Starting Battery for 450 Cummins

[wpcv1776]

Hi everyone, especially those who have a 450 Cummins. What kind of starting battery do you have?

I have a 2004 31TE with a 450 hp Cummins diamond series. Right now we have a group 31 starting battery that's about 4 years old. It has always sounded like it's struggling to turn the engine, but then it's never failed to start. I've had people suggest that a group 8D would be more appropriate for that engine. I emailed Cummins and they were absolutely no help. Just curious what other folks are using. Spring is just around the corner

[addon323]

I have the same engine in my 2000 31TE and I have a 3 year old 8D battery. It works great and have never had an issue starting the engine. If your boat is wired the same as mine, you will want to shut the engine battery switch to off when either on the hook or at the dock without power. Otherwise your house will drain your starting battery. I learned that the hard way 30 miles offshore and now carry a jumper pack just in case. I do not have a genset but plan to install one soon. I keep my 8d house and 8d starting battery charged all winter. Hope this helps.

[Halcyon]

My boat came with an 8d for each of the 315 Yanmar’s. 31 sounds small for for 135 more hp.

[RobS]

We're talking a "dedicated" engine battery not shared for house loads, correct?

A healthy single Grp 31 can work but does not meet the 6CTA CCA spec. An 8D does but they are a real bear to deal with..

The 6CTA spec is 1,250 CCA's so go with a pair of Grp 31's in parallel and you will have more than the needed cranking power and batteries that are easy to handle.

For my twin 6BTA's one had an 8D and the other a 4D and I removed both and went with a single Grp 31 for each which meets the Cummins spec and never an issue. The Deka 1231PMF's at 1,000 CCA's meet the 6BTA CCA spec of 950 CCA.

6CTA Elec Specs and Deka Brochure attached.

[Pitou]

Hi everyone, especially those who have a 450 Cummins. What kind of starting battery do you have?

I have a 2004 31TE with a 450 hp Cummins diamond series. Right now we have a group 31 starting battery that's about 4 years old. It has always sounded like it's struggling to turn the engine, but then it's never failed to start. I've had people suggest that a group 8D would be more appropriate for that engine.

As Rob pointed out by posting the specs for your engine, a single Group 31 is very under sized for your engine. The suggestions that you've received for an 8D would be correct in giving the capacity needed, but why struggle and kill yourself handling these anchors?

My Cummins QSC 8.3 500 (490 bph) has the almost exact battery specs as you're 6CTA. My specs are 1250 CCA / 1563 MCA and was originally fitted with one Dual Purpose 130 lb. 8D @ 1425 CCA / 1730 MCA as the start battery. When it was time for a new battery, I refit, as Rob suggested, with a pair of Deka starting wet cell Group 31's in parallel at 57 lbs. each @ 1400 CCA and 1720 MCA in parallel. This arrangement is easily handled and no more broken backs. You'll thank yourself (or whoever does the job) when handling your start batteries in the future.

Start and Genset Banks.jpg

If still the original build set-up, I'll bet your house bank is an 8D Dual Purpose as well .. when the time comes consider refitting this bank with 4 - 6 volt golf cart batteries in parallel and in series. Same idea .. easier to handle and a true deep cycle house bank. I bumped my bank size to 6 - 6 volt golf carts.

House Bank.jpg

[wpcv1776]

Thanks for the info everybody. I think I have everything I need now. To answer a couple questions: yes it is a dedicated starting battery. It's a Odyssey 31m-pc2150 capacity 100 ah w/ 1150 cca. It's about 5 years old and has been worked pretty hard since we use our boat a lot. We have two group 8D's on house bank but as suggested will replace with golf cart or 31's when needed. Will probably take Robs advice for now and go with two 31's for starting. Not sure how I failed to find the spec sheet myself but I did look and even contacted Cummins.

Blue Skies!

[Pitou]

yes it is a dedicated starting battery. It's a Odyssey 31m-pc2150 capacity 100 ah w/ 1150 cca. It's about 5 years old and has been worked pretty hard since we use our boat a lot.
Blue Skies!

I was wondering how a Group 31 got your 6CTA started and now I know .. those Odyssey AGM's have significant more CCA than their wet cell cousins, but were still coming just a bit short on the specs.