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starting Marine and Boat Batteries

A 12V marine starting battery with high cold cranking amps is the best option if you need a powerful source to turn over your inboard or outboard motor.

Don’t know what size battery you need?

There are standardized battery group sizes for marine applications. Match up your dimensions to select the right BCI Group size.

Use this quick guide to match up your battery–approximate maximum dimensions.

Size Length Width Height
24M 10-1/4" 6-13/16" 9-3/4"
27M 12-1/2" 6-13/16" 9-3/4"
31M 13" 6-13/16" 9-7/16"
34M 10-1/4" 6-13/16" 7-7/8"
65 12-1/16" 7-9/16" 7-9/16"

Additional size may be available – Contact your local store for more information.

Tips to extend the life of your starting marine battery

  • Off-season battery maintenance will provide extended run time and lifetime for your marine battery.
  • Starting Marine and Boat batteries work best when the charge is maintained in the battery – do not store the battery in a discharged state. Use a top quality Marine Battery Charger
  • We even offer battery boxes, Rescue Packs and portable power for running accessories, and custom cables to make sure your boat battery is running at top speed

Should I use a Sealed or Flooded battery? Sealed batteries have high energy density, low internal resistance, and are maintenance free, spill proof. Flooded batteries are reliable, power sources with outstanding cost to power ratio. Some flooded batteries can be “watered”, if needed. Your application and maintenance plan will help in proper battery selection.


Batteries Plus Bulbs is also an industry leader for marine, boat deep cycle battery recycling. Each location is a drop-off point for battery recycling. Learn more about our recycling programs for consumers and businesses.

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