Honda has admitted that it still does not know the underlying cause of the battery failures affecting Aston Martin, after Lance Stroll suffered another retirement at the 2026 Brazilian Grand Prix. The Canadian’s latest failure followed an identical problem during Saturday’s running at Interlagos, raising fresh reliability concerns as the Japanese manufacturer attempts to resolve its technical difficulties ahead of the 2027 Formula 1 season.
The Brazilian Grand Prix offered Aston Martin a rare glimpse of competitive performance, with Fernando Alonso reaching Q3 for the first time this season and eventually finishing 12th. However, the team’s continuing Honda power unit problems overshadowed those encouraging signs, particularly after a disastrous run of five retirements from six possible finishes across the United States, Mexico City and Brazilian Grands Prix.
Fernando Alonso reaches Q3 but Aston Martin’s Honda power deficit persists
There were a few positives but, once again, far too many negatives for Aston Martin during the weekend at Interlagos. The most encouraging development came in qualifying, when Fernando Alonso made the most of the wet conditions to reach Q3 for the first time in 2026.
The two-time Formula 1 world champion benefited from his ability to exploit the slippery track, while Lewis Hamilton and Max Verstappen, both facing penalties, did not participate in the final part of qualifying. Fernando Alonso consequently started the Brazilian Grand Prix from the fourth row of the grid.
Unfortunately, his race was compromised almost immediately. On the opening lap, Oliver Bearman lost control of his Haas directly ahead of the Spaniard while exiting the Senna S, forcing Fernando Alonso to lose several positions.
Despite that setback, the Aston Martin driver continued fighting and ultimately finished 12th, although the familiar lack of straight-line speed from the Honda power unit remained a major limitation throughout the race.
The AMR26 was competitive through the corners at Interlagos, but its performance deficit on the straights was severe even in the damp conditions. At one point, the situation prompted another memorable gesture from Fernando Alonso, captured by the onboard cameras as he sarcastically waved at rivals overtaking him with considerably greater speed along the start-finish straight.
Fernando Alonso admits wet conditions masked Aston Martin’s weaknesses
Against the backdrop of Aston Martin’s extremely disappointing 2026 season, the Brazilian Grand Prix nevertheless represented one of the team’s more encouraging performances. Fernando Alonso not only reached the chequered flag but also spent parts of the 71-lap race battling cars that, under normal circumstances, he would encounter mainly when being lapped.
The Spaniard acknowledged that the wet conditions helped Aston Martin compensate for some of the limitations of the Honda power unit.
“It was definitely much better in the wet than in the dry,” Fernando Alonso admitted. “The pace was pretty good and it was a surprise; the car responded well throughout the race.”
“We’re still missing a huge amount of straight-line speed and it’s difficult to compensate for that, but considering where we are today, we managed to fight with the Ferraris at the beginning and towards the end we were even close to the Mercedes’ pace.”
“Taking into account everything we lose on the straights, the car performed very well in the corners. We weren’t happy at all during free practice, but in the race we found a better operating window. We know exactly where we need to make improvements.”
The performance highlighted a contrast within Aston Martin’s current package. While the AMR26 demonstrated encouraging cornering capabilities, the Honda power unit continued to prevent Fernando Alonso from making the most of the car’s potential.
That weakness has been a recurring feature of the season, with Aston Martin’s Honda reliability problems forming part of the wider technical difficulties experienced under the 2026 Formula 1 regulations.
Lance Stroll suffers 13th retirement as Aston Martin reliability crisis deepens
While Fernando Alonso at least managed to finish the race, the situation on the other side of the Aston Martin garage was considerably worse. Lance Stroll endured another frustrating afternoon, retiring on lap 30 while running 18th and 28 seconds behind his team-mate.
It was the Canadian’s 13th retirement of the 2026 season, rising to 14 if the Australian Grand Prix, where he was not classified, is also included. The latest setback was particularly concerning because it was caused by the same battery problem that had already affected his car during Saturday’s running.
“Battery problem,” was Lance Stroll’s brief assessment of the failure, which had now appeared on consecutive days.
The overall reliability record for Aston Martin and Honda during the recent American triple-header is alarming. Across the rounds in Austin, Mexico City and Brazil, the team’s two cars recorded five retirements from six possible race finishes.
Aston Martin chief trackside officer Mike Krack acknowledged that the team’s performance in Brazil offered some encouragement, but admitted that its reliability record remains a serious concern.
“We started from eighth position, but there was the incident with Bearman that cost us a couple of places; despite that, we never gave up,” Mike Krack explained.
“We made some good decisions, both when switching to wet tyres and when going back to intermediates towards the end. Unfortunately, we didn’t score any points and over the last triple-header we’ve had five retirements out of six possible results.”
“That’s an area we need to work extremely hard on: from a performance point of view there are positives, but from a reliability perspective considerably fewer. Nevertheless, we keep fighting.”
Honda admits it cannot identify cause of Aston Martin battery failures
The repeated technical failures have once again raised serious questions within Honda, reviving memories of the major engine vibration problems that repeatedly damaged battery packs during the opening stages of the 2026 season.
Those earlier difficulties were among the most significant technical problems encountered by the Japanese manufacturer following its partnership with Aston Martin. The Honda-powered team’s battery component usage had already become a major concern earlier in the championship, placing further pressure on the operation to improve reliability.
Shintaro Orihara, Honda’s general manager and chief trackside engineer, has now acknowledged that the manufacturer understands what happened to Lance Stroll’s car but has yet to establish precisely what triggered the failures.
“On Saturday we had a battery failure on Lance’s car and on Sunday the same problem happened again,” Shintaro Orihara explained.
“At the moment, we know what happened, but we don’t know what the root cause is. We’ll check the data and analyse the components; it could take a few weeks to get to the bottom of it.”
The Honda engineer also explained that the reliability improvements achieved around the middle of the season have not prevented further setbacks during the most recent Grands Prix.
“Reliability improved around the middle of the season, but over the last two or three races we’ve had several problems that weren’t related to mileage or excessive stress.”
“We absolutely have to find countermeasures for next year, otherwise we’ll continue to have the same issue.”
The admission is particularly concerning because the recurring failures are not simply being attributed to component wear or excessive usage. Honda must first identify the underlying cause before it can introduce an effective and lasting solution.
Honda warns of further problems ahead of 2027 F1 season
Beyond the battery failures, Shintaro Orihara also confirmed that the wet conditions at Interlagos had partially disguised the true extent of Honda’s performance deficit compared with rival power unit manufacturers.
Although Aston Martin demonstrated encouraging handling characteristics during the Brazilian Grand Prix, the reduced importance of outright engine power on a wet track made the overall package appear more competitive than it might have been in dry conditions.
“The wet conditions hide our deficits in pure power and the short duration of electrical deployment, shifting the focus towards driveability,” Shintaro Orihara explained.
“In some areas we saw encouraging signs, but we still have several problems to solve for the final part of the season and, above all, looking ahead to 2027.”
The warning underlines the scale of the challenge facing Aston Martin and Honda. While Fernando Alonso’s performance in Brazil demonstrated that the AMR26 can be competitive through corners, the team’s straight-line speed deficit and recurring battery failures continue to undermine its results.
With Honda still unable to identify the root cause of its latest reliability problems, the immediate priority is to understand why the failures have returned and develop measures to prevent them from recurring. Otherwise, the same weaknesses that have compromised Aston Martin’s 2026 campaign could remain an obstacle as the team prepares for the following season.
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