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20-01-2017, 11:12
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#46
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Registered User
Join Date: Mar 2012
Location: On board in Leros, Greece
Boat: Hunter Legend 420 Passage
Posts: 863
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Re: What batteries are you using and where are you buying them?
Quote:
Originally Posted by jcapo
...Lifeline AGM if you can afford them and you can fully charge them several times a week...
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Quote:
Originally Posted by OrangeCrush
.... but only if you can plug into shore power VERY regularly, or have plenty of solar, so that you bring the AGMs up to 100% between every use....
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Quote:
Originally Posted by skipmac
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I also wonder about the frequent use of AGMs in boats....unless you're at a dock very frequently or run a genset hours every few days you aren't really treating AGMs the way they like for long life...
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Fully charging AGMs after every discharge is a myth that has been mis-interpreted from an article on MorgansCloud site from Lifeline itself. Does anybody have any other evidence from a reliable source that AGMs need more regular charging the FLAs?
Justin Godber at Lifeline did define what expected battery life could be for their AGMs, depending on charge regime, assuming daily discharge to 50% and full time voyaging:
Fully charged after each discharge. Estimated life: 6-9 Years.
Fully recharged at least once a week and equalized once a month. Estimated life: 4-6 Years.
Only recharged to 85% and equalized once a month. Estimated life: 2-4 years.
Only charged to 85% and never equalized. Estimated life: 1 year.'
On the same website he went on to say that AGMs are like all Lead Acid batteries which ALL need to be fully charged after each discharge.
He also went on to say: "This is not feasible on a voyaging boat."
I "fully" re-charge my Lifeline batteries on shore power at least once every three weeks and they have lasted 12 years as a full time liveaboard.
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20-01-2017, 11:21
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#47
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S/V rubber ducky
Join Date: Jul 2007
Location: heading "south"
Boat: Hunter 410
Posts: 20,362
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Re: What batteries are you using and where are you buying them?
Quote:
Originally Posted by sailinglegend
Fully charging AGMs after every discharge is a myth that has been mis-interpreted from an article on MorgansCloud site from Lifeline itself. Does anybody have any other evidence from a reliable source that AGMs need more regular charging the FLAs?
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And if you read the poll below you will find that for cruisers batteries don't get fully charged anywhere near as much as threads here make it sound.
http://www.cruisersforum.com/forums/...en-177442.html
__________________
Don't ask a bunch of unknown forum people if it is OK to do something on YOUR boat. It is your boat, do what you want!
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20-01-2017, 11:55
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#48
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Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
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Re: What batteries are you using and where are you buying them?
Quote:
Originally Posted by sailinglegend
Fully charging AGMs after every discharge is a myth that has been mis-interpreted from an article on MorgansCloud site from Lifeline itself. Does anybody have any other evidence from a reliable source that AGMs need more regular charging the FLAs?
Justin Godber at Lifeline did define what expected battery life could be for Fully charged after each discharge. Estimated life: 6-9 Years.
Fully recharged at least once a week and equalized once a month. Estimated life: 4-6 Years.
Only recharged to 85% and equalized once a month. Estimated life: 2-4 years.
Only charged to 85% and never equalized. Estimated life: 1 year.'
On the same website he went on to say that AGMs are like all Lead Acid batteries which ALL need to be fully charged after each discharge.
He also went on to say: "This is not feasible on a voyaging boat."their AGMs, depending on charge regime, assuming daily discharge to 50% and full time voyaging:
I "fully" re-charge my Lifeline batteries on shore power at least once every three weeks and they have lasted 12 years as a full time liveaboard.
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I could have missed it but don't recall anyone saying you must fully recharge AGMs after every discharge. I recall often or frequently as the comments.
Have not gone to the original documentation to verify myself but I have seen a number of posts by very reputable members referencing information from the AGM battery manufacturers that recommended fully charging AGMs on a "regular" or "frequent" basis.
