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  #11  
Old 03-19-2013
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Re: AGM batteries

We did the AGM thing for a while, and then when we left the dock, we couldn't get 3 months out of them. The manufacturer and engineer who installed our electrical system along with Balmar all went over my system and concluded that it must have been a bad batch of batteries. The manufacturer sent us replacement batteries on freight for free. Balmar even replaced our voltage regulator for the alternator. Then after being at anchor for about 6 months, we had problems with the replacement batteries.

We have since went back to wet batteries with no issues.
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  #12  
Old 03-20-2013
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Thanks for all the replies. I do like the lack of maintenance with the AGM batteries but I'm uncertain of how much longer they will last. I would rather go to the flooded style in the future when they die. Is there any way I can determine the potential life left in these batteries?
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Old 03-20-2013
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Re: AGM batteries

You can load test them. Fully cycle them, charge them 100% and let them stand, then put a load test on them. You can buy load testers under $50 for something that small on Amazon (3x higher at the local auto store) or maybe borrow one for free from Autozone or Pep Boys tool rental program. Or take the batteries into a shop and ask them to do a load test, usually free.

You can also load test them by fully charging them, then connecting a load like a headlight and timing it until the voltage drops. Or fully charging the batteries, letting them stand overnight, and then using a good accurate digital multimeter and assuming 12.6 was a new battery, derate them 10% for each 1/10th of a volt they are below that. That's not perfect, because meters aren't dead accurate and 12.6 isn't a universal truth, but it will give you a "1/8-1/4-1/2-3/4" type profile versus the label rating.
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Old 03-20-2013
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Re: AGM batteries

Quote:
Originally Posted by Letrappes View Post
Thanks for all the replies. I do like the lack of maintenance with the AGM batteries but I'm uncertain of how much longer they will last. I would rather go to the flooded style in the future when they die. Is there any way I can determine the potential life left in these batteries?

Scott,

Easiest way to get a reliable estimate of remaining capacity is to find someone with a sophisticated inductance/capacitance tester, like the Midtronics series. These are too costly to buy for your needs (about $600), but they'll tell you the remaining capacity pretty quickly.

Failing that, there's only one reliable way to test remaining capacity, and that's by doing a controlled C/20 load test. This means you fully charge the batteries, then attach a resistive load calculated to be approximately 1/20th the battery capacity, and let it go for upwards of 20 hours or until the voltage drops to 10.5VDC.

A group 27 AGM has between 90-100AH capacity. Say 100AH to make the calculation easy. So, if you hooked up one of these to a load you'd want a 100/20 = 5 amp load. Five amps @ 12 volts = 60 watts, so a 60 watt load would be appropriate to do a load test on one of your group 27 batteries.

As noted above, a halogen car headlamp might do the trick. These tend to be about 55 watts or 4.6 amps....a little less than the target 5 amp load. And, guess what? If your AGM battery were only about 92AH instead of 100AH -- as many are -- then the 4.6 amp load would be right on target :-)

Alternatively, you can probably find four 15-watt 12V bulbs at West Marine. Hook all 4 up in parallel and attach to the battery under test. Then, take periodic voltage readings over the next hours until you get to 10.5VDC.

If you only get 10 hours, that means the battery only has 1/2 capacity left.

If you only get 5 hours, that means the battery only has 1/4 capacity left.

When you're done testing each battery, be sure to fully charge it....don't let it sit discharged.

Good luck. Let us know what you find.

Bill

Last edited by btrayfors; 03-20-2013 at 06:22 PM.
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Old 03-20-2013
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Re: AGM batteries

Maine...is this true?

•The higher charge efficiency of AGMs allows you to recharge with less energy: Flooded cells convert 15-20% of the electrical energy into heat instead of potential power. Gel-cells lose 10-16% but AGMs as little as 4%. The higher charge efficiency of AGMs can contribute to significant savings when it comes to the use of expensive renewable energy sources (wind generators, solar panels, etc.) as your charging system can be 15% smaller (or just charge faster).

I am not arguing with you about the use of AGM. There is a lot of misinformation printed then. I am able to get mine back up to 100% quickly, but eventually I will need to replace them, My 6 volt Lifelines are now 5 years old and going strong. Part of me using them is their inaccessability and that I have two laying on their sides.

This is not correct information then?

Battery Types: Flooded versus AGM and Gel
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Old 03-20-2013
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Re: AGM batteries

Quote:
Originally Posted by chef2sail View Post
Maine...is this true?

•The higher charge efficiency of AGMs allows you to recharge with less energy: Flooded cells convert 15-20% of the electrical energy into heat instead of potential power. Gel-cells lose 10-16% but AGMs as little as 4%. The higher charge efficiency of AGMs can contribute to significant savings when it comes to the use of expensive renewable energy sources (wind generators, solar panels, etc.) as your charging system can be 15% smaller (or just charge faster).

