Mercury approves lithium-ion cranking batteries for all current outboard engines

Lithium-ion batteries have previously been restricted to house battery duties, catering to onboard electrical needs once the boat is at rest, while lead-acid batteries have handled the engines.

However, speaking at the launch of the new 350hp and 400hp Mercury V10 Verado, Mercury OEM sales director David Newcomb said lithium-ion could now be used for all electrical needs.

To ensure they are safe to use, though, there’s a catch – boat owners will need to buy the only starter battery approved to work with Mercury’s engines, and specifically those from Mercury-owned battery group RELiON.

“It's always been a no-no that outboards don't want you to use lithium-ion batteries to start and run them,” Newcomb said.

“But the public wants them,” he said. “It's more energy, less weight, more reliability. So for Mercury, it was only a few weeks ago approved for all their current generation engines to use the RELiON RB100-HP as a start battery.

“It's now that they have fully tested them with all their current-generation engines that they're saying okay, you can use them.”

Boaters are starting to favour lithium-ion batteries over traditional lead acid ones, mainly because they can weigh up to a third less than their traditional battery equivalents – a huge weight saving on a boat with multiple start and house batteries.

However, lithium-ion batteries need to be properly marinised to ensure they can’t short-circuit – an annoyance in a traditional battery system, but potentially catastrophic for the lithium-ion ones should they catch fire.

The RELiON batteries are available in both 12- and 24-volt formats.

It is not known if the RELiON start batteries will be offered in Australia. Mercury Australia was asked for comment.