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AGM batteries: Someone using them?

13K views 82 replies 23 participants last post by  Jgbrown 
#1 · (Edited)
AGM batteries have a big defect, they are expensive but have many advantages and mainly two that make them very interesting for cruisers:

1 – They lose very little charge so they can be let alone with minimum maintenance if you don’t use the boat in the winter.

2 – And main advantage, they charge 3 times faster than normal batteries.

Providing you have a big enough alternator this means that you have to run the engine for 3 times less hours (for charging) than with regular batteries. This is a huge advantage and will make them not expensive at all because the running hours of the engine are expensive. Of course the main advantage is that you gain a much bigger electric autonomy on your boat.

Well, this is what I have read and it is consensual but I would like to know if someone is using them and if this works out like that in reality, meaning if there really are a big difference in charging time?

..
 
#3 ·
If you don't like running your engine to charge your batteries, the fast charge thing is huge. In the Sea of Cortez and Banderas Bay, where it is almost always cloud free, you can keep them charged just with solar panels, even running refrigeration and making ice, nav gear, lights, stereo, water makers, etc.

Their initial and replacement cost is horrible if you are retired and cruising. One of my pals is trying to figure out where he is going to come up with $6k for a new AGM battery bank.....

Ian
 
#4 ·
....

Their initial and replacement cost is horrible if you are retired and cruising. One of my pals is trying to figure out where he is going to come up with $6k for a new AGM battery bank.....

Ian
That should be a huge bank of batteries. For what I have heard they cost about 3 times more than regular batteries.

Regards

Paulo
 
#7 ·
Paulo,

I never had lead acid or lead. When I bought my boat, and studied a bit, aside from cost, AGM was a no brainer. They lasted four years, and my use was very irregular. Last year, I upsized my battery bank to (7) 105Ah battery bank, AGM. I run a 10,000BTU air conditioner with it. Love it, no genset. Turns out that my engine is quieter than my single-cylinder genset too. Another advantage is that AGMs are sealed, zero maintenance and zero gas emmissions from what I have read. Good AGM bank and large alternator. More than enough for your refrigeration. Do the numbers. Good luck!
 
#9 · (Edited)
AGM IS.......lead acid......... They can also vent gas if over charged, and when they do, the lost electrolyte can not be replaced.

If your bank of AGM batteries is made by Lifeline they are not maintenance free and need to be equalized occasionally, or as Lifeline calls it "conditioned", at 15.5V temp compensated for about 8 hours, especially if you are a cruiser.

My experiences with AGM, to summarize, are that:

They cost a lot more
Have shorter cycle life
Accept more current than wet lead acid
When they fail they tend to fail with little to no warning
Need to be charged to 100% SOC as often as possible

My experiences & thoughts.....

AGM's Making The Choice (LINK)
 
#11 ·
I have 6 -6 volt Lifeline AGM. 720 ah. I do "equalize or condition as Maine sail recommended. Also based on his recommendation I outfitted with an Electromax 120 with serp belt and Maxx regulator with appropruiate temp sensor. Important with the large battery bank to charge to not run the alternator at such a hig charge to get to 85% for a long time. If you go the large amp hr route make sure you also upgrade the alternor or you will burn it out.

Lifeline AGM supposed can be charged over 1000 cycle I am going on 4 years now with mine with never a problem. Also check the arrenty. I know its par rated by some is better than 0

My advantages.-
6 volts easier to pick up than 8D.
No maintainence except equalizing- and they are in a tough sopt n the boat to get to
They can be stacked on their sides or many configuations
Somne of them (Kifeline) mastervolt have low profiles
Accept a charge more quickly

Price the Lifelines many places as the prices really vary greatly. Some have free shipping. You can by many 6 volt cheaper,,,for sure,,,but the time for maintainence and such may not be worth it for you.

Dave
 
#26 ·
I have 6 -6 volt Lifeline AGM. 720 ah. ...

My advantages.-
6 volts easier to pick up than 8D.
...
Price the Lifelines many places as the prices really vary greatly. Some have free shipping. You can by many 6 volt cheaper,,,for sure,,,but the time for maintainence and such may not be worth it for you.
...
I would look at getting at least 4- 6 volt lifelines. Thats 440 or 480 depending on the ones you buy. The footprint space of the 4 6 volt will take up the room of less than 3 group 31. 3 group 31 is about 330 ah. Also you do not need battery boxes for the AGM just have to secure them although i did have the space for battery boxes. If you can get 6 in the space. I made dummies out of cardboard of the batteries and fit them into the compartment uinder my rear quarter berth to see the proper way to get them to fit.
..
Dave, I did not reply because I don't know enough to understand the implications of running on 6 Volt batteries all boat systems that run at 12V.