If I may ask, what do you see as the benefits to AGM batteries over FLAs? One poster mentioned the maintenance free aspect. Most of the posts from member recommending AGMs, when they mention their onboard charging capacities, don't seem to have enough capacity to take full advantage of the AGM's ability to take a higher rate of charge than FLAs.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
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21-01-2017, 09:47
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#49
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Registered User
Join Date: Mar 2012
Location: On board in Leros, Greece
Boat: Hunter Legend 420 Passage
Posts: 863
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Re: What batteries are you using and where are you buying them?
Quote:
Originally Posted by skipmac
I could have missed it but don't recall anyone saying you must fully recharge AGMs after every discharge. I recall often or frequently as the comments.
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This came from Lifeline in my post #46.
"Justin Godber at Lifeline did define what expected battery life could be for their AGMs, depending on charge regime, assuming daily discharge to 50% and full time voyaging:
Fully charged after each discharge. Estimated life: 6-9 Years."
Quote:
Originally Posted by skipmac
If I may ask, what do you see as the benefits to AGM batteries over FLAs? .... Most of the posts from member recommending AGMs ...don't seem to have enough capacity to take full advantage of the AGM's ability to take a higher rate of charge than FLAs.
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Let me keep this very short and not write a book.
With AGMs you don't need a high current source to charge faster, but if you do the rate up charge up to Absorption can be very much faster.
The main advantage of AGMs is the faster charging rate due to the Coulombic efficiency, or Charge Efficiency of AGMs. Battery Charge efficiency is different to Charge Acceptance Rate, but it is a subject not often explained or understood. MaineSail is the only person I know who would TRY and measure it!!!!
Charge Acceptance Rate is the amount of current that a battery will accept at a given voltage and given state of charge. AGMs will accept much more current than Flooded Lead Acid batteries without overheating the plates. This means that you can happily put more than 100 amps into a 100 Ah Lifeline AGM battery, whereas Trojan only recommend 10 amps, so Lifelines can charger very much faster than Trojans or similar FLAs.
Battery Charge Efficiency is how much of that current is actually converted to stored Ah. This is one of the values you have put into a good battery monitor to help it more accurately calculate the Ah stored in the battery. A typical default value is 85%. Wet Lead Acids can be anywhere from 70-85% and AGMs can be as high as 98%. Battery efficiency is very non-linear, so at 50% State of Charge it may be 95% for most batteries, but above 85% SoC it may be less than 50% which means with every 10Ah charged only 5Ah get stored. This gets much worse the closer to 100% SoC you get, which is why it takes so long to charge the last 2-3% of the battery SoC.
So if you want to store 100Ah in an FLA bank with an 80% Charge Efficiency then 125Ah has to be input. (80% of 125 is 100).
With an AGM bank at 98% efficiency then only 102Ah has to be input to raise the bank by 100Ah. That's 23% less Ah needed to raise the bank by 100Ah, so it is charging 23% faster. Lifeline claim 20% faster charge. This happens at all stages of the charge cycle with all rates of charge, so even a modest Solar Array will put more Ah into an AGM than an FLA bank.
And remember NOT ALL AGMs are created equal.
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21-01-2017, 11:17
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#50
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Registered User
Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 8,462
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Re: What batteries are you using and where are you buying them?
Quote:
With an AGM bank at 98% efficiency then only 102Ah has to be input to raise the bank by 100Ah. That's 23% less Ah needed to raise the bank by 100Ah, so it is charging 23% faster. Lifeline claim 20% faster charge. This happens at all stages of the charge cycle with all rates of charge, so even a modest Solar Array will put more Ah into an AGM than an FLA bank.
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Can you cite any sources for this information?
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21-01-2017, 12:10
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#51
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Registered User
Join Date: Mar 2012
Location: On board in Leros, Greece
Boat: Hunter Legend 420 Passage
Posts: 863
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Re: What batteries are you using and where are you buying them?
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21-01-2017, 18:18
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#52
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Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
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Re: What batteries are you using and where are you buying them?
Quote:
Originally Posted by sailinglegend
This came from Lifeline in my post #46.
"Justin Godber at Lifeline did define what expected battery life could be for their AGMs, depending on charge regime, assuming daily discharge to 50% and full time voyaging:
Fully charged after each discharge. Estimated life: 6-9 Years."
Let me keep this very short and not write a book.
With AGMs you don't need a high current source to charge faster, but if you do the rate up charge up to Absorption can be very much faster.
