Best AGM start battery?

I didn’t have time to check my batteries before I left Florida, so Larry on Hobo introduced me to the marine electrician he trusts and uses. He checked out the Lifeline house bank and they all tested fine. However, he said the start battery failed the test. I’ve never really thought much about the start battery— it usually works fine. But lately I have had to “jump” it a couple of times using the house bank switch on my ignition panel, so I guess it makes sense it’s gone bad.

I know I want another AGM battery. The current start battery is something I bought at West Marine when on a trip a few years ago, and I don’t know the specs on it other than it being an AGM. What kind of start battery size do I need as far as CCA and whatnot? I want to keep it an AGM because the batteries are not easily accessible. My current house bank are Lifeline GPL-31XT, so I guess I need to keep the same basic size as those so it fits in the battery box.

I have a 110 HP Yanmar 4JH4-HTE main and a 3 cylinder yanmar-based generator.

A GP31 should start that smaller diesel easily.
I planning to switch to 2 Gp31s for a start / thruster bank.
I've been very happy with Sam's Club Duracell AGMs made in USA by East Penn. I've had 3 AGM 8Ds on the boat that have served me well but know I'm not installing any more 8Ds.
I just installed 8 Sams Club Duracell 6V AGM GC2s in our motorhome for a house bank (all electric MH with residential fridge)

I dont think you will find a more reasonable $/ AH or CCA option.

Bacchus said:

A GP31 should start that smaller diesel easily.
I planning to switch to 2 Gp31s for a start / thruster bank.
I've been very happy with Sam's Club Duracell AGMs made in USA by East Penn. I've had 3 AGM 8Ds on the boat that have served me well but know I'm not installing any more 8Ds.
I just installed 8 Sams Club Duracell 6V AGM GC2s in our motorhome for a house bank (all electric MH with residential fridge)

I dont think you will find a more reasonable $/ AH or CCA option.

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Awesome. Thanks.

Is this the one?

Not going to be the cheapest, but I'm a big fan of Optima red topped batteries. Their spiral wound design works extremely well in high vibration environments. Replaced my engine battery this winter on my John Deere 135 HP. It was 7 years old. Bought mine from Summit with free shipping.

https://www.summitracing.com/parts/ult-9004-003

I have them on the engine, generator, and 2 in series for my bow thruster (over 4 years old now).

Ted

I would definitely pay a little more for a battery that would last 7 years. Thanks.

Those Optima batteries are also smaller and not as heavy which is nice. That Duracell battery I posted is 69 lbs vs like 40 for the Optima.

That's the one.
I'm sure you can buy "better" or higher AH, CCA battys but like I said compare $/AH or $/CCA and I doubt you can do better.
My Duracell 8Ds are going on 8 yrs and still going strong. I check V after sitting uncharged in storage for 6 mos and consistently get 12.6 V before hooking up to top them off in the spring.
If you need to save wt check out Li but be ready to pay 5X what an AGM runs

You might also consider the Optima blue top model 34M. Different from the D34M blue top, which is a little more deep-cycle oriented.

It is starting-oriented, has more CCA than the red top, and has marine terminals as well as automotive-type posts. Weighs 38 lb. I had those for 7 years in my diesel Bounty, and they lasted ten years in my diesel truck.

The Duracell (East Penn) AGMs are good quality. West Marine house brand are the same thing.

What difference between an automotive start battery and a boat start battery? Both are intended to... start an engine.
I have a 7 years old agm from a big canadian retailer (not to name it but got tire in its name) and it has been flawless (and my old venerable oil burner is really not what I would call a small one and has been made before humans even discovered the wheel).
Size it properly for what you wanna start and that's it.

https://media.tenor.com/images/876b6b78d5e6f8adc5cacadac432c879/tenor.gif

L

Hey, just had a thought. If I have a good house bank I can parallel to when I need it, why do I need much of a start battery?

I used to be a fan of Optima....but since they went offshore for manufacture I elieve their quality has suffered....not an opinion....experience. Somenone mentioned weight. There is no free lunch wehn it comes to batteries. Generally speaking, the heavier the battery, the better. If you really want a good start battery and money is not objective, Odyssey or Lifeline is about as good as it gets. 75lb GRP 31 at 1150 CCA....there are no better. So bicker and whine all you want or pony up the cash...

cardude01 said:

Hey, just had a thought. If I have a good house bank I can parallel to when I need it, why do I need much of a start battery?

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Because when you wake up, after a wild night aboard, with all the lights on , as bright as a shining star and as loud as a train, with your head as heavy as the moon, the last thing you want is to be stuck in the middle of nowhere because your house bank is flat dead and you cannot startup your engine

L

Damn. Do you know me? ?

I use an Optima and had a bad experience too. Mine blew up. Kinda like a steam engine boiler bursting. Got a new Optima. They probably replaced it as I otherwise most likely would’a changed brands. Been quite a few years now and alls been well.

Of course having a start batt means your house and start batts are different. One thing should remain the same and that’s the recommended charging rate.

You already have one of the best AGMs, just add a set of twins to the family.

Odyssey has always seemed like the best in terms of performance, and the highest in price. I’ve never been a fan of Optima but haven’t personally had the bad experiences others have. East Penn seems to be a good compromise of quality and price, West Marine brand is made by them.
I will never buy another Lifeline battery. i’ve personally had them fail, had customers that have had them fail, and the company is horrible to work with if you have an issue.

Lou_tribal said:

What difference between an automotive start battery and a boat start battery? Both are intended to... start an engine....L

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The battery won`t know it`s in a boat unless you tell it. Difference may be solidity of construction. I figure a truck battery, like an 8D, should do the job. Check polarity, it may differ, bending and pulling cables to connect is not good.

