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Old 26-09-2011, 08:35   #31
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Re: Agm vs Sealed lead acid

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Originally Posted by Maine Sail View Post
Very true but in the real world 9.5 out of 10 boats I work on do not have the capability to take advantage of the high acceptance of AGM's thus this benefit is very often being wasted..

Heck, half the boats I work on can't even charge at the 25% +/- that deep cycle wets can accept once the banks get big..

Also:

This is what Lifeline suggests for expected life based on care. How many of you guys fall into scenario #4?

#1 Fully charge after each discharge. Estimated life: 6-9 Years

#2
Fully Recharge at least once a week and equalize once a month. Estimated life: 4-6 Years..

#3 Only recharge to 85% and equalize once a month. Estimated life: 2-4 years.


#4 Only charge to 85% and never equalize. Estimated life: 1 year.

Disclaimer: This was originally posted on the Morgan's Cloud web site and was an eye opener. I then called Lifeline and spoke with Justin G. to confirm this is still what they expect. It is..
G'Day MS,

That's really interesting info, and it reflects my observations around the cruising fleet. I wonder what that sort of analysis would say about T-105s or other decent quality flooded batteries?

It would be great to be able to achieve category one status, but for those without gen sets it would be difficult. A really big solar bank (relative to usage) might do it, but dark days could mess up the schedule.

Anyhow, thanks for posting that... should open a few eyes!

Cheers,

Jim
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Old 26-09-2011, 08:49   #32
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Re: Agm vs Sealed lead acid

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G'Day MS,

That's really interesting info, and it reflects my observations around the cruising fleet. I wonder what that sort of analysis would say about T-105s or other decent quality flooded batteries?
.....
Jim
From further on in the Morgan's Cloud site
By the way, Justin claims that there is really no difference in the care required for his AGM batteries and traditional liquid filled batteries. In other words, he is saying that the latter will fail just as quickly as the former if not regularly fully charged and equalised.
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Old 26-09-2011, 09:00   #33
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Re: Agm vs Sealed lead acid

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From further on in the Morgan's Cloud site
By the way, Justin claims that there is really no difference in the care required for his AGM batteries and traditional liquid filled batteries. In other words, he is saying that the latter will fail just as quickly as the former if not regularly fully charged and equalised.
Yeah Justin told me that too but in the real world I do not find that to be true at all and he never argued that point only to say "in theory". Wets in marine applications seem to be a lot more tolerant of abuse than AGM.

I have one customer with a Sabre who got 7 years out of cheap 6V wets (Exide) with only a dumb regulated stock alternator. The batteries were never equalized in the seven years he used them. He switched to AGM (Lifeline) and upgraded his alt and regulator at the same time (Balmar w/temp sensing etc.). His AGM's with the identical use, weekends and a two week cruise, lasted until the end of June of his fourth season. In Maine this is really about 3.3 seasons use. He's back to wets. This is but one of many similar stories I see with mooring sailed boats and AGM. On the other hand Gel Cells seem to last for a very long time if properly charged.
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Old 26-09-2011, 09:20   #34
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Re: Agm vs Sealed lead acid

Quote:
Originally Posted by Maine Sail View Post
Very true but in the real world 9.5 out of 10 boats I work on do not have the capability to take advantage of the high acceptance of AGM's thus this benefit is very often being wasted..

Heck, half the boats I work on can't even charge at the 25% +/- that deep cycle wets can accept once the banks get big..

Also:

This is what Lifeline suggests for expected life based on care. How many of you guys fall into scenario #4?

#1 Fully charge after each discharge. Estimated life: 6-9 Years

#2 Fully Recharge at least once a week and equalize once a month. Estimated life: 4-6 Years..

#3 Only recharge to 85% and equalize once a month. Estimated life: 2-4 years.

#4 Only charge to 85% and never equalize. Estimated life: 1 year.

Disclaimer: This was originally posted on the Morgan's Cloud web site and was an eye opener. I then called Lifeline and spoke with Justin G. to confirm this is still what they expect. It is..