The main advantage of AGMs is the faster charging rate due to the Coulombic efficiency, or Charge Efficiency of AGMs. Battery Charge efficiency is different to Charge Acceptance Rate, but it is a subject not often explained or understood. MaineSail is the only person I know who would TRY and measure it!!!!
Charge Acceptance Rate is the amount of current that a battery will accept at a given voltage and given state of charge. AGMs will accept much more current than Flooded Lead Acid batteries without overheating the plates. This means that you can happily put more than 100 amps into a 100 Ah Lifeline AGM battery, whereas Trojan only recommend 10 amps, so Lifelines can charger very much faster than Trojans or similar FLAs.
Battery Charge Efficiency is how much of that current is actually converted to stored Ah. This is one of the values you have put into a good battery monitor to help it more accurately calculate the Ah stored in the battery. A typical default value is 85%. Wet Lead Acids can be anywhere from 70-85% and AGMs can be as high as 98%. Battery efficiency is very non-linear, so at 50% State of Charge it may be 95% for most batteries, but above 85% SoC it may be less than 50% which means with every 10Ah charged only 5Ah get stored. This gets much worse the closer to 100% SoC you get, which is why it takes so long to charge the last 2-3% of the battery SoC.
So if you want to store 100Ah in an FLA bank with an 80% Charge Efficiency then 125Ah has to be input. (80% of 125 is 100).
With an AGM bank at 98% efficiency then only 102Ah has to be input to raise the bank by 100Ah. That's 23% less Ah needed to raise the bank by 100Ah, so it is charging 23% faster. Lifeline claim 20% faster charge. This happens at all stages of the charge cycle with all rates of charge, so even a modest Solar Array will put more Ah into an AGM than an FLA bank.
And remember NOT ALL AGMs are created equal.
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Yes, I am aware of the potential for AGMs to accept a higher rate of charge and did mention that in my question. My point is, most boaters that have AGMs don't seem to have the ability to take advantage of the higher charge rate.
The charge efficiency however is not a point that has previously been brought into the discussion and to me might be one of the strongest arguments for AGMs.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
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26-01-2017, 15:56
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#53
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Registered User
Join Date: Dec 2016
Posts: 254
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Re: What batteries are you using and where are you buying them?
Of possible interest, here is a graph I pulled together recently to look at the lifespan of FLA vs AGM. The data came direct from the manufacturer datasheets.
Allan.
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26-01-2017, 16:17
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#54
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Registered User
Join Date: Apr 2013
Location: Everywhere (Sea of Cortez right now)
Boat: PSC Orion 27
Posts: 1,377
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Re: What batteries are you using and where are you buying them?
Quote:
Originally Posted by Peregrine1983
Thanks very much Skipmac. I'll give those a read. Very cool that you have a 422... beautiful boat!
Sounds like t-105's are the way to go for the house. I'm pretty budget conscious and the agm's are giving me sticker shock.
Now I've got to find some gc batts in the New York area.
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Trojan also makes a t-125 that's the same physical size as the 105s, worth checking the cost difference. They're what I'm using, charged by two one hundred watt panels.
goat
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26-01-2017, 17:51
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#55
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Registered User
Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 8,462
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Re: What batteries are you using and where are you buying them?
In this article by Maine Sail it took only 12 minutes longer to charge an AGM battery to 100% SOC at .2c charge rate than at .4c charge rate. He goes on to scale that up and there is not a huge difference in time at the two different rates. He comments that it takes a very large alternator to charge a typical house battery bank at .4c so the typical cruiser will probably compromise on the charge rate with not a large detriment to the time required to charge. The beauty of combining alternator and solar array is that the alternator can supple the bulk current at the beginning of the charge cycle and the solar can top off the charge. It took approx. 5.5 hrs to completely charge the AGM battery at .4c charge rate. Probably not a huge time saving over charging an FLA battery to 100% SOC.
How Fast Can an AGM Battery Be Charged..? Photo Gallery by Compass Marine How To at pbase.com
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27-01-2017, 03:28
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#56
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Registered User
Join Date: Mar 2012
Location: On board in Leros, Greece
Boat: Hunter Legend 420 Passage
Posts: 863
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Re: What batteries are you using and where are you buying them?
