ultimately become an unexpected asset. If ADUO genuinely allows the team to bring its electrical system and battery management under control, the horsepower sacrificed on the combustion side of the power unit may prove to be a reasonable price to pay in exchange for remaining firmly in contention for both world championships.
Leave a Reply