MS:

Interesting info. I probably fall into the first catagory. With electric propulsion it's all about the battery bank. I usually don't let my electric propulsion bank fall drop below 80% before I start charging. I can move my boat about 3 knots in calm conditions using just 900 watts from the Honda generator. So there is additional power I could tap into for charging if I needed too. But, since I often electro sail (to reduce prop drag) most of the power can go to charging while underway which means less generator run time (if any) while at anchor. Solar and wind keep things topped up very nicely after that. This works well for me.
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Old 26-09-2011, 09:34   #35
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Re: AGM vs Sealed Lead Acid Battery

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Old 26-09-2011, 10:12   #36
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Re: AGM vs Sealed Lead Acid Battery

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I have 5 x 105Ah AGMs, a 110A alternator and 2 x 130W solar panels...I have had this setip for 5 years now and the batteries still have >90% of their new capacity.
I am just curious what type of refrigeration you have? I have two 80W solars and the same battery capacity, but there is no way the solars will power the refrigeration alone. I think it's more like 60% or less.
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Old 26-09-2011, 13:23   #37
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Re: AGM vs Sealed Lead Acid Battery

My concern with wet cells goes to the steep self discharge and having the battery freeze during winter layup. A wet cell 8D will weigh in at around 140 pounds so moving several of them off and on the boat is not my idea of fun so I leave my AGM's (165 lbs) on board all winter. Do wet cells freeze if put to bed fully charged?
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Old 26-09-2011, 13:42   #38
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Re: AGM vs Sealed Lead Acid Battery

"Maintenance Free" liquid lead acid batteries like those sold in places like Walmart are not really "sealed" batteries although they appear to be. You can open them with a flat bladed screwdriver and check the water level and refill as necessary. And they must be used upright.
- - The "exotics" - AGM and Gel have applications were you will be away from an easy source of replacement batteries but they do need very good charging regulators and discharge metering to get the maximum lifespan.
- - But, IMHO, the biggest difference is in the price of liquid lead acid batteries versus the price of the "exotics." AGM prices typically are a multiple of liquid lead acid. So you use and replace the liquid lead acid a few times before you equal the cost of the exotics.
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Old 26-09-2011, 13:50   #39
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Re: AGM vs Sealed Lead Acid Battery

Fully charged batteries never freeze, independent of type. A wet cell has a higher self-discharge, so you need more current to keep it fully charged. But the current is so lo so even a small solar-panel under a tarp gives enough current to keep the batteries fully charged. Of course, you can’t have ANY other load on the batteries. (20 W panel, 400 Ah battery)

A gel and AGM have so little self-discharge, so they will probably survive a winter without a solar-panel. But is it worth the risk?
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Old 26-09-2011, 15:40   #40
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Re: AGM vs Sealed Lead Acid Battery

For me, the biggest difference is efficiency. Since 100% of my power is solar (windgen broke) wasting power is not ideal. Someone mentioned flooded self discharge rate is twice that of AGM. That is about right, but also keep in mind flooded is only 80% efficient round trip vs 90% for AGM. Then on top of that.. when you are topping off the flooded or equalizing the efficiency drops to 50% or lower. For this reason I would find AGM more desireable in renewable systems.

That being said I have 832ah in flooded batteries because they are cheaper. I find periodically I get 3-4 days in a row of clear sky and ample sun to equalize the bank. During this time I have excess power anyway, so it seems to work out ok.
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Old 26-09-2011, 16:11   #41
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Re: AGM vs Sealed Lead Acid Battery

We replaced our Lifeline AGMs recently with new Lifeline AGMs.

The reasons:

1) They reside in our living area. Flooded cells vent hydrogen gas (a LOT of it - look it up) and they aren't in our ventilated engine space.

2) Our charger already was set up for AGMs

3) No mess.

