Optima AGM Blue Top Marine Cranking Battery 800 CCA Group Size 34m

[GMLIII]

If anyone is looking to upgrade their existing lead acid battery with a AGM type battery here is what I know. I replaced my two Interstate group size 24 lead acid batteries with two Optima AGM batteries with group size 34m. For some reason these Optima batteries have a goofy sizing vs lead acid batteries. My lead acid batteries run about $128.00 retail vs the AGM Optima at $237 after core recovery and discounts from Advance Auto. The Optima size 34 M will fit into my existing battery box sized for a lead acid group size 24 battery. It is a bit lower in the battery case therefore I placed a 2 x 6 piece of wood in the bottom of the battery box to bring the terminal posts to the same height as the original battery in my 2017 G23. From what I have researched these AGM batteries hold their charge longer and the life of the battery is suppose to be longer than lead acid batteries. In addition they are suppose to preform better at cranking when the boat has been out of use for an extended period of time. This is a cranking AGM battery vs a deep cell type. Both the Interstate and the Optima have 800 CCA. I will report back later as to their performance and reliability.

[MLA]

Nothing weird about optima's group sizing at all. You swapped a 24 for a 34. Those group numbers have a direct correlation to the battery's physical size. They are supposed to be different. A group 34 is roughly 10L x 7W x 8H. A group 24 is right at an inch taller. Does not matter if its an AGM or LAWC.

[GMLIII]

Nothing weird about optima's group sizing at all. You swapped a 24 for a 34. Those group numbers have a direct correlation to the battery's physical size. They are supposed to be different. A group 34 is roughly 10L x 7W x 8H. A group 24 is right at an inch taller. Does not matter if its an AGM or LAWC.

Thanks for pointing that out. Bottomline I could not find a size 24 in AGM in Optima therefore I had to adjust my battery box to fit the size 34. The 2 x 6 piece of wood in the bottom brought the battery to the ideal height in the box.

In addtion MLA could you explain in my situation why a lower group size = a larger size battery. .

Optima AMG group size 34 M is smaller in size then the Interstate group size 24MS. Most folks would think just the opposite like me.

[SilentSeven]

What's the weight difference? For me, these are interesting as you can drop some lbs from the boat.

[GMLIII]

What's the weight difference? For me, these are interesting as you can drop some lbs from the boat.

Unfortunately not too much difference in weight although the 34M group size is 38.4 lbs for the Optima vs the Interstate group size 24MS at 44.6 lbs

[core-rider]

What is your use like? Are you only looking for starting batteries or do you want something that will run accessories while sitting with the engine off? From what I can tell you basically swapped for Optima's equivalent to the Interstate... both starting batteries. Those won't perform as well if you plan to sit with the engine off for extended periods of time like a deep cycle would, but also you went backwards with the Optima in Ah (amp hours) compared to the Interstate so you may notice more battery drain while sitting using accessories.

With a boat I say ALWAYS go deep cycle and as big as you can fit. Cold cranking amps doesn't play as much a role because you won't be using your boat at really cold temps most likely. In all you only gained the possibility of more mounting configurations with an AGM battery, but since you're using the factory location you won't even reap that benefit.

Not trying to burst your bubble, but more research and you could have saved some money for a better functioning battery IMHO.

[GMLIII]

All I did was replace 2 original 800 CCA lead batteries with 2 AGM 800 CCA batteries. Neither original batteries nor replacements were deep cell batteries. They may be pieces of crap but we will see. LOl

[MLA]

GMLIII

Optima does not offer a G-24 AGM, but Trojan and West Marine do.

The BCI (battery Council International) group numbers are for selecting the right size, in physical dimensions, for the application, They do not necessarily reflect any performance specs as compared to other group sizes with a higher or lower number. The BCI group numbers may be chronological as to what common sized where on the market when the BCI standards where implemented and what sizes came later in the industry.

Also, if your G has the factory on-board charger, you need to change the charge profile plug over to AGM. These will help them last. Even then, optima only recommends their charger for charging them.

[GMLIII]

GMLIII

Optima does not offer a G-24 AGM, but Trojan and West Marine do.

The BCI (battery Council International) group numbers are for selecting the right size, in physical dimensions, for the application, They do not necessarily reflect any performance specs as compared to other group sizes with a higher or lower number. The BCI group numbers may be chronological as to what common sized where on the market when the BCI standards where implemented and what sizes came later in the industry.

Also, if your G has the factory on-board charger, you need to change the charge profile plug over to AGM. These will help them last. Even then, optima only recommends their charger for charging them.

Thanks the NOCO onboard charger I purchased is compatible with AGM type batteries . Thanks again for your help

[bturner]

Ah AGM, brings out the angst in lead/acid battery lovers everywhere. No better sure fire way to get a thread moving that I know of. But what the heck I'll bite.....

This is what I know with a lot being from experience since I've actually owned a pair for quite some time.

AGM is not for everyone. And as BO said if you like your lead acid batteries, you can keep them. Or something like that.

AGM is more expensive. So what are some characteristics that might entice someone to spend that extra money.....

