Adding A Second Battery Bank

[Door#3]

Yes, I'm posting yet another battery related thread :-)

My boat currently runs everything (starting and house) on a single bank of 2 8D batteries. The batteries are laid out port and stbd with room next to them to add another 8D next to each of them without too much trouble, other than muscling those heavy batteries into the area.

I was thinking of using the existing 8D's as the house batteries, and adding 2 more for the starting bank. What size batteries do I need for starting ? I want to be able to start on one of the two, keeping the second battery in reserve. Also would wire it so I could bring the house bank into play for starting if I had to.

I need to start a single Volvo D6 370...

I was hoping not to have to put 2 more 8D's in just for starting. Thoughts?

[RCook]

A pair of AGM starting batteries (wired in parallel) like Deka Intimidator, Sears Platinum (same as Odyssey), or Optima should do the job nicely, and weigh only about 80 lbs.

[sickcat]

You do not need 2 8Ds to crank a D6. One 8D is fine. Take a look at Odessy batteries. I have a friend who uses them for cranking batteries so he could add a bigger house bank. They pack a lot of cranking amps for there size and he has had them for 3 years now and they have held up well. He uses a battery not much bigger than a group 31 size to crank 871 detroits.

For a house bank I would go with 6volts in series. A lot easier to install except for a little extra wiring.