You don't. The only starting batteries I have are for my generators. My Lehman 120s start from the house bank, eight golf car batteries. Engine start instantly. I do not lose sleep about inadvertently running down my house bank and not being able to start my engines. How often does that happen at anchor anyway? If it does, I can fire up the generator to recharge the house bank or just use my jumper cables. I could wire in a switch to use the generator starting batteries but that is way too much trouble to do for an extremely unlikely event that is easily overcome by other means.

The point is that, with many things boating, there are often several good ways to get the the finishing line.

cardude01 said:

Hey, just had a thought. If I have a good house bank I can parallel to when I need it, why do I need much of a start battery?

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I just realized my generator remote start panel doesn’t allow me to connect to the the house bank like the main engine start panel does, so I suppose I do need a fresh start battery.

I sure like the idea of the light weight of the Optima battery. The start battery is all the way in the back of the battery box, and I have to lug it hunched over in my cave like generator garage.

The engine manufacturer determines required cranking amps needed. It’s in the specs or owners manual somewhere. Could be CCA but just as likely MCA.

I’ve had good luck with Lifeline, seven plus years as a liveaboard and good luck with their customer service. They have start batteries in Groups 31, 27 and 24.

Personally, I like separate start batteries. It's more idiot-proof in terms of draining a battery, and it also keeps the electronics away from the voltage dip during engine start (concern for this varies with size of engine and house bank). So I'd keep a separate start battery whether you really need it or not. But if you can also start from the house bank, then I'm fine with the main and generator sharing a start battery.

Odyssey 31M-PC2150 Group 31 AGM for the main, and a 34M-PC3400 for the gennie. $$$$

We have two dual purpose banks. I installed switched our first bank of 3x crap to 3X PC2150s in Spring 2006, not replaced 'til mid-Summer 2017. The second set went in in Summer 2009, still in service. Huge cranking amps, very respectable cycle life.

Our PC1500 genset starter also went in in mid-Summer 2009, replaced this last February. Actually tested semi-OK but we were troubleshooting a genset starting problem, thought it might have been a battery thing... which turned out to be a battery switch thing... but by then we'd already replaced the earlier one.

Did I mention $$$$ ?

-Chris

My gen recently has a slow start issue, like it sounds like it’s cranking slowly, which always freaks me out since I read/heard that if it cranks too long it it could suck water in?

But the main starts quickly, so that’s weird. The main and gen use the same start battery.

cardude01 said:

My gen recently has a slow start issue, like it sounds like it’s cranking slowly, which always freaks me out since I read/heard that if it cranks too long it it could suck water in?

But the main starts quickly, so that’s weird. The main and gen use the same start battery.

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Could be a cabling issue, or it could just be more sensitive to a weak battery than the main.

The overcrank flooding thing depends on the engine in question and exhaust system design. I know my generator isn't susceptible to it, it'll push water out the exhaust while cranking and won't back-flood the engine. But the geometry of your system may not guarantee that, so unless you can confirm it, it's worth being careful.

ranger42c said:

Did I mention $$$$ ?

-Chris

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To me it sounds like $$$$ well spent. The "compromise" would be Deka/East Penn. If they last half that time(5-6 years), they still cost more than half. And many times, it is not about the cost. Listen to Cardude complain about having to replace his battery due to the location. So that could be a big deal in what you chose. Is the labor and back problems worth it? Yeah the Odysseys are heavy...and that is the reason they are so damn good.

I had the fortune of getting my Odysseys as Sears branded Die Hards for $250 a piece. Before buying them I called Odyssey and was impressed with how they handled my questions....mostly is it the same battery(yes)....and charging profiles. They were at the 7 year mark when I sold my last boat and they hadn't flinched yet!!!

Along the Odyssey lines, Northstar is generally pretty much equivalent. The X2 Power brand at Batteries Plus is a re-badged Northstar.

rslifkin said:

Along the Odyssey lines, Northstar is generally pretty much equivalent. The X2 Power brand at Batteries Plus is a re-badged Northstar.

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I have been wondering about those batteries. I even wondered if they were rebadged Odysseys since their specs are almost exact...I even saw one labeled as a PC2150 or something like that....similar to how Odyssey names their batteries. I will check into your X2. I am likely getting close to redoing my electrical system.

Edit....I did look. There appears to be basically no price difference between the two. It does appear they offer a 4 year versus a 3 year full replacement warranty....so I guess there is value in that. Also, would you prefer batteries plus storefront support or West Marine?....Curious what that battery would cost on Port Supply...

I too am going to be following this tread. Looking to replace the entire house bank w/ lower maintenance AGMs. Right now six T-105s, they're starting to get thirsty. Thinking I'd like to be ahead of the curve and make sure to have a plan. Was going to replace with Lifeline but now having second thoughts.

bshillam said:

I too am going to be following this tread. Looking to replace the entire house bank w/ lower maintenance AGMs. Right now six T-105s, they're starting to get thirsty. Thinking I'd like to be ahead of the curve and make sure to have a plan. Was going to replace with Lifeline but now having second thoughts.

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One of our main dual-purpose banks is now 4x Lifeline GPL-4CT AGMs, same size as T-105s. But we've only had them since May 2017, so can't tell longevity yet.

If you have additional height, the 6CTs would give you even more capacity...

-Chris

"What difference between an automotive start battery and a boat start battery? Both are intended to... start an engine."

Usually the only difference is the BS "MCA" rating.

CCA is at a low temperature , MCA is at a higher temperature so it makes a crap battery look better.

Only use CCA for batt comparison as that is what the engine mfg or marinizer will specify.