You have 720 Ah at 6 Volts, that corresponds to 360Ah at 12V? Where it is made the conversion (6 to 12V)? There re losses on that conversion?

The main advantage is space?

I have a nice battery box right over the keel at the boat center:



The boat weights are carefully balanced and I don't want to change their place.

Eventually they can be higher (bigger) and have more capacity but I don't think I have an alternator with power for more than 360Ah on the home bank. I guess that what I really want to know is if the AGM with that alternator (120Amp) will charge in about half time (considering charging time of wet batteries 50% to 85%) and how many times in a month I will have to charge them to 100% for not shorten much their life span.

Regards

Paulo
 
#13 ·
Got two 105AH Lifelines for my Pearson 34 Spring 2006 and been quite happy with them. 80A alternator & next to never run engine to only charge batteries. Trickle charge w/20W solar panel. But I am also a power miser. Biggest draw is GPS & autopilot, radar when foggy (oh, never in Maine), although fog often coincides w.motoring.
Leave in place over winter, charge fall, charge spring.
 
#14 ·
i have a lifeline gpl 8dl battery and a morningstar controler pro 30 but lack enough solar panels,the controler won't allow the battery charge to get too low and when my rich uncle gets out of the poor house i'll add more panels,i have a seperate 2 battery bank for the engine and normal boat use and will be using the solar system for other things
 
#16 ·
360 ah means only 180 usable and if recharging on the hook without engine hard to get past the 85% part as you will also continue to use.

I would look at getting at least 4- 6 volt lifelines. Thats 440 or 480 depending on the ones you buy. The footprint space of the 4 6 volt will take up the room of less than 3 group 31. 3 group 31 is about 330 ah. Also you do not need battery boxes for the AGM just have to secure them although i did have the space for battery boxes. If you can get 6 in the space. I made dummies out of cardboard of the batteries and fit them into the compartment uinder my rear quarter berth to see the proper way to get them to fit.

Lastly I would make an electrical diet to see what you usage is in an average day. That should help you figure out how many ah you will need for what you want to do. Our average ah/ day is about 80-90, 40 of which on a hot summer ( 90+) day is refrigeration. We have shower pumps, fans, labtop,as well as a C-80 chartplotter and ST-60 instruments and had gone to all LED lights...most Alpenglow.

Good luck on your choices. These batteries will last more than 4 yaers if you take care of them properly during charging and make sure you desulfate them correctly.

Dave
 
#17 ·
I,m having to replace my 10 year old starter battery, won,t hold a charge, so understand I would be wise to replace the leisure at the same time.
Have a small AGM that runs my electric outboard. Holds the charge well and charges up quickly but going up in size to a pair of 100+ Ah is expensive.
I,m thinking of a like for like replacement as I think 10 years of reliable use is hard to beat.
 
#18 ·
That is super useful feedback from Maine Sail. I will go back to it and read slowly, comments & links. My study of the situation is not as technical.

Here's the backround: J/35, weekend cruiser, once a month if lucky, boat in dock, two kids & wife, Puerto Rico. It rains very often during evenings in the Caribbean (short & heavy), so I got sick of getting up to close hatches and then back up to open. Then came genset, 2.5K Mase, to run A/C. It "killed" the sailboat "feel" for sleeping, no matter the soundproofing & vibration damping (which was more important but I was limited in height). Genset out, and starter studying batteries further.

Decision: high accceptance rate, "virtually no gas emissions" (Deka-WM), putting high loads on them, and deep cycles (70% discharge). I upgraded alternator to a Balmar 70A, with programmable regulator.

Ok, about the A/C, I use it at night only, so it maintains a nice ambient temperature, not a refrigerator, like some of my boating friends. It's a Cruisair 10,000BTU/h, with a soft starter, which reduces load peaks. 3000W Gopower Inverter, and that's the system. I've run my A/C for 12h, very much over my calculations, but that depends a lot on the temperature difference you set (ext/int). Same story with your refrigeration, Paulo, tem and use (open/close). If you have two ref systems, have one to store unopened stuff and open it the least.;)

Custom made a SS crate for the new bank, on top of keel. My boat is a bit weight/balance sensitive, so that's a big plus. Need more experience on this, but I'm very excited. No dollar savings, just being a systems geek and sinking money, but this hobby/lifestyle doesn't make economical sense since the day you consider to buy a boat. I'll admit wasting some more than usual, but I also learn in the process.

