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Old 10-09-2019, 03:18 AM   #8
catalinajack's Avatar
City: Edgewater, MD
Country: USA
Vessel Name: Catalina Jack
Vessel Model: Defever 44
Join Date: Nov 2011
Posts: 953
Our boat (twin Lehmans) has a house bank of eight golf car batteries, no separate starting battery. Those engines start in 1 or 2 seconds. I see no need for engine starting batteries in my case. However, I do have two Group 27s to start either of the two on board generators that could be used to start the engines in the highly unlikely event that the house bank was far too depleted. I once started the engines easily when I depleted the house bank to 20%. The two Group 27s for the generators is overkill. One would suffice. Charging is through a Blue Seas ACR.
Originally Posted by Dougcole View Post
My current setup:

Twin yanmar 4lha-stp, 240 hp.
Single 4D start battery, West Marine dual purpose, FLA (5 years old and dead)

House bank is 4 6V GC batteries, FLA (6 months old)
Banks are connected via an ACR. 50 amp shore power charger.

My start batt has recently bitten the dust and is no longer holding a charge. The 4D has worked pretty well, but they are sort of uncommon, expensive and heavy. Also, I'd like an actual start battery rather than a dual purpose. I looked but couldn't find a 4D start battery when I put this one in 5 years ago.

I'm not real happy with the longevity of this battery, it leads an easy life, not sure what caused such an early demise.

I'm considering going to a group 31 start battery. CCA are very similar, it's 1/2 the cost, easier to install and takes up less space. I reckon that if needed I could always get a second G31 and parallel it, cost of two would be about the same as one 4D.

Any thoughts? Any idea how many amps I need to crank my motors?

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