Quote:
Originally Posted by DeepFrz
.....It took approx. 5.5 hrs to completely charge the AGM battery at .4c charge rate. Probably not a huge time saving over charging an FLA battery to 100% SOC.....
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I wish MaineSail would do an FLA test - that's the comparison that's needed!!!! I'm sure and FLA at 0.2C will take much longer to exit Bulk than 1 hr 16 mins because it will not accept as much current as AGMs. Beyond this point you don't want to run a genny or an engine anymore anyway, let Solar or Wind take over.
Also I believe his test is NOT a real world test where the charger would have dropped to Float and the time to 100% would have been even longer, and may have been even closer!
I really respect all that his is doing, but this test seems a bit misguided without the comparison with FLAs.
Because the overall time to 100% is so long it's not surprising that there is little difference between 0.2C and 0.4C. But look at the results carefully and the key figures in the test are the times to exiting Bulk which are dramatic.
1 50% SOC to 100% SOC at .2C = 5:42 - Exited Bulk Charge at 1:16
2 50% SOC to 100% SOC at .4C = 5:30 - Exited Bulk Charge at 19 Minutes
0.2C is the maximum an FLA should be charged at, Trojan recommend 0.10 to 0.13C for FLAs. 0.2C is a minimum for AGMs.
0.4C is a minimum for TPPL AGMs. Lifeline AGMs are happy at a value at 1.3xC.
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27-01-2017, 03:59
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#57
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Senior Cruiser
Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43 and OPBs
Posts: 12,888
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Re: What batteries are you using and where are you buying them?
Quote:
Originally Posted by sailinglegend
1 50% SOC to 100% SOC at .2C = 5:42 - Exited Bulk Charge at 1:16
2 50% SOC to 100% SOC at .4C = 5:30 - Exited Bulk Charge at 19 Minutes
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The thing that I found interesting was:
At .4C the battery attained absorption voltage at approx 63.3% SOC and at a .2C charge rate it attained absorption voltage at approx 77.4% SOC
I guess that's because the higher charge rate results is a higher surface charge and it's this 14.4V surface charge that triggers the switch to absorption.
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27-01-2017, 04:05
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#58
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Registered User
Join Date: Mar 2012
Location: On board in Leros, Greece
Boat: Hunter Legend 420 Passage
Posts: 863
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Re: What batteries are you using and where are you buying them?
Quote:
Originally Posted by sailinglegend
....I really respect all that his is doing, but this test seems a bit misguided without the comparison with FLAs.
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I don't normally comment on my own posts but I wanted to add something but could not edit my post.
It would have been interesting for HIS comments on the results in the real world. I think this shows a couple of very interesting points. Doubling the size of the charger will not mean this will charge a 100Ah battery faster overnight if you go into a marina at 2000hrs at leave at 0800 hrs. It also shows that if you had a 400Ah battery it would take 24 hrs in a marina - so you will always need two nights!
All this also goes to support his messages that getting to 100% takes a VERY long time, which is why you can NEVER get to 100% every day with Solar alone.
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27-01-2017, 04:18
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#59
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Senior Cruiser
Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43 and OPBs
Posts: 12,888
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Re: What batteries are you using and where are you buying them?
Also, a word of warning on Main Sails numbers. His graph on Page 3 and his conclusion that it took over 7 hours to reach 100% SOC is wrong. He starts at 01:00 and finishes at 07:08. Absorption took 4.24 not the 5.24 that he states and total time was 6.08, not his 7:08.
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27-01-2017, 04:26
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#60
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Registered User
Join Date: Aug 2012
Location: Maryland, USA
Boat: 58' Sedan Bridge
Posts: 5,418
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Re: What batteries are you using and where are you buying them?
Quote:
Originally Posted by ayates
Of possible interest, here is a graph I pulled together recently to look at the lifespan of FLA vs AGM. The data came direct from the manufacturer datasheets.
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Which Liefline AGM battery was that? Exactly equivalent to the Trojan L16?
-Chris
__________________
Chesapeake Bay, USA.
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