How many 8D batteries

[eze2bme]

I have a 1979 43DC with 6-71Ns. There are two 8D batteries in each bank. Port bank for engine and genny. Starboard bank for engine and house panel. 1400 CCA each battery.
My question is: do you really need two 8D's to start an engine?
I use the boat year round here in South Carolina, temps are normally not that cold, and I have block heaters that keep the engine room at 65 degrees in the winter.
Would one 8D in each bank be sufficient to start the engine? I normally run the genny so very little load from the house 12v system.
Thanks.

 

[Boatsb]

1 should be enough to start it but if shes already set up for 2 each side why worry about it. It was designed by a group of smart people.

 

[rwappleton]

What Scott said! If you have some going bad Ken might be able to help you out. He does not work for Napa anymore but he still has some connections.

Hope all is well

 

[Timeout]

I had same setup and removed 1 battery on each side. Not only do they last longer now (I believe its because they don't beat each other up) but when I need to replace, there are only 2 instead of 4. Never had an issue with only 1 battery per side. So for me it saved money and actually worked better.

I may be adding a small inverter this year in anticipation of doing the loop. If so, I'll add the second Stb. battery back if I find I need it. Small inverter will only be for fridge and ice maker to avoid having to run the genny everytime I run the boat.

 

[fissioneng]

I had the same setup. When I needed to replace, I only put one in on the stbd side since it only starts the stbd engine and genny. Been that way for 7 years with no problems. (Deka on the stbd and Exide on the port side)

 

[eze2bme]

Thanks for the input. It's time to replace batteries again, only seem to last 3.5 to 4 years, so am thinking about using AGM batteries and only one per side. Lifeline model GPL-8DA marine battery with 1975 CCA @68 degrees. This battery is Mil-Spec rated, made in the USA and USCG approved. Same size as other 8D's and weighs 156 lbs.

 

[fissioneng]

It's time to replace batteries again, only seem to last 3.5 to 4 years, so am thinking about using AGM batteries and only one per side. Lifeline model GPL-8DA marine battery with 1975 CCA @68 degrees. This battery is Mil-Spec rated, made in the USA and USCG approved. Same size as other 8D's and weighs 156 lbs.

Sounds like you need a desulfator. My inexpensive Exide NG's are 7 years old and still have high SG. Did you check the specific gravity to determine this?

 

[Electric Easel]

I also had the same setup on my 42C the 4D's were rated at 1100 CCA and only installed 2 rated at
1800 CCA from NAPA and they work fine.

 

[Dan Mapes]

We have an '85 43' m/y that originally came with 2 on each side for the engines. Port was for the house and stbd for the genny etc..

I pulled the stbd cables to port and wrapped up the short pair of terminals. The longest pair just reached the terminals of the stbd most port side battery when it was spun the other way around. I used to the two batters on stbd to drive the inverter and house bank. I can use an alternator to charge them and the other battery should I wish to.

We took the boat South in 2008 from Kingston NYS like that, and over to the Bahamas 6 times going as far as Great Exuma. I never needed to parallel the batteries (that still works via the helm switch) except once when a yard let them die.

In Southern climates they spin right up. Even on cool 45 degree mornings.