When Duracell filed suit against Energizer alleging that Energizer falsely claimed its “Energizer MAX lasts 10% longer than Duracell Power Boost,” the case seemed like just another round in the long-running rivalry between the Copper Top and the Energizer Bunny. But the lawsuit demonstrates that even the strongest brands in parity categories struggle to remain meaningfully different when the underlying technology is essentially the same.
The 10% That Sparked a Legal Charge
When Duracell filed suit against Energizer in June 2025, alleging that Energizer falsely claimed its “Energizer MAX lasts 10% longer than Duracell Power Boost,” the case seemed like just another round in the long-running rivalry between the Copper Top and the Energizer Bunny.
But the lawsuit demonstrates that even the strongest brands in parity categories struggle to remain meaningfully different when the underlying technology is essentially the same. (Duracell Inc. v. Energizer Brands, LLC, S.D.N.Y., filed June 16, 2025)
In batteries, there’s little room for technology to drive distinction. Alkaline is alkaline. Lithium is lithium. Both brands power the same flashlight, remote, and toy. Yet they must somehow convince consumers that one will keep going and going, just a bit longer. The fight isn’t really about a 10% performance edge. It’s about maintaining a brand edge.
The Brand Asset Rule: Difference Drives Value
The BrandAsset Valuator (BAV) framework, based on decades of tracking how consumers perceive thousands of brands, reveals a consistent truth: if your brand isn’t different in a way that matters, it can’t drive sales, margin, or growth.
Consumers always ask the same question: If I can’t see the difference, why should I pay the difference?
Battery brands face the same challenge as analgesics or bottled water. When every product performs about the same, perceived difference becomes the only fuel for premium pricing. The trouble comes when that difference is manufactured through claims the average consumer cannot verify or experience.
The Parity Trap: Selling What Consumers Can’t See
No one tests battery life side-by-side at home. Most consumers want confidence that their remote won’t die during the game or their flashlight won’t fade in a storm. A 10% advantage sounds precise, but it isn’t significant. It’s an engineer’s statistic dressed up as a marketer’s headline.
And yet, in a horse race between two iconic brands, even the illusion of victory matters. If one claims it lasts longer, it owns the “best” position in consumers’ minds. The other, whether or not the claim holds up, risks sliding into the same mental bucket as the store brand.
That’s the paradox of parity marketing: the harder you fight to prove a microscopic edge, the more you remind consumers that the products are basically the same.
When the Court of Law Meets the Court of Public Opinion
By the time this case winds its way through court, the legal outcome may not matter much. The real verdict will already have been delivered in the court of public opinion.
If Energizer’s claim is viewed as exaggerated, the Bunny’s bounce turns into a stumble. If Duracell looks defensive, the Copper Top loses its shine. Either way, the category’s credibility takes a hit, and private labels like Amazon Basics and Kirkland keep gaining ground.
For trademark and advertising attorneys, this is a reminder that brand law and brand strategy are inseparable. The Lanham Act may decide whether a 10% claim crosses the legal line, but the market decides whether it crosses the trust line.
Once consumers doubt the promise, even a legally defensible claim can damage long-term brand equity.
The Real Power Source: Trust
In categories where the technology is indistinguishable, the only lasting source of power is trust.
Brands can’t keep manufacturing differences with ever-smaller performance boasts. They must differentiate through experience, emotion, and consistency, things consumers can actually feel.
When the Bunny fights the Copper Top, it’s not just a battery war. It’s a warning.
What’s Happening to Batteries Is Happening Everywhere
The battery category isn’t unique. Look around and you’ll see the same dynamic playing out across industry after industry.
Smartphones now offer nearly identical features. Athletic wear performs about the same whether it’s Nike or private label. Even categories that once thrived on genuine innovation, like consumer electronics, are rapidly becoming commoditized.
As technology matures and production becomes democratized, meaningful product-based differentiation is disappearing. The microscopic edges that remain are increasingly invisible to consumers and irrelevant to their experience.
Innovative companies will recognize this shift and stop investing in marginal product claims no one can see or care about. Instead, they’ll build brands around what commodity products can never replicate: distinctive experiences, emotional connections, and hard-earned trust.
Because when you compete on claims no one can verify, you risk losing the only thing that matters: the belief that your brand is worth the premium.
This article originally appeared in Law.com.