By Jonathan Stempel
NEW YORK (Reuters) - Duracell, the battery unit of Warren Buffett's Berkshire Hathaway Inc (N:BRKa), sued the maker of Energizer batteries on Tuesday, accusing it falsely advertising that its Energizer MAX batteries last up to 50% longer than other alkaline batteries.
The lawsuit follows Energizer Holdings Inc's (N:ENR) own lawsuit last Sept. 30 accusing Duracell of falsely advertising that its then-new "Optimum" batteries were more powerful and lasted longer than rival batteries.
Duracell filed counterclaims alleging false advertising in that case. It is now accusing Energizer of having "doubled down" by claiming on battery packages, on printed coupons and through in-store advertising that MAX batteries are "up to 50% longer lasting than basic alkaline in demanding devices."
Energizer is attempting "to confuse and mislead consumers regarding the comparative benefits of Energizer's MAX batteries relative to other alkaline batteries," including Duracell's Coppertop batteries, Duracell's complaint said.
Lawyers for Energizer did not immediately respond to requests for comment.
Both lawsuits were filed in Manhattan federal court.
The companies have sought damages for false advertising under New York law and the federal Lanham Act, as well as halts to any improper advertising.
Duracell said it had a 45% share of the U.S. market for alkaline household batteries, while Energizer has a 26% share.
Berkshire bought Duracell, which has offices in Bethel, Connecticut, from Procter & Gamble Co (N:PG) in February 2016. Energizer is based in St. Louis.
The latest case is Duracell US Operations Inc v Energizer Brands LLC, U.S. District Court, Southern District of New York, No. 20-07318.