Practical Sailor AGM battery report - SailNet Community
 1Likes
Reply
 
LinkBack Thread Tools
post #1 of 13 Old 2 Days Ago Thread Starter
Senior Member
 
davidpm's Avatar
 
Join Date: Oct 2007
Location: Madison
Posts: 3,893
Thanks: 218
Thanked 58 Times in 50 Posts
Rep Power: 8
 
Practical Sailor AGM battery report

The latest issue of PS has a report on how real world usage affects AGM batteries.

The bottom line, (correct me if you got a different takeaway) was that standard cruising battery usage of discharging 50 to 60 percent then running the engine for an hour every day has the cumulative effect of diminishing the capacity of the battery significantly maybe 15% to 25%.

Bringing them up to full charge and equalizing seemed to restore the battery's capacity to some degree.

PS is sometimes accused of being too technical and missing real world effects.

I'm interested in what our experience members thing of this article.

Mainsail?

Also what is the deal with pulse chargers? They were not mentioned in the article.

The lesson from the Icarus story is not about human failing.
It is a lesson about the limitations of wax as an adhesive.
If you have an engineering problem solve it.
davidpm is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to davidpm For This Useful Post:
eherlihy (2 Days Ago)
Sponsored Links
Advertisement
 
post #2 of 13 Old 2 Days Ago
Less Senior Senior Member
 
Join Date: May 2011
Location: Bangor, Maine
Posts: 361
Thanks: 3
Thanked 23 Times in 23 Posts
Rep Power: 5
 
Re: Practical Sailor AGM battery report

Maine Sail wrote the article, and there is a thread on it from a couple weeks ago.

Ocean- that which covers 3/4 of a world made for man, who has no gills.
seaner97 is offline  
Quote Quick Reply Share with Facebook
post #3 of 13 Old 2 Days Ago
Senior Member
 
Join Date: Jul 2006
Posts: 1,216
Thanks: 1
Thanked 34 Times in 33 Posts
Rep Power: 9
 
Re: Practical Sailor AGM battery report

Interesting article in this month's 'Boat US' written by Ed Sherman, Director of Education Programing at ABYC that maybe of some interest...
aa3jy is offline  
Quote Quick Reply Share with Facebook
post #4 of 13 Old 1 Day Ago
Senior Member
 
night0wl's Avatar
 
Join Date: Mar 2006
Location: Fort Lauderdale
Posts: 1,454
Thanks: 0
Thanked 20 Times in 20 Posts
Rep Power: 10
 
Re: Practical Sailor AGM battery report

I thought you dont *EVER* equalize AGMs or other sealed batteries. No way to replace the fluid lost to boiling.

S/V Jendai
Beneteau 343
night0wl is online now  
Quote Quick Reply Share with Facebook
post #5 of 13 Old 1 Day Ago
Senior Member
 
Maine Sail's Avatar
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,789
Thanks: 18
Thanked 204 Times in 154 Posts
Rep Power: 16
       
Re: Practical Sailor AGM battery report

Quote:
Originally Posted by davidpm View Post
The latest issue of PS has a report on how real world usage affects AGM batteries.

The bottom line, (correct me if you got a different takeaway) was that standard cruising battery usage of discharging 50 to 60 percent then running the engine for an hour every day has the cumulative effect of diminishing the capacity of the battery significantly maybe 15% to 25%.
Absolutely but this is not anything new. The average sailor has NEVER achieved lab cycle numbers in the real world under PSOC cycling practice.

In a recent battery use survey on Sailboatowners.com with 1151 sailors answering the survey the average overnights spent on-board, where a deep discharge was likely to occur, shows that 89% of the respondents reported 35 nights or less per year with the vast majority 64% being 15 cycles or less.. It was also reported that 59% of all respondents got less than 5 years life from their batteries. This means 175 cycles on the high side and 75 cycles on the low side. This is a FAR CRY from the 1000-1200 cycles many battery makers claim in the LAB.....

Quote:
Originally Posted by davidpm View Post
Bringing them up to full charge and equalizing seemed to restore the battery's capacity to some degree.
Only the Lifelines could be equalized but in the end it still lost more capacity than the Odyssey TPPL AGM. Why? Hard to say without years more testing. It could however be because the Odyssey was allowed to achieve a higher charging voltage (14.7V vs. 14.4V). The Firefly was also charged at 14.4V but uses patented carbon foam on the grids to limit sulfation. Of course the Deka fell flat on its face and was charged to 14.6V so there are clearly quality differences between batteries but I suspect that the charging voltage does matter in PSOC.

