4D or 8D for starting a 6 cylinder John Deere

[Nick F]

I have to replace my starting battery and am wondering if a 4D would be more than adequate. (Current battery is an 8D) Engine is a 130HP John Deere naturally aspirated (John Deere 6404).

Thoughts, please.

 

[Comodave]

You could most likely get by with a Group 31. We had 4Ds on our last boat with SP225 Lehmans. Kept them just because of the builtin fiberglass battery boxes. Check out the required cranking amps for your engine and see if a 31 will meet those needs. Lot lighter…

 

[tiltrider1]

If you currently are set up for an 8d you will find two group 31's will fit very nicely and give you all the power you need for a lot less money.

 

[DC36Monk]

If you currently are set up for an 8d you will find two group 31's will fit very nicely and give you all the power you need for a lot less money.

True

 

[psneeld]

When I couldn't get a straight answer on my Lehman, I looked up the electrical requirements of the starter.

Turned out that a tiny group 24 met those requirements. I upsized one size to basically a group 27 so there would be reserve for lots of cranking/multiple short period starts.

That "size" worked great for probably 2000 engine hrs and 16000 miles of cruising....

There are so many designations and characteristics of batteries, sometimes thinking simply beats searching and searching for an answer that comes in too many confusing forms. Using what came in a boat can be really confusing as some boat batteries do double duty as house AND starting.

 

[Doodie99]

I have 2 group 27's in parallel on my Cat 3208 and it has as much power as the 8d and easier to lift.

 

[IRENE]

Jd4045

Our 4045 has a 4D. 2011-vintage planning by manufacturer for correct size.

This hull was the first to have this engine, so I suspect some consideration for appropriate CCA, etc.

 

[Nick F]

Good idea on the Group 31 - I had not thought of this. John Deere manual estimates 400 cranking amps at 70F, so well within a G31 which I was told has a CCA of 950A.

G31 is much easier to handle, too. Just have to find a couple of lumberjacks to lift out the old 8D. Or perhaps I will leave it where it is and strap the G31 close to it until I return to my home port.

Thanks for your inputs.

Nick

 

[Datenight]

I replaced an 8D with a single group 31 to crank a Perkins 6-354 in the green boat. Worked great.

Rob

 

[tiltrider1]

I replaced an 8D with a single group 31 to crank a Perkins 6-354 in the green boat. Worked great.

Rob

There is nothing wrong with replacing a single 8D with a single G31. A G31 uses much thinner plates than an 8D. This means it can produce the CCA needed, it also means the battery will produce the CCA for a shorter duration. This is usually not a problem. On the other hand two G31s double the duration that max CCA can be produced. Cells can and due go bad. If you have two batteries you have back up capability if you loose a cell.

 

[TowLou]

Most deers I have worked for example the powertec 6081 a grp 27 or a 31 will be enough if you do not need extended cranking times. If you want the extra cranking amps go with 2 grp 31's.

 

[koliver]

Though you ask as if you have only one engine, I thought you had a pair. I have to add, that my single 4D has done very well for all the time I have owned this boat and for at least some of the PO time, starting 2 6 cyl Volvos and a 3 cyl generator. If you can start each of your pair of Deeres with a gp 31, I am sure you can also start your generator from that same battery.
Many TF folk have redundancy after redundancy, especially where batteries are concerned. I doubt the wisdom of that, as all batteries have a life cycle, and the redundancy can be achieved with an interconnecting solenoid, making the house set available for the start and vice versa. That saves both $ and weight.

 

[Flatswing]

When I bought tiny DF 49 RPH, starting was either bank (or both) of 4x6v GC2’s in usual series/parallel configuration. After 6-7 yrs, starting needed both banks combined as they aged. I measured the starter amps at just under 600A for my JD 6068 225 HP. I rewired and replaced one bank as an isolated start bank with Deka G31 HD 1000 CCA FLA $150. Technically these are FLA, but basically no maintenance start batteries designed to start heavy equipment. Caps can be pried off to water if necessary. I only need 1 to start both 6068’s but have 3 in parallel as redundancy since they are the same size as my dinghy start battery and my generator start battery.

 

[GB42-424]

6404 with 4D's

I replaced my two 8D's with 4D's about 3 years ago. Works fine. Also removed the grand banks parallel solenoid that was wired to the start buttons and replaced with a remote battery switch from blue sea systems to parallel them if needed.

We must have close hull numbers.

 

[Wxx3]

You could most likely get by with a Group 31. We had 4Ds on our last boat with SP225 Lehmans. Kept them just because of the builtin fiberglass battery boxes. Check out the required cranking amps for your engine and see if a 31 will meet those needs. Lot lighter…

I did the same, a Grp 31. It worked for 7 days with never a problem on 6 cy Ford Lehman Sp135

 

[Nepidae]

I might ask, do you have a house bank of batteries and what are they?

IF you don't have a house bank but would use the 4D for double duty or consider building a house bank and an engine bank then you might want to consider your options there.

The short answer to your question is that yes, the 4D & 8D are very similar batteries and will handle the job, but if you are going to start replacing batteries you should look down the river as to what you want your boat for and how batteries will fit into that plan.

We went from a pair of 8D to a pair of 4D to a full house & engine bank with solar. Depends on how you see using your boat. We are on the Loop for the last 7yrs.

IF I can be of any help, let me know.

Good luck.

 

[LenBuchanan]

We replaced our 8D's on each of our Cummins 5.9 6 cyl 250hp with two Group 27's in parallel. We use Dual Purpose Marine Batteries from Batteries Plus. Our generator was a 4d and we replaced with a Group 31. This all on a recommendation from a Marine Electrician here in West Michigan.

Never had a problem yet and cruised all summer long last year up to Duluth, MN and back

 

[Nick F]

Thanks for all your inputs.

I replaced the dead 8D with a Group31 which is (obviously for a new battery) working fine. Based on its CCA rating (950A) I think it will do the job just fine, and free up space for other things.

To answer some questions posted - this boat (recently acquired) has 8 x golf cart batteries for house and another Gr31 for starting the generator. I have two engines - one starts off the house battery and the other off the new Gr31 (previously an 8D).

The alternator on the engine that starts with the Gr31 charges the house battery and vice-versa with the other engine.

Regards,
Nick