AGM batteries

devildogdad

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I have a 2012 Marlin, and I would like to use AGM batteries. Is there any problem with using these with the stock charger that comes with the Marlin ?
 

magicalbill

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Yes there is if your current Marlin charger doesn't have an "AGM" setting on it's panel that you can switch to.

I have a 2007 Gulstream that came with a Guest Charger. The batteries that came with the boat new lasted 8 years, no problems with either the charging system or the batteries.

When it came time to replace the batteries, my tech installed the AGM's and a few weeks later, the Guest charger went bad.

I suspect that the older 2007 Guest charger wasn't compatible with the AGM''s.
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Anyway, the new charger has an "AGM Setting" that I mentioned above.

Otherwise, the AGM's are great, just really heavy.
 

devildogdad

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thanks, I am now on my third set of batteries in a six year old boat. I keep getting a response from the mechanics that this is "normal" in Florida. I already spent almost $1000 to have someone go over the entire electric system and they found no fault.
 

magicalbill

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Your mechanics are likely referring to the extreme heat here and they say it takes an early toll on batteries.

I would agree, but keeping the batteries fully charged during periods your boat is not in use will prolong their life.

Your battery lifespan seems short to me. They should last at least 3-4 years, hopefully longer. Get your charging system together and run the charger whenever your Marlin stays at your dock/lift.

Hopefully there's nothing else contributing to your premature battery failure.
 

DennisG01

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2 years is too short. I don't boat in Florida, but I have a number of friends that do and if they would be a bit upset if they only got 3 or 4 years out of their wet cells. They typically average 5 or 6 years. They do, however, use their built-in smart charger all the time. Keeping your batteries on charge all the time is one of the best things you can do. Especially a charger that includes desulphation, which is one of the main reasons for early battery death (primarily a concern with flooded batteries).

Before you spend the money on AGM's, I would first get your charging system inspected/tested. There are tests you can do to check it's overall health - the tests could be in your manual or just call the manufacturer directly. Also in your manual should be whether it's able to charge AGM's, or not. However, AGM batteries are generally the same as flooded (although newer chargers will have a very slightly different charging program). It's "gel" batteries that are the big difference.
 

seasick

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Three things that speed up the battery aging are: High temps (yes, Florida is tough on batteries), over charging which can happen with a defective or not so smart charger or a bad alternator/regulator, and over discharging. The over discharging or too rapid a discharge rate can happen when the wrong type of battery is used for a task. For example, starting batteries are designed for high discharge rates for short periods of time and don't like to be discharged to a low voltage. House type batteries can handle reasonable discharge rates for extended periods of time and are generally OK being run all the way down but don't like high current draws like when starting.
High discharge rates can boil off a bit of the battery electrolyte and if the electrolyte gets too low a cell can be damaged. You may have undersized batteries for your typical loads. That is common when a lot of accessories have been added over time.
One more thing to check. Batteries that are run or charged together ( parallel wiring) should be the same type and age. Don't mix battery types
 

DennisG01

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Adding on to what Seasick mentioned... many wet cell batteries still require the checking/addition of water (distilled) once in a while. If your batteries are of that type, that could be the issue?
 

Doc Stressor

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The difference in the optimum charging profile between flooded cell and AGM batteries is miniscule. Chargers with an AGM setting will give a slightly better final charge level and some are able to charge deeply discharged AGMs that are not recognized by standard chargers. A smart charger with only a flooded cell setting while not harm AGMs. But it needs to be able to sense the charge level and taper the current appropriately, so it needs to be microprocessor controlled.

I have also had a lot of problems with AGM batteries in the Florida heat. I use them in my skiff because of access issues. I've never had one last more than 2 years and one even quit during the first year warranty period. These were Deka batteries sold under the West Marine label.

The problem is definately heat related. I've been able to extend the lifespan a bit by charging at no higher than 10 amps. They get very hot during fast charging when the outside temp is 95 degrees, even when using a smart charger with a temperature setting. The cause of failure is always the same -- a shorted cell that prevents the charger from starting up. I never had these problems when I lived out West in a cooler climate. I would always get 5-6 years out of my AGMs.

On the other hand, I've had great luck with the Deka 27m6 batteries that came stock with my Grady. I replaced them after 6 years with new ones even though the starting and house batteries still passed a load test just fine. They are dual purpose batteries that were specifically designed to meet the 182 min reserve capacity specifications for large Yamaha engines. While they are flooded cell, they are regenerative so that you hardly even need to add water.
 

everwhom

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For what it's worth, I was told I could not put AGM batteries without changing out my original 2003 Guest battery charger on my 330...
 

magicalbill

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everwhom;

Refer to my answer earlier in this thread; I had to replace my original Guest charger after I had AGM's installed.
 

Doc Stressor

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When it came time to replace the batteries, my tech installed the AGM's and a few weeks later, the Guest charger went bad.

I suspect that the older 2007 Guest charger wasn't compatible with the AGM''s.

It's easy to confuse correlation with causation. It is likely that your charger was going to fail anyway. AGMs will not damage a charger. It's the other way around. If you use a much older type of charger that doesn't sense the battery resistance, you can overcharge and damage AGM batteries.

Alternator/rectifiers are a different story. Because AGM batteries have a low internal impedance, they can accept much higher amperage from and alternator that might be rated at 50+ amps. While that doesn't typically damage the batteries, many alternators are not designed to operate at full output for sustained periods of time. That has been rumored to be the reason that Yamaha for many years would not recommend AGM batteries.
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magicalbill

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Doc;

You could very well be right, I'm just going by the timing of the failures. I thought it more than coincidental that my Guest Charger failed shortly after the AGM's were installed.
Remember, not a peep out of either the original charger or the batteries for 8 years until the batteries were replaced. When I saw the setting for AGM's on my new charger, I assumed that's what deep-sixed the Guest charger.

Anyway, I'm going on 2 years with the AGM's. No problems so far.
 

Doc Stressor

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What type of AGM batteries do you have Bill?

I'd like to try another brand in skiff and see if I have better luck.
 

magicalbill

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Just looked at the ticket..

Group # 27 it says.

Covers coming off the boat today; I'll look in the battery compartment to see if there's any other ID info.
 

magicalbill

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Doc:

Group 27M

930CCA

X2 Power.

That's all I could read leaning down into the battery area.
 

Doc Stressor

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X2 = Northstar -- very good but expensive batteries. They come with a 4 or 5 year full replacement warranty. But I don't think I'll got that route on my POS Carolina Skiff.
 

magicalbill

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No wonder they cost so much...

Great batteries, I agree.
 

SmokyMtnGrady

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I put AGMs in and use an external smart charge for them. My lifespan was no different than my flooded batteries. In the 226/228 the batteries sit together on the port side. The AGMs are much heavier. After my west Marine deka ones failed ,like Doc, I said forget it and. Just bought flooded deep cycle. The expense to me just did not warrant the return on investment in terms of longevity. I will say the AGM low internal discharge rate is great for the winter,but if you have an onboard charger then it really does not matter.