I am not arguing with you about the use of AGM. There is a lot of misinformation printed then. I am able to get mine back up to 100% quickly, but eventually I will need to replace them, My 6 volt Lifelines are now 5 years old and going strong. Part of me using them is their inaccessability and that I have two laying on their sides.

This is not correct information then?

Battery Types: Flooded versus AGM and Gel
Dave,


You are using your AGM's for one of their actual "benefits", this is GOOD.. I RARELY see more than hand full of boaters taking advantage of any of the real pluses of AGM's..

Much of that information from that site is correct and much of it is very "dreamy"... For example that article is still in the "fantasy" stages of AGM technology where they sold us on 80% DOD's and suggested you could get away with a smaller bank. That marketing "tune" has changed big time..

This is straight from the Lifeline tech manual.

"For example, if 100 Ah is required on average, select at least a 200Ah battery. This approach will limit the average depth of discharge to 50% and will dramatically extend the life of the battery.

To get the best cycle life, the average depth of discharge should be as low as possible. Concorde (Lifeline) recommends the average depth of discharge be no greater than 50% of the battery’s 20 hour rating."


They are not recommending 3:1 bank sizing as that article insinuates, they are suggesting 2:1 bank sizing just as flooded batteries are sized for. I referenced this in the above post and it is 100% backed up by the AGM makers themselves, including Lifeline, which that article seems to tout. The only exception to this that I am aware of is Odyssey who still market at 80% DOD and 400 cycles.

This one element alone throws a HUGE monkey wrench into the entire bank sizing calculations for that site. It would also be better for the math if he had rated the T105's at what Trojan does, which is about 1200 cycles to 50% DOD.. It is right on the T105 Tech Data sheet.

One other thing I find rather odd or perhaps misleading is his use of the West Marine batteries in the cost comparisons. It is NOT a secret that WM slaps a Sea Volt sticker on Deka/East Penn batteries. They are the MOST EXPENSIVE reseller of these batteries or put another way that Sea Volt sticker is VERY expensive.....

Heck the Group 31 12V Deep Cycle was selling for $247.99 in last yeas catalog. That SAME battery can be purchased at Sam's Club for $84.97..

Sams Club = Group 29/31 (Deka DC31) 105Ah Battery $84.97

West Marine = Group 31 (Deka DC31) 105Ah Battery $247.99


Difference = $165.02 per battery !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I honestly wonder how the math would have worked out had he compared the least expensive re-seller of the SAME battery rather than the MOST expensive......????? Inquiring mids are curious...

The SAME batteries can be purchased at NAPA, O'reilly Auto, Sam's Club and many other locations for considerably less than HALF the cost of West Marine. Of course on the flip side, if you use West Marine as your basis for cost analysis, it helps make the Lifeline Battery look better...

AGM's charge faster. No secret there and I DO take advantage of this on many installations. Where customers CAN take advantages of the faster charge, and they fully understand that life cycles may not be as good as they suspect, I have no issues installing AGM's and in many cases actually recommend them..

Another big problem is that most boats I go on can't even meet the minimum suggested charge capacity for AGM's, 40% of "C" for Odyssey and 20% of "C" for Lifeline so it makes very little sense to spend huge money on a system we already know will be on the short side of longevity by having a limited charging system.

The other "never talked about" issue is that when AGM's are new they take GOBS of current. New however does not last very long if the batteries do not get back to 100% after every discharge cycle. For mooring sailors this a tough issue. Lifeline specifically notes this in their warranty.

"The limited warranty does not cover discharged batteries, batteries that have been opened, frozen, sulfated batteries due to undercharging, diminishing capacity due to battery age, split open battery cases, transportation, rental, testing, housing, freight or installation costs."

Back in the real world, not warranties worth about as much as the paper they are printed on, I have a 4 year old bank of Lifeline 6V batteries to replace in the next month. They are currently taking just 65-80A in bulk/in-rush and hitting absorption voltage within a few minutes. The alternator, when loaded, goes right up to its 150A cold rating. Customer initially blamed the alternator and regulator and spent HUGE money having the alternator re-built and purchasing a new replacement regulator. Same issue... He calls in the boat yard, they diagnose it as poor wiring and replace it to the tune of $1600.00. OUCH!!! Same problem. Finally I get a call show up, test the batteries, measure internal resistance, fire up the motor and say: "you need new batteries".... "But they are only 4 years old, it can't be the batteries.".... I plug my heat gun into the inverter, fire up the motor and put my Fluke around the alternator output wire. What would you know 150A and the alt and reg are working just fine. Turn off the heat gun and right back to 65A of acceptance..... As it sits now this bank of four 6V batteries takes about 12+ hours to get to a full charge due to the sulfation. So yes when new, how all the marketing is done, they can and do charge faster. However unlike flooded or GEL cells they really don't like to sit at anything less than 100% SOC or they sulfate and performance, including charging performance, suffers and seems to suffer faster than with GEL or flooded LA batts..

From Lifeline:
"For repetitive deep cycling, chargers should have an output current of at least 0.2C (20 Amps for a 100 Ah battery). If the output current is less than this value, the cycle life of the battery may be negatively affected."



