8D battery replacement

I have a 40 Cabo with 700 Mans. It has two type 31's for starting, in series for 24v.
I also have four 31's for my house.
Much better than the 8D's I had in previous boats.

Sounds like the same set up for my 820 hp Mans. Buddy replaced each of his with 2, 4d's and my diesel mechanic suggested I do the same when the time comes.

I was going to suggest Odyssey batts too. They last longer and really pack a punch better than a regular AGM.

Lugging 8D's around, often lifting them up from a tender when at anchor, really messed my back up today.

Agree with "hire somebody" to do the grunt work.

Agree with Odyssey battery suggestions. (We got 11 and 12 seasons with a couple banks of those.) They do make some 8Ds now.

I'd also suggest comparison with Lifeline, another premium AGM battery maker, and ditto they make 8Ds.

Neither are inexpensive, but they've been worth it for us. AGMs also add the advantage of not having to water the things regularly, useful if the banks are in a difficult location.

-Chris

Again, I've been using 31 Series Odyssey for years. They're terrific batteries. 2 in series for each of my 24v main starters with a parallel, starting 12 cylinders each. Don't ever need the parallel if I've run the block heaters ahead of time...

I’m interested .
I have two standard wet cell 8Ds that 12 volt that power everything . Both Commercial NAPA 908D aka East Penn batteries. I get five years or so out of them. Mine are easy to get to and service. They use very little water, since I’ve upgraded to LED bulbs throughout the boat. This battery weighs 130lbs. $240.

But if I can get more life out of them along with a bit more punch , that’s a good thing .
So can I use the same battery charger I currently use ? It a Power mania 20 amp, modern charger. Maybe 4 years old.

I see NAPA has a Commercial AMG 8d 1450 CCA East Penn for $750. If you have AAA auto club , you get another 10% off. That’s still a bit pricey compared to a wet cell. This battery weighs 163 lbs.
why the weight difference ? From the other posts, AMG batteries should be lighter when comparing apples to apples? Where am I wrong ?

Our Lifeline 8D AGMs were about $750/each, IIRC. Something like 1350 CCA, 255-Ah, 156-lbs each.

I've not seen anything anywhere suggesting AGMs by definition should be lighter than flooded lead acid batteries. Might just depend on maker and model. I have read that heavier batteries might suggest better deep cycling capability, but that's probably just for very quick comparison... probably have to consult the respective makers' life cycle charts to get real comparison info.

-Chris

Chris thanks for the info. If I can get away from one less task to do on the boat, all the better. So I would never have to check or add water to them , if they are AMG. And use the same battery charger?

Lol…As we all know Old Cleanslate is a dummy some times…Yes I remember now back when I installed the charger , there is an adjustment thing on the top to switch to wet cell, AMG , and the other fancy battery, I forgot the name.
Thanks CR. Anyway I’ve got a motor to finish. No time or money to change up working batteries at the present time. But I will consider my options when these give out.

130 lbs ++ OH, my aching back.

Odyssey 31 Series gives you big cranking amps, smaller size and weight (78#), and last a long time.

https://www.odysseybattery.com/products/odx-agm31m-battery-31m-pc2150st/

My last purchase for these was to replace 2015 installs, 7 years later, and I used Amazon and had them delivered right to the boat.