How many CCA's needed for a 3.0 Mercruiser?

[craze1cars]

I'm going to be buying a new battery soon for my 18 foot runabout, 3.0 Mercruiser. I run nothing more than a low powered radio and a depthfinder when shut down, and the motor is usually running so the alternator is charging most of the time anyway. So I figure a cranking battery is a better choice for me than a deep cycle. Do you agree or disagree?<br /><br />Also, I'm always looking for lighter weight so I want the smallest battery that can reliably start the boat. Is there a minimum CCA rating that's needed for this motor? I'm considering a dry cell ACM type marine battery, and I see some brands offer 34 to 38 pound 850 CCA batteries. Will this be sufficient or should I go bigger? Any advice is appreciated.

 

[Trent]

Re: How many CCA's needed for a 3.0 Mercruiser?

Min is 375 CCA. This is from the installation book on the 3.0

 

[tommays]

Re: How many CCA's needed for a 3.0 Mercruiser?

interstate and others MARKET a dual purpose battery that is some combo of both<br /><br />i would get the biggest one that will fit you really cant have to much battery<br /><br />i looked at the Optima and it would have to last a really really long time to pay off cause it was almost doubble the price of the battery that lasted 8 years<br /><br />tommays

 

[craze1cars]

Re: How many CCA's needed for a 3.0 Mercruiser?

Thanks for the spec, Trent. In hindsight I realized is misquoted my catalog...most of the small AGM batteries I see advertise about 850 MCA's, and 650 CCA's. Regardless, it sounds to me like any of these smaller AGMs could handle the job just fine if I only need 375. I'm not missing something here, am I?<br /><br />And thanks for your thoughts, Tommays. I currently have a lead acid dual purpose. It just seems unnecessary for me since I never deep cycle it at all. Money is really no big deal, they cost $99 to $149 dending on brand, so in my mind the extra $50ish above a conventional lead acid is well spent, considering it instantly removes 20 lbs out of the back of my underpowered boat, give longer life, better handling of off season storage, no acid, no gassing, no water maintenance, etc.<br /><br />Or am I just falling victim to their marketing ploys? Anyone else have a thought on this?<br /><br />Thanks to all!

 

[Dunaruna]

Re: How many CCA's needed for a 3.0 Mercruiser?

MCA specs will generally always be higher than CCA because CCA is measured at 0 deg(f), MCA is measured at 32 deg. The bigger the batt, the higher the cranking reserve - get the biggest one possible to suit your application. <br /><br />IMO get a'marine' battery. They are built better than auto, they handle vibrations much better.<br /><br />Aldo

 

[Boatist]

Re: How many CCA's needed for a 3.0 Mercruiser?

I would stick with what you got until you have trouble then get a group 24 or 26 lead acid.<br /><br />My last choice would be the optima. So many have tried them and I can not remember 1 person that liked them after a few months. How are yor going to adjust your charge voltage to keep battery happy? Just my opinion.<br /><br />Search this board for battery questions and read the threads.<br /><br />I also wonder why a 3.0L is not enough to push a 18 foot boat. I have a 3.0L on my 21 foot boat and it has plenty of power. Maybe it need a tune-up or the hull needs cleaned. Are you pulling two skiers and wanting 45 MPH?