More on batteries

I need to replace my batteries in my 1985 Ocean Alexander Aft cabin I almost never anchor out anymore and the boat is always connected to 110 volts except when I do on short day trips when at the dock I use AC power
My question is should I buy 2 staring batteries or 2 deep cycle ones
I was thinking about 2 group 31 starting batteries for both house and starting
All comment welcome

Ocean,

What is the largest size you can accommodate comfortably in the current battery box (compartment)

Oops, forgot to ask: single or twins?

What are your house loads? Do you operate an inverter underway for AC power? Generator?

With your requirements I think two Group 31 starting batteries will work fine. A single Group 31 at about 1000 CCA will start a Cummins 6BTA, a Yanmar 370/440, etc. If you have a bigger engine like a DD 6-71 you can parallel the two with the 1,2,all switch to start it/them.

David

I believe the current ones are 4d's the boat has twin 135 ford lehmans

AL
I don't use an inverter, the house loads are very small as I use AC power from the dock

Do you currently have a house bank and a starting bank?

Hi Blue
No the boat came with 2 4d deep cycle batteries that have been used for both house and starting

Let me expand a bit on my recommendation to install two Group 31 batteries:

If you do not anchor out overnight then you don't need a deep cycle "house" battery.

I will bet that your electrical system is wired to start one engine on one battery and the other engine on the other battery.

So without doing any rewiring, you need two start batteries.

Group 31 batteries have plenty of CCAs (about 1000) to start a Lehman 120/135 engine. They are about 2/3 of the weight of a 4D and us mere mortals can lift one in and out fairly easily. You probably will need two people to get the 4Ds out, or one husky football player type guy.

They will fit in the place where the 4D are and use exactly the same wiring. You might need new terminal ends if you currently have clamp on terminals because most 31s have screw on terminals.

You can buy them for about $100 ea at Sams Club or $125 at Batteries Plus.

David

If you have a battery connected to each engine, do you now how the DC loads on the boat are distributed? What does your battery switch say? Two group 31 batteries should be sufficient if you never intend on overnighting anywhere without AC power.

I'll assume each battery is dedicated to start each engine and each is available for house loads as selected on a 1-ALL-2-OFF switch. If you're just running between marinas and never need or want a large house battery to isolate your start capability from your house loads, I think 2 G31s will do fine. As stated above, each is capable of starting the engines.

If you don't have long-term or high demand house loads on at anchor (and I assume you have no generator), there's no need for a large house bank. Besides, once you build a large capacity house bank, a whole list of other requirements kick in like larger chargers and alternator(s), large cabling, generators/solar/wind power, an inverter to run all those new AC powered gadgets, etc. It's a long list of improvements needed to make a large house bank useful away from a dock.

And if you have the capability, you might as well add all kinds of new tricks and gadgets to make use of all that power like an extra fridge, ice makers, powerful air horns and washdown pumps, HDTV, Satellite TV, stereos with huge amplifiers, new lighting throughout, microwave, Keurig coffee maker, ...the list is endless!

Enjoy it with just 2 $100 batteries and consider yourself lucky!! You'll save yourself countless thousands!!

ocean said:

I need to replace my batteries in my 1985 Ocean Alexander Aft cabin I almost never anchor out anymore and the boat is always connected to 110 volts except when I do on short day trips when at the dock I use AC power
My question is should I buy 2 staring batteries or 2 deep cycle ones
I was thinking about 2 group 31 starting batteries for both house and starting
All comment welcome

Click to expand...

The group 31s will be just fine for what you do.

TRy Costco. I bought a group 27 deep cycle marine/RV battery last year for $89.00. You may have to special order a group 31, why not use group 27's?

Thanks all for your help I will go with 2x 31 group batteries I won't be enlarging my the capacity with more house power as at age 82 how many yrs are left
Long cruises are now just a memory
Bert

Hope you enjoy your many more short cruises as you continue to enjoy your boat, Bert!

Cheers!!

Just remember to match the batts to the service.

Start batts are poor and die with deep cycling from house loads.

Deep cycles need to be larger to start an engine due to reduced thick plate surface area.