Warnings, this is just as costly as a generator, but I think it's the future, especially in under 40' boats. Why hasn't the inverter-type technology of A/C gone marine yet? That will change the world of onboard power requirements. Next thread topic, Paulo?:)

Here's a picture of the bank. Made a custom cabinet/table over it, not pictured. Seventh batery is aft port, opposite to starting battery. Have a Link 2000 monitor but have yet to learn how to program it correctly.
 

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#20 · (Edited)
Decision: high accceptance rate, "virtually no gas emissions" (Deka-WM), putting high loads on them, and deep cycles (70% discharge). I upgraded alternator to a Balmar 70A, with programmable regulator.
With that alternator you are not even coming close to taking advantage of the acceptance benefit. The same bank it Wet Cell would take well over twice what you can effectively deliver. Deka recommends cycling the batteries to 50%...

Ok, about the A/C, I use it at night only, so it maintains a nice ambient temperature, not a refrigerator, like some of my boating friends. It's a Cruisair 10,000BTU/h, with a soft starter, which reduces load peaks. 3000W Gopower Inverter, and that's the system. I've run my A/C for 12h, very much over my calculations, but that depends a lot on the temperature difference you set (ext/int). Same story with your refrigeration, Paulo, tem and use (open/close). If you have two ref systems, have one to store unopened stuff and open it the least.;)

Custom made a SS crate for the new bank, on top of keel. My boat is a bit weight/balance sensitive, so that's a big plus. Need more experience on this, but I'm very excited. No dollar savings, just being a systems geek and sinking money, but this hobby/lifestyle doesn't make economical sense since the day you consider to buy a boat. I'll admit wasting some more than usual, but I also learn in the process.

Warnings, this is just as costly as a generator, but I think it's the future, especially in under 40' boats. Why hasn't the inverter-type technology of A/C gone marine yet? That will change the world of onboard power requirements. Next thread topic, Paulo?:)

Here's a picture of the bank. Made a custom cabinet/table over it, not pictured. Seventh batery is aft port, opposite to starting battery. Have a Link 2000 monitor but have yet to learn how to program it correctly.
Your bank can become "imbalanced" if you keep it wired like that..



Yours looks wired like this:
 
#22 ·
I have 3 Group 31 West Marine branded AGM's that I bought in '06. 70 amp alternator w/ext regulator, wind generator, and a Honda 2000 that I use to run the battery charger on the hook. I'll be replacing my AGMs this spring. Cost depends on where and how you buy them.
 
#27 · (Edited)
Paulo,

2 -6 volt batteries placed in series= 1 12 volt battery...then placed in parrallel. Each seried pair of batteries is 240 ah. 3 groups of seried batteries =720 ah of 12 volt power.

If you have 360 ah of batteries- charging at 120 amp alternator ( thats what I have and Maine sail recommends electromax alternators vs Balmar) , and the 360 ah batteries dont discharge below 1/2 or 180 ah and you want to get to 85% by engine charge you have approx 150 you need to get in which is about 1.25 hours of engine time to get 180 ah.


If you had 720 ah of batteries you could go twice as long without charging as you need to charge 360 ah in. Alsdoo a passive charger like you are planning on will help this too.


This way you do not have to be a frugal with your energy like turning of refrigeration etc. We can generally go 5-6 days without using the engine.

Dave
 
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#35 ·
Thanks, Maine Sail. Before going into this, I did an Excel worksheet. I do remember Peukert factor and had taken it into account. The bank is 735Ah (7th battery not in picture). I was afraid of a larger alternator due to my engine size (Yanmar 3GM 20hp), but I had not realized the heat issue having it work overtime. (I assumed these expensive Balmars were designed for that duty-yes, it's a 6-series). I did calculate 6 hrs recharge time, but would rather run engine during the day than a genset at night. Again, the longest stay in my boat is 4 days, and usually its just two nights (long weekend). The A/C is drawing 77A on cooling cycle and 7A on fan cycle (measured on the battery cable). Should I upsize alternator? I'd have to change pulley in that case. Running at idle, mine is putting 55A into the batteries. I have also done 4 hours running engine and A/C and it seems to balance out consumption (batteries remain at same exact voltage). Maybe consider some solar to make up for the deficiency? wind too? It seems renewables are insignificant when talking about these loads, but then again, it may add up? I will install alt. temp sensor at least. Thanks again, Hans.
 
