3208 start batteries

[ORIF]

Can I get suggestions on alternative battery to 8Ds for my twin 3208 NAs?

If information on my starter is needed for this I can probably figure out what they are.

I currently have a dedicated 8D for each engine and a single 8D for house.

So 3 8Ds on my battery shelf in the engine room which after 35 years of supporting 400 lbs I either need to rebuild or shore up.

I´ve tried searches of past forums and answers seem varied.

Only consensus I can find is that everyone agrees that 8Ds are heavy but effective.

For alternatives I´m seeing some say a single group 31 and others saying it takes 2 in parallel to start these engines.

Is it feasible to have one battery set for both engines? That would substantially improve the weight issue.

I´ve read that not enough battery can burn up the starter but I´m not sure I understand why? Starter has to pull more amps?

Some say 2 6V golf cart batteries in series are acceptable and others say they are better suited for house than start batteries.

Can I get suggestions on what the wisdom on this site thinks may be the best alternative to heavy 8Ds to start 3208 NAs?

Thanks

Edward

 

[Portage_Bay]

I use a single 8D for twin 3208 NAs without problems. I do have a substantial house bank that can be used as backup starting. As well as a generator start battery that should get the 3208's going. Under normal circumstances 3208s start very easily.

When the aging 8D shows signs of getting weak I will probably replace it with two group 31 batts in parallel. 8Ds are more than my back wants to handle anymore.

 

[ORIF]

I use a single 8D for twin 3208 NAs without problems. I do have a substantial house bank that can be used as backup starting. As well as a generator start battery that should get the 3208's going. Under normal circumstances 3208s start very easily.

When the aging 8D shows signs of getting weak I will probably replace it with two group 31 batts in parallel. 8Ds are more than my back wants to handle anymore.

PB, Thanks - what does your house bank consist of?

 

[DavidM]

The 3208 is a 10+ liter engine. I know that a single G31 works fine with an 8.3 liter Cummins but I think that the bigger Cat needs a 4D, 8D or two G31s in series if lifting the beast of an 8D is a problem.

You could rewire things to use a single 8D for starting both engines and then set up your house battery bank with real deep cycle golf cart batteries. These give the most bang for the buck for deep cycle house use.

David

 

[Alaskan Sea-Duction]

Hi Ed. I have 3208TA on ASD. Each engine had its own 8D start battery. I junked them several years ago and replaced with two Group 31 HD truck maintenance free batteries. Very happy.

 

[ranger58sb]

Orif, your Cat 3208 spec sheet will tell you the minimum required cranking amps for your engines.

Probably a pair of G31s will do it, but if that's on the edge of minimum, Odyssey PC-2150s (G31 AGMs) wouldn't be a bad choice... since they seem to be designed to deliver more cranking amps than many of the other typical G31s.

-Chris

 

[ORIF]

Hi Ed. I have 3208TA on ASD. Each engine had its own 8D start battery. I junked them several years ago and replaced with two Group 31 HD truck maintenance free batteries. Very happy.

Sea-Duction, are your G31's in parallel to both engines or 1 battery to each engine separately?

Curious because as David M points out, I'm trying to figure out if 1 G31 is enough to start off a 3208.

Thanks,
Edward

 

[Alabama Boater]

I am currently using a single group 31 starting battery for my 435hp 3208s on each engine. They are the HD Duracell version, slightly over 1000 cranking amps. My start panel allows for push button combining if needed. The port battery also serves as my gen start but I can auto connect to my house bank ( 4 GC in parallel/series) through 300amp Blue Seas battery combiner. Living south of most extreme temperature range and using block heaters have allowed boat use down to the high 20s when traveling several years ago. My engines start with a few turns even after sitting a month or more.

 

[Comodave]

I would use 2 Group 31s in parallel for starting both engines. Then put in 4 6 volt golf cart batteries in series/parallel for the house bank if you want to stay with all flooded batteries. Have a battery switch so you can start off the house bank if the start batteries give you a problem. You will still be about the same weight as 3 8Ds but they will be much easier on your back. Just rebuild your battery shelf stoutly.

 

[rslifkin]

2x g31 should be plenty to start the things. I'd personally run a start bank for each engine and ditch the gen start bank. Just install a switch to allow the gen to use either engine start bank and you've got 2 good starting sources for each item separate from the house.

