2005 Mercruiser 5.0 MPI w/ Bravo 3 Batteries

[OllieC]

s/n 0W037286

I currently have a factory dual battery setup. The batteries I currently have installed are Interstates 27M. Here are the Specs;

27M CCA=600 MCA=750 RC(Min)25a=160 hrs at ampr load-5=17, 15=5.2, 25=3.6

I would like to upgrade to the Interstate 29M because of the increased Amp Hrs. I've installed a new sound system. Here's the spec;

29M CCA=675 MCA=845 RC(Min)25a=210 hrs at ampr load-5=21, 15=6.4, 25=3.4


My concern is if I upgrade, will I screw something up electronically or mess up my starter? It doesn't seem like the CCA is that much different or will harm anything - again, I'm just looking to gain amp hours.

Thanks,
Ollie

 

[Don S]

Re: 2005 Mercruiser 5.0 MPI w/ Bravo 3 Batteries

Won't hurt anything to go with a larger battery.

 

[OllieC]

Re: 2005 Mercruiser 5.0 MPI w/ Bravo 3 Batteries

Thanks Don - I was hoping to get a reply from you.

 

[Fun Times]

Re: 2005 Mercruiser 5.0 MPI w/ Bravo 3 Batteries

Just so you are aware, If you plan on using these batteries for both starting the engine + run a bigger sound system then technically speaking the batteries you have now and the batteries you plan on getting are both underrated to use on the engine model you have according to mercruisers recommendations,

Minimum battery rating
(Non‑DTS models) 750 CCA, 950 MCA, or 180 Ah
Minimum battery rating
(DTS models) 800 CCA, 1000 MCA, or 190 Ah

 

[KD4UPL]

Re: 2005 Mercruiser 5.0 MPI w/ Bravo 3 Batteries

Why stop at a group 29? Might as well get a group 31. They're a little more common and have basically the same footprint. Put as big a battery in as you can afford/fit. It won't matter to your starter motor or anything else.

 

[thumpar]

Re: 2005 Mercruiser 5.0 MPI w/ Bravo 3 Batteries

How are they hooked up? My system is smaller but when I went to add a battery I put in an isolator. I have one battery that is only for starting and running the engine and trim for minimal requirements. The other is for everything else. If I put in a big sound system I could get a 3 battery isolator so that the sound runs off one of the batteries separately. The isolator will makes sure you have power in the starting battery even if you drain the other(s).

 

[OllieC]

Re: 2005 Mercruiser 5.0 MPI w/ Bravo 3 Batteries

My plan is to run the 400w amp directly to the house battery. I figure when the boat isn't running, my max draw would be 25amps (which I assume would be too loud most of the time anyway). The amp has a 40 amp fuse block. So, it'll mainly be louder under way which is moot as far as draw.
We may do a couple over nighters on the Apostle Islands, so I'll obviously need my all-around light.

I'll reserve batt 1 for starting.
If that doesn't work - I have my reserve power pack.

Thanks,
Ollie