Duracell has been ordered to remove its "misleading" claim that its product lasts "up to 10 times longer" than ordinary zinc batteries.
"The claims to last 'up to 10 times longer' must be withdrawn," the Advertising Standards Authority (ASA) said in its ruling.
"The process to withdraw the claims and the advertising must be actioned with immediate effect on receipt of this ruling... The [ASA] is of the view that the claims and advertising in question communicates the claims in a misleading manner, rendering them misleading and in contravention...of the Code."
This follows a complaint lodged by competitor, Eveready Ltd, represented by Gerald Ramsden Attorneys.
The complainant contended that various 'protocols' referred to in Duracell's disclaimers were designed and implemented at the respondent's discretion, and do not stand up to scientific scrutiny.
The claim is used in various formats and advertising mediums.
Eveready submitted that in most instances, the advertising features a disclaimer explaining that the comparison is being made with "leading zinc carbon AA batteries" or "ordinary zinc carbon batteries" or that the tests were done relying on a particular 'protocol.
"In fact, the universally accepted standard test for such products is prescribed by the International Electrotechnical Commission (IEC). This standard ...has been adopted by the South African Bureau of Standards."
Eveready explained that when proper testing is done in accordance with SABS protocol, Duracell's product only lasts between 3,5 and 4,1 times longer than Eveready products (depending on which batteries are used).
"This is a far cry from the 10 times longer claim made, and shows that the respondent is relying on un-standardised testing protocols to exploit consumer-credulity and exaggerate the superiority of its products," Eveready submitted.
It further contended that tests done by the respondent in a digital camera do comply with the IEC/SABS standard. It said these were not applicable to zinc carbon batteries, and could not be used for the sake of comparison.
"As a result, the claim and advertising is unsubstantiated, dishonest, and likely to mislead consumers. In addition, it unjustifiably disparages a competitor product without having compared properly as required by the ASA Code."
Cliffe Dekker Hofmeyer Attorneys, on behalf of Duracell, argued that the respondent's claim of "10 times longer" was supported by documentary evidence and was pre-approved for publication by the ACA Advisory Service.
It explained that testing was done by Intertek Semko AB, a well-known global and independent Total Quality Assurance provider to industries worldwide, and the results showed that Duracell batteries outperformed Eveready Power plus silver size AA batteries.
It further submitted that the complainant's insistence on using the IEC/SABS methodology was misplaced, as the power consumption varies substantially by device used.
"It was for this reason that it decided to rely on tests conducted in specific toys and camera in order to obtain like-for-like comparisons," Cliffe Dekker Hofmeyer Attorneys said.
"The testing was done and the results verified by an independent and credible expert entity, and the advertising contains clear disclaimers regarding the methodology and results. Given this, and given that the advertising was pre-approved by the ACA, the complaint should be dismissed."
The respondent submitted confidential copies of its substantiating documents as well as signed correspondence from the ACA Advisory Services.