Battery Suggestion for penta 7.4GL

[flyhigh123]

I'm currently in the process of replacing 4 of the boats batteries.

The previous owner put Interstate 31-MHD battieries, which are heavy cycle, but not necessarily a marine deep cycle. Should I replace it with the same?

What is the suggest CCA for the 7.4GL system?

Can I use a 845 CCA marine deep cycle battery instead? Manual says 650 Minimum CCA, 165 reserve, however is that just for 1 battery? If I have 4 batteries can i use a batter with higher CCA but a lower reserve?



Also, car batteries have warranties up to 5 years, whereas marine is 1 year. Sounds like better to go with car battery which has the better warranty?

Thanks!

 

[alldodge]

That is a heavier battery but I would suggest and currently use group 27 marine starting bats for both my boats

Will say I prefer AGM's

 

[flyhigh123]

That is a heavier battery but I would suggest and currently use group 27 marine starting bats for both my boats

Will say I prefer AGM's

are you running one with 165 reserve? Is this number different if running multiple batteries?

 

[alldodge]

Reserve is for deep cycle in my books. I use Lifeline GPL-2700T for starting which are 1020 at 68F and 900 at 0F

Also use GPL-27T for house bats and has 186 discharge rate at 25 amps

I don't use any of the AGM cylinder bats, their junk

 

[wrench 3]

The marine batteries are built to take more of a pounding. If your using them as house batteries, you should be using deep cycles (or AGMs). I'm running one cranking battery on one bank and the equivalent of three 27 deep cycles on the other bank. But with four batteries I imagine that you have two batteries on each bank.
BTW a 4D takes up the same space as two 27s but has more capacity. The 4Ds have a reserve capacity of 390.

 

[flyhigh123]

yes my boat has 2 batteries for each bank, but when its run i think all 4 batteries go together into one 12v source which powers the rest of the boat. whether this is best practice or not, i'm not sure.

 

[wrench 3]

There should be a manual or automatic system to connect both banks together for charging when the engines are running. There should also be a manual control to allow you to run the boat off of only one bank at a time when at anchor.
This is the normal system. Mine is just a personal preference.

 

[bruceb58]

Since you have a GL, you don't have fuel injection so the type of battery(starting vs deep discharge) is not as much of an issue. I have the same engine and had always used marine deep discharge from Costco and never had an issue. I now use sears Platinum AGMs(rebranded Odyssey).

BTW, the deep discharge from Costco and Interstate are really more of a combo battery. A true deep discharge flooded acid is a Trojan type battery.

 

[flyhigh123]

I ended up getting the same ones from interstate, however I opted for their "Blems" unit which was a fraction of the cost. Ended up being $60 per battery, so 240 for the 4. Blems are their overstock batteries, brand new, that never sold. All less than 1 year old.