If you have #1, I can't recommend AGMs highly enough. No matter what anyone on here or anywhere else tells you, flooded cells HAVE to be very well ventilated.
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Old 26-09-2011, 16:59   #42
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Re: AGM vs Sealed Lead Acid Battery

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My concern with wet cells goes to the steep self discharge and having the battery freeze during winter layup. A wet cell 8D will weigh in at around 140 pounds so moving several of them off and on the boat is not my idea of fun so I leave my AGM's (165 lbs) on board all winter. Do wet cells freeze if put to bed fully charged?

Our wet cells are and have always been stored either on-board or in the un-heated barn, a non-issue. I actually prefer cold storage to basement or warmer.. I sometimes top them up over the winter but usually not. This spring they were still at 12.68V after last being charged in early November.

Colder temps drastically slow self discharge and sulfation. I have never had a battery freeze because we've never seen temps of -70F... We did have temps of -29F back in the 90's and still none of our batteries froze.

As long as wets remain charged they won't freeze.. Lived in Fairbanks, AK so understand cold well, and it gets MUCH colder there than here in Maine.....
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Old 27-09-2011, 14:41   #43
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Re: AGM vs Sealed Lead Acid Battery

I'm in the process of switching out diesels for electric drive. Also going to a full electric galley, electric hot water, and electric digny. I do not want any gas, diesel, propane, or kerosene on board period. I am going the AGM route for a number of reasons. This type of battery has a dual personality, that of deep cycle and cranking battery. Self discharge is even less than has been stated in previous posts. No corrosion on battery or the surrounding envioroment the batteries placed in. With proper care, the AGM batteries I'm going with will cycle 1200 times to 80% discharge. The digny will use Odyssesy AGMs, the best I have ever had. One Hawker PC680, just a 15 lb battery has started my 10.3 to 1 hot rod for 17 years and now is starting my lawn tractor. (4) of these same batteries power a home built hot rod scooter that can out pace my Corvette to 40 mph and have propelled that scooter for 1800 miles.







I will be using a 48 battery string of 2 volt, 700 a/hr, AGM batteries with a controller for the electric motor drives that has regen built in. The props can pitch for astern for setting the hook with some good tug, but if left in that pitch setting while under sail, can use regen for charging the battery bank. Another nice feature about AGMs, while a regular flooded doesn't want to be charged any faster than 0.1C, AGMs will take 20 times that charge rate. Under sail, it is just a matter of how much regen you want to run and how much sailing speed you are willing to sacrifice. For extended periods on the hook, and poor solar days, you can just pull up anchor and go for a day sail at max regen and your good for another two weeks on the hook.
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Old 27-09-2011, 15:10   #44
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Re: AGM vs Sealed Lead Acid Battery

How are you going to charge the batteries?
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Old 27-09-2011, 15:14   #45
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Re: AGM vs Sealed Lead Acid Battery

Clearly people's experience varies a lot. I have 2 lifeline 4D agms on my boat and they'll be 10 years old in February. So far they're holding their own but it's clear capacity is down a bit from when they were new. I'm sure to be replacing them soon. I'll admit that they've spent a lot of time plugged into the dock. On the otherhand I have a friend who just replaced his 8D lifeline in his Mainecat after 8 years and it had never been plugged into a charger. He had 4 55amp solar panels and is convinced that the battery would have still been going strong if he had not suffered a simultanious failure of two of his solar panels and a runaway tilt/trim motor that drained his battery to nothing overnight when he was not on board. The battery was never right after that and had top be replaced. He has refrigeration on board and cruised the bahamas for at least 4 months every winter. He never equalized the battery and his only other charging sources were the 8 hp outboard alternators. He would occasionally go three or four cloudy days without a good charge. I would guess he got somewhere between 1500 and 2000 cycles out of that battery.

I am debating what to do about my batteries now. I'm even considering investing in LiFePO4. My battery box is in the living space and I have no desire to deal either with acid fumes or hydrogen gas venting. I'll probably go with the Lifelines again as my system is already set up for them and I'm not sure I want to become battery test bed which I fear I would become with LiFePO4.
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