Hell beyond the initial 3:1 bank sizing or 80% DOD we were sold on, we were also led to believe early on that AGM batteries did not even sulfate.. Talk about marketing. I can clearly remember the marketing guys telling me "you never need to equalize an AGM battery because they don't suffer from sulfation." SWEET!! So I went out and installed a few banks, based on the "glossy marketing"....... Hmmm guess what? They sulfated..... Doh'........

With AGM's I hear so many people claim they bought them for "high acceptance rates" then they feed a 450Ah bank with an 80A alt that when hot puts out 60-65A or about 14% of capacity or 6% below the minimum suggested by Lifeline.

Heck that same bank in flooded batteries will take the full hot capacity of a 125A alternator or slightly more..

Back in the real world I work in, a customer just last month called me to ask if he really needed to be there for the 8 hours he was going to be equalizing his Lifelines for. Ummmm YES, how else are you going to monitor the battery temperature during this over voltage event....!!!! Makes adding distilled water to some flooded cells seem like cake walk.... 8 hours of 15.5V for a "conditioning charge", but they are sold as "no maintenance". At year two he is already noticing "diminished capacity" hence the conditioning charge. That said AGM batteries are this customers best option due to fitment, containment and because he actually has a 180A alternator. Cost is not an issue for him.

Again, AGM's HAVE NUMEROUS benefits its just that cost and cycle life are not either of them....
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Last edited by Maine Sail; 03-20-2013 at 11:43 PM.
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  #17  
Old 03-21-2013
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Re: AGM batteries

Maine,

Thanks for the explaination

The chart in the link shows the Lifelines at 1000 cycles at 50% discharge.

I have done what was described with a 660 ah bank which rarely goes below the 75% discharge. I do have the availability to get close to the 100% no with the new alternator and shore power master volt charger.

I kaois have been desulfating when neccessary at 15.5, but not for the whole 8 hours...maybe 6 as I watch the temp readings

I porabbly have paid more attention to batteries since I bought these than I do anything else on the boat it seems. My wife says I am obsessed with it.

When these finally wear out I proably will go to the gells if I still have Haleakula, as they are really inaccesable.
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  #18  
Old 03-21-2013
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AGM batteries "Depends"

In my case AGM's seem to have done well. When I say in my case, I am talking about going on 7 years with 2 Optima AGM's. I just pulled them and had them checked at Interstate on one of those high dollar testers that Maine Sail recommends. In fact they showed quite a bit above there "rated" capacity. Unfortunately, I don't have a baseline to compare them to since I didn't have them checked when I first bought them.

Since the boat sits on a trailer most of the time and they have been discharged rarely, usually never below 11.0 - 11.5 volts (?) They have also been connected to a fan running 24 hours/365 days a year for the past 5 (?) years. They have been connected to a 20w solar panel with a Morningstar Duo controller (4 stages).

They have never been "equalized" and only occasionally I throw them on a pulse charger over night. I'm not saying that I recommend the way they have been maintained, only listing the facts.

I realize if you are a cruiser and actually get to use your boat regularly and your batteries go through the normal discharge cycles, your mileage will vary.

Although they have held up well, I got them at a ridiculous price from a friend years ago. I would find it hard to pay what they go for now. They are nice because the batteries are hard to get to if I had wet cells it would be a pain.

They will now probably go belly up.
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Old 03-22-2013
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Re: AGM batteries

Chef & Maine, you guys really make this forum the best, thank you! Yet another interesting topic.

Once the admiral and I finally cast off our lines I was planning to replace all the wet cells with AGM's. I have been following AGM for a number of years and while hearing all sorts of positive remarks, occasionally I would hear about the consistent need of equalizing the batteries. It seemed anytime Lifeline received an issue from a customer their response was, equalize. I did make sure my regulators for my 100amp charger and 210 Balmar supported equalization. But more recently I have been put off by this idea. What am I to do when laying off of Dominica with my AGM's in need of an equalization treatment? I have felt recently that I need to re-examine this approach. This thread pushed me over the edge.

While looking at the Rolls website the other day they noted their AGM's do not need equalization ever. WTF? They note the use of Pure Lead which gets into the new Marketization term of "TPPL" (thin plate pure lead). Is this the resolution to this AGM issue? Or yet another marketing ploy to lead me astray. This is very frustrating trying to get past all the BS.

With a use budget of 200-250 amps per day, (2) D400's and a 10amp solar panel and the above mentioned charger/alternator which way should I go? I was thinking a 600a/h house system. We are not dock marina people, laying on anchor is what we prefer.

Last edited by kellysails; 03-22-2013 at 02:17 PM.
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Old 03-22-2013
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Re: AGM batteries

md, even a nuclear pile loses some capacity over seven years. So if someone tested your Optimas and found them above rated capacity after seven years, I'd say they are in great shape--but the test may have been done wrong, one way or another. Even if you never used them and simply kept them on a float charge...after seven years...most unusual.
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