#40 · (Edited)
As you have seen I am learning but I have made some research regarding my problem and particularly regarding size of alternator and the use of a generator so a question to you:

It seems that you have used an AC generator to run your Air conditioner and that means having the generator working most of the time and making a lot of noise. But there is another alternative, why don't you sell that generator and get one of these?:

D.C. Traveller | HFL

They are small light (72kg) and produce directly DC current via an integrated powerful alternator (140 Amp). This works not powering directly the Air Conditioner, but charging the batteries. If you run this baby and the engine at the same time you will get 210Amp on alternators and even considering losses with temperature they will be good for about 170 Amp charging power that is 3 times more than you have now. That would reduce the charging time of your batteries to about 2 hours, and that seems more reasonable to me.

There is also this one, but it seems heavier and bigger even if a lot more powerful. With this one you would charge your batteries in a bit more than an hour (using also your engine). this one looks more expensive and would be more adequate to your battery bank but not to the size of your boat.

Marine Micro-Cogen for recreational and commercial vessels

The other one is not expensive and I am sure is no bigger than the generator you have, probably smaller.

Hei Mainsail, please see if I am saying a lot of rubbish please:D

Regards

Paulo
 
#36 ·
Boy, it is good so see knowledgeable folks on this forum. Reminding people of the Peukert effect, most aren't aware of the fact that the larger the wattage draw from a battery, the less the capacity over advertised a/hr rating. My next battery bank will be LiFePO4 and 48 volts for the inverter. I have used the Odyssey AGM batteries and couldn't be happier (except the cost). Lowest self discharge, highest surge amps per weight, no corrosion, accepts 3.0C instead of 0.1C of flooded, and much longer life than flooded.
 
#37 ·
I have used the Odyssey AGM batteries and couldn't be happier (except the cost). Lowest self discharge, highest surge amps per weight, no corrosion, accepts 3.0C instead of 0.1C of flooded, and much longer life than flooded.
Just curious how long you've had your TPPL's? I have three customers with them but the oldest bank is at year three and will be getting an Electromaax serpentine kit and 160A alt this spring. According to the analyzers they are still doing okay. Not ready to jump in full swing as I got burned hard by AGM doing that. Still waiting on the longevity reports for TPPL in the marine space...

Would love to hear some TPPL success stories in the 6+ year range...
 
#39 ·
Maine as always excellent information. I am going down today to put a small wood block between each of the batteries to allow heat removal space.

Glad you satyed here..:):):):):)
 
#41 ·
Good info, Paulo, especially if my boat grows one day. One of the reasons I also eliminated the genset is that I felt the weight aft, although it is only 145#! The boat now feels very well balanced, and that is a priority too. After yesterday's advice, I'm considering adding 1. wind, 2. solar, and then a larger alternator (maybe 6-series 140A). Again, I'm mostly a weekender and for that, the actual setup is more than adequate, but I certainly don't want to cook my alternator. Excellent info on this thread though! I'll keep watching.
 
#47 · (Edited)
Should be enough. He is only needing 15.2 volts for charging, and at the alternators full output of 165 amps, should only use about 3.5 hp. Now if he was charging my proposed 48 volt bank at the same 165 amp, that would only leave 6 hp for main propulsion, a bit on the low side for a 35' boat.

Besides, he can via the field, switch the alternator off should he need more power for propulsion.
 
#55 ·
Should be enough. He is only needing 15.2 volts for charging, and at the alternators full output of 165 amps, should only use about 3.5 hp. Now if he was charging my proposed 48 volt bank at the same 165 amp, that would only leave 6 hp for main propulsion, a bit on the low side for a 35' boat.

Besides, he can via the field, switch the alternator off should he need more power for propulsion.
That seems interesting but I have no idea of what you are talking about. Please, do you mind to explain how I can prevent the alternator from taking away power from the engine without physically disconnect the transmission rubber?

Regards

Paulo
 
#48 ·
Check out electromaxx alternators vrs Balmar. Was recomended to me by Maine Sail. Have been very haoppy with it and a change to sepentine belt on GF30 Yanmar Plus temp sensor

Dave
 
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