Dell Australia spokesman Marty Filipowski questioned the 24-hour figure, saying HP had yet to articulate exactly how it achieved its results and what settings were used.
He noted that Dell's offering, unlike HP's, was on the market today and "our notebook travel weight seems to be lower than HP's".
Rego said whether users could achieve the maximum specified battery life depended largely on their usage habits.
"I think the point is not only about is it going to be 24 hours exactly, it's more like 'OK we're improving our battery life, we're delivering a longer lasting battery for you'," he said.
HP said it used the MobileMark 2007 application to test battery life, which uses scripts running on real business applications to try to simulate real-world usage. This is the same program Filipowski said Dell used for its testing.
(Update, 5pm: HP said it made an error in claiming it used MobileMark2007 to test the EliteBook 6930p. In fact, MobileMark 2005 was used, which uses Windows XP instead of Windows Vista. In MobileMark 2007 the laptop scored only 21.75 hours of battery life, HP said.)
But HP has yet to comment on the other settings it used to achieve the 24 hour figure, such as screen brightness.
Pitched at mobile professionals, the EliteBook 6930p weighs 2.1kg and features a 14.1-inch display. It will be priced from $1999.
IDC's market share figures for the second quarter of this year show HP is trouncing Dell in the laptop market. HP has 21 per cent of the market ahead of Toshiba (17.5 per cent), Acer (17.3 per cent) and Dell (15 per cent).
The competition is closer in the desktop market where HP leads on 23.5 per cent, followed by Dell (16.3 per cent) and Acer (10.1 per cent).