• The popular D34M (light grey case) is a dual purpose battery, performing well in both starting battery and in deep cycle applications. It's also probably the most popular AGM battery for our size boats.
• They are more resistant to vibrations which is good in a marine environment.
• As stated above they have many more mounting options. BTW ditch the plastic boxes and buy some nice mounting trays instead. (https://optimatrays.com/collections/optima-34-trays)
• They charge quicker (with the correct charger) and will charge more cycles. It's very important to have the correct charger for AGM batteries if you want the to last.
• They're spill proof and maintenance free. This sold me alone.
• If you take care of them they'll last a long time. I have one going on 8 seasons and the other going on 7.
• The performance doesn't degrade near as quickly over time as lead/acid batteries. This is due to the construction technique and materials used.
• They're smaller and lighter for "like" performance levels compared to lead/acid batteries.

What's not magic.....

• They'll hold a charge longer but still need to be charge maintained with the correct charger.
• You need the right charger for these batteries, grandpa's charger is no good here.
• Not for someone looking for a cheap battery, they're not.
• Not for someone looking for the largest battery, there are bigger.
• Not for someone not looking to change technologies. If none of the positive characteristics are attractive to you, you'll be unhappy with AGM. Batteries are something that no one pays attention to and are not seen unless something is wrong. For many this is a good reason to pass on AGM.

I've been personally been running AGM Blue Tops for going on 8 seasons. I had one fail at about 4 months. They replaced it, I still have both batteries and took them with me from my previous boat (I put new lead/acid batteries back in the boat before I sold it). That said I bought the Optima charger for the batteries when the first one failed as Optima sent me a discount code for the charger with the replacement certificate for the battery that failed. During the off season I bring my batteries in the basement and charge them once a month to keep them topped off. Past that they sit in the boat all season only getting charged when we take the boat out with the boat's charging circuit. All this seems to have worked out well for me. I added a picture of my last installation with the mounting plates here. I personally found this much better than the plastic boxes.

So are they right for you.... who knows. As I quoted BO at the start, if you like your lead/acid batteries you can keep them.

[MLA]

bturner

Are those bullet points yours or Optima's. I ask only because I would not apply Optima's marketing talking points to ALL AGM batteries. There are probably a dozen marine specific and non-marine AGM battery labels out there besides optima. Not all of those points apply to them. Some are the same battery just under a different label though. But still plenty of great AGM batteries to choose from.

In my experience, Optima is the last AGM I would suggest for a boater, especially if the application was for a house bank. For the $$$, the optimas has the lowest Ah rating for their group size, among other AGM.

[GMLIII]

Wow I created a monster on this thread. Very similar to asking what is the best "Cleaner" to use on your boat. LOL

[bturner]

Let the holy wars begin.

My comments were based on my personal ownership of Optima Blue Tops and in particular the D34M hybrid version. Deka (https://www.remybattery.com/batterie...batteries.html) and Odyssey (https://odysseybatteries.com/) are two other brands that I see most around here, both make fine batteries. I personally liked the mounting options for the Optima and they've worked well for me. With most other manufactures you're going to be stuck with the same mounting options as a lead/acid battery.

Look, I have no horse in this race. I don't own stock in Johnson Controls, I don't get paid for selling these and I'm certainly not an internet influencer looking for clicks. If you like something else please educate us by being more specific as to what they are are and why they're better. I'm always open to learning and hearing about a better solution especially if it'll save me money.

You say "in your experience" in your post. I guess my next question would be what was your experience? How many of these have you owned? What happened that turned you off them so hard? Just curious as your comments seem to be the kind that typically come up in these types of threads.

[scottb7]

Wow. Those trays are nice. I am cheap but those are very very tempting. My g21 came with optima's. (Maybe owner before me put them in)

In my 210 it was hard to get the batteries out with out tilting them and sometimes they spilled just a wee bit. So I really like that these agm are spill proof and maintenance free. It was pretty much a pain to add water to them.

I am a little confused about comment about "changing charge profile plug over" with on board chargers. "An OPTIMA battery is an AGM battery, not a gel battery or regular flooded battery." Manual says, "Your battery charger is equipped with a user programmable battery type selector that is factory set for standard Flooded (lead-acid) / AGM (Absorbed Glass Mat) batteries." So out of the box on my g21 it is fine with factory installed charger. On the upgraded prosports 20 i guess you get a high performance agm setting...see attachment.

I would add that if nautique really wanted to come across as premium they would go with a tray like this and ditch that piece of crap box, with the trash straps.

[bturner]

Wow I created a monster on this thread. Very similar to asking what is the best "Cleaner" to use on your boat. LOL

Yep. "My dad can beat up your dad" stuff in spades. A lot of times people haven't even owned an AGM battery and will come out swinging. Optima seems to be the true magnet for this though. I think it's sort of the "Frigidaire" of the marine AGM battery. Someone always knows someone that had a bad experience or maybe they've have a bad experience.

That's why I started with If you like your lead/acid battery, you can keep your lead/acid battery and by stating they're not for everyone.

Oh and I'm using Mobil 1 in my boat......