Moderated Discussion Areas
  ContinuousWave: Small Boat Electrical
  OptiMax 225-HP: Starting Battery

Post New Topic  Post Reply
search | FAQ | profile | register | author help

Author Topic:   OptiMax 225-HP: Starting Battery
BIG O posted 03-21-2006 07:43 AM ET (US)   Profile for BIG O   Send Email to BIG O  
I have a 1999 Outrage 26 with twin 225 Optimax, which I bought in November I know the batteries are not original on this boat because they are actually smaler than the tray. What is the correct size battery? What is a good brand? What is the recommended current capacity of a battery for use with a Mercury OptiMax 225-HP motor?
Thank you in advance for any advice
Big O
jimh posted 03-21-2006 09:20 AM ET (US)     Profile for jimh  Send Email to jimh     
Typically a new Boston Whaler boat delivered to a customer will have the batteries installed by the dealer who delivers it. There may be some variation among boats as to the size and capacity of the batteries, depending on what the dealer or later the owner installed. Thus it is hard to predict exactly what size the battery enclosure on your particular boat might be.

Batteries are rated by size by a confusing series of numbers. The most common size is a Group-24. Group-27 and Group-31 are also common; they are slightly larger.

For more information on Battery Size, see:

Most marine batteries are in the Group 24 size or slightly larger. Batteries that are physically larger generally have larger Ampere-Hour ratings (A-h). The A-h rating is a measure of the ability of the battery to store and provide electrical energy over a period of time.

The battery requirements of the Mercury OptiMax engine will be mentioned in the owner's manual. In general, the OptiMax is a engine that uses a lot of electrical energy to initially start and run, so it needs a very strong battery. Voltage sags during start-up can cause problems. For this reason, I believe you will find a recommendation of a battery whose current capacity is rated at a minimum of 1,000 Marine Cranking Amps (MCA). The MCA rating of a battery determines how much current it can provide under a heavy load like starting an engine. This assumes the battery is fully charged. You can obtain a battery with a 1,000-MCA rating in many different physical sizes and A-h ratings.

BIG O posted 03-21-2006 09:32 AM ET (US)     Profile for BIG O  Send Email to BIG O     
Great info thanks Jim
jimh posted 03-21-2006 09:33 AM ET (US)     Profile for jimh  Send Email to jimh     
Once you have selected a particular physical size, a particular Ampere-hour rating, and a battery with a minimum of 1,000-MCA cranking current, you will then have to decide what type of battery you wish to use. The choices are many, but briefly there are:

--wet cell lead/acid
--Absorbed Glass Mat, or Absorptive Glass Micro-Fibre, or AGM
--Gel Cells

For decades the standard wet cell lead/acid battery has served well in marine applications, but recently some mariners have switched to using AGM batteries. AGM batteries generally are sealed and will not spill. They are also thought to be better for harsh vibration environments like a small boat.

You can choose almost any price point in a battery. Many use inexpensive batteries from discount retailers like WALMART and replace them at regular intervals (such as every three years), while others buy more expensive batteries and expect longer life spans from them (like ten years).

I do not have any authoritative data of my own on batteries, but instead rely on the work of others, such as POWERBOAT REPORT magazine. They just published the results of their independent testing of about a dozen batteries of various types and manufacturer. I would be guided by their results.

rtk posted 03-21-2006 10:46 AM ET (US)     Profile for rtk  Send Email to rtk has their brand of AGM batteries on sale now. A group 24 is around $115, and the MCA and CCA ratings are well in excess of the 1000 MCA required of the Optimax.

Do a search on their site, or look under the boating catagory.

I have read very good reports on the Cabelas AGM batteries.

AGM batteries make so much sense for a small boat, epecially if they get banged around a bit in poor conditions.


Post New Topic  Post Reply
Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.