 

[Portage_Bay]

PB, Thanks - what does your house bank consist of?

The house bank is six 6 volt deep cycle golf car batteries in series / parallel.

 

[tiltrider1]

I currently use two 8D batteries in parallel to start both engines. I have 8 L16 batteries for my house bank. Now I will be the first to tell you, this is more than necessary in all cases but I never have battery issues.

That said, I would rather see two group 31's in parallel used to start both engines than a single group 31 dedicated to each engine. I would rather not see GC or L16 batteries used as start batteries except in emergencies.

When my 8d's give up the ghost I will probably replace them with 4 group 31's in parallel. I have the room so I am sticking with the excessive capacity.

Now in your case I think you should replace one of your 8d's with two group 31's in parallel set up to start both engines. Then I would use the remaining space for GC or L16 batteries for your house bank. I think you are over kill on your start capacity and under on your house. However, this really depends on how you use your boat. I know some boats that turn the generator on first then start the engines, at the end of the day they turn off the engines but only turn off the generator if on shore power. In this case I would stick to the set up that you currently have.

 

[Alaskan Sea-Duction]

I would use 2 Group 31s in parallel for starting both engines. Then put in 4 6 volt golf cart batteries in series/parallel for the house bank if you want to stay with all flooded batteries. Have a battery switch so you can start off the house bank if the start batteries give you a problem. You will still be about the same weight as 3 8Ds but they will be much easier on your back. Just rebuild your battery shelf stoutly.

What he said

Look at any truck. If it has a diesel it has 2 batteries. Why are some folks insisting you have to have 8D in a marine application?

 

[Portage_Bay]

Why are some folks insisting you have to have 8D in a marine application?

Cause that's the way it usta always be. But when I move the aging 8D out at the end of it's life I'm done with 'em.

 

[Ski in NC]

Two grp 31's will do fine. In fact, a single grp 31 will do it, but nice to have a little margin.

 

[FF]

"I´m seeing some say a single group 31 and others saying it takes 2 in parallel to start these engines."


The difference might be in how cold the engine is before starting. Under freezing conditions the second Gp 31 will help spin the engine faster which makes for easier starting.

 

[Bacchus]

Edward
My Mainship had 3 AGM 8Ds configured 2 combo house / single eng start and a 3rd dedicated thruster 8D.
I moved my start to the thruster bank in anticipation of changing put the 8Ds to something else. Looking at specs a pair of GP31s are pretty close to equal 1 8D for CCA / MCA and a pair of 6V GCs close to a 8D for AH.
My plan was possibly 2 GP31s for start / thruster and 4 GCs for house.
That is what I would do if going w/ FLA. What I found out from East Penn & Trojan was that with AGMs they perform equally well for both start & deep cycle as they do not have different plate designs like FLAs do.
I'm now thinking when replacement time comes to just go with 6 GP31s and be uniform for everything.
In your case, if you don't have a combine switch to provide use of house to start or supplement the start bank I would add it just for insurance. I see no reason to have separate start battys but some may keep them to provide a back up.

 

[Seevee]

Agree with the two Group 31s. And you could use one set to start either engine. And the backup switch to the house would be a great idea.

 

[tiltrider1]

Some are going to say 1 group 31 and others are going to say 2 in parallel. The reason is that one will do the job but it doesn’t really meet the specs. So if you are a minimalist then you go for 1. If you are conservative you go for 2. If you have space and extra money you go for 4.

 

[ghost]

For unplanned reasons I wound up with a single group 31 starting both of my 3208’s. It worked, but at the three year mark, was getting pretty tired. After finally rearranging my battery boxes, I now have two 31’s in parallel, which was the original plan. Absolutely no problem whatsoever with that configuration.

One will work, for years, because 3208’s start sooooo easily, but two in parallel is a better idea.

 

[DennisB1]

I am using a single Northstar AGM 215 amp battery to start both 3208TAs. The house bank is 5 Northstar 215 amp batteries. The generators start off the house bank or with a back up group 24 agm thru a 3 way switch. The gen sets are 8kw units.
I installed a new starter recently, The starting current ranges from 600 to 1600 amps depending upon the delivered voltage at the starter motor per the spec sheet with the starter motor. Typically it would be in the 1000 amp range with a cold engine when the engine requires some more amps during the start. Typical cranking time is maybe 2 or 3 seconds before engine start.