Quote:
Originally Posted by davidpm View Post
PS is sometimes accused of being too technical and missing real world effects.
This test was specifically designed to MIMIC real world yet be repeatable and comparable between brands. The sad reality is that the battery industry refuses to give us a BCI test for PSOC tolerance. Sad and insulting really..

My gut suspicion is that a deep cycle AGM battery (Odyssey, Northstar & Lifeline) really need to get back to 100% SOC every 2nd or 3rd cycle for the best performance and longest cycle life. Ideally every cycle but that is simply not realistic.

It should be noted that the effects of sulfation happen to all lead acid batteries, not just AGM. AGM batteries are just much easier to test and to show how we are murdering our banks by how we use and abuse them. Flooded batteries can be charged at higher voltages on a regular basis and this can help limit sulfation and they can also be equalized.

The Firefly we know can go 30 deep cycles, with a full 100% recovery, but I suspect a full recharge ever 15-20 days is more reasonable for that battery.

Quote:
Originally Posted by davidpm View Post
I'm interested in what our experience members thing of this article.

Mainsail?
Seeing as I did the testing and wrote the article (though PS edited much of it and it was a lot of work in back & forth edits to make it accurate) I think you'll not find a more knowledgeable response on that testing...

Quote:
Originally Posted by davidpm View Post
Also what is the deal with pulse chargers? They were not mentioned in the article.
If you are talking about "battery desulfators" (I have also tested them) they are pure snake oil in regards to actually "desulfating" a sulfated battery. They may (strong emphasis on may) be of some slight benefit if starting new but I have seen batteries using them since new do no better than standard chargers, on a regular basis.

More about the testing:

Fighting Sulfation In AGM's - Practical Sailor May 2015

  • All batteries were treated exactly the same using lab grade test equipment and a temp controlled water-bath.
  • They were discharged and charged as we often do on boats thus replicating real world use in a "lab like" environment for closer A to B comparisons.
  • The Firefly was the only battery to survive the testing and recover all of its capacity. Other than the Lithium battery, which was used as a control or benchmark, the Firefly came out on top. PS's caution as "new technology" is certainly within reason, and I tend to agree with it, but the data still speaks rather strongly for the Firefly as a potential game changer for cycling applications on boats. No other AGM battery survived the 30 PSOC (partial state of charge) cycle testing without at least a 6-7% loss in capacity. The worst loss in capacity was approx 30% in just 30 PSOC cycles..
  • The way we use batteries on boats, partial state of charge operation, is murder to them so having a battery than can recover from the effects of sulfation could be a real game changer and far less complicated than LiFePO4.
  • In just 30 cycles some of the AGM batteries lost between 7% and 30% of their total baseline tested Ah capacity.. 7-30% capacity loss in just 30 cycles.. In the real world those 30 cycles would have likely been even more punishing, especially in a hot climate because the time between recharges would often be longer and allow the sulfate to harden more and risk less of it being re-convertible. In the test all batteries had to be treated equally and in the real world the time between discharge and partial recharge varies.
  • It also brings us to a question we did not delve into and that is; these batteries range in lab rated cycle life from 350 cycles to well in excess of 1000 cycles. What good are these lab numbers, and how realistic are they if we don't use our batteries in a lab like manner? The 350 cycle rated battery lost 30% or 1% for every PSOC cycle. Lab cycling tests are not PSOC which is how we use batteries in the real world. I can't talk about the second Deka battery we tested yet other than to say wait for the next issue......


My gut suspicion, after seeing this with my own eyes, is that a deep cycle AGM battery (Odyssey, Northstar & Lifeline) really need to get back to 100% SOC every 2nd or 3rd cycle for the best performance and longest cycle life, but we really already knew this. Ideally every cycle but that is simply not realistic on a boat..

It should be noted that the effects of sulfation happen to all lead acid batteries, not just AGM. The Firefly did form sulfate and lose capacity or "walk down" but it also fully recovered by the second deep cycle with full recharge.. AGM batteries are just much easier to test and to show how we are murdering our banks by how we use and abuse them. The effects of sulfation happen to ALL lead acid batteries, flooded AGM and GEL.

The Firefly we know can go 30 deep cycles, with full recovery, but I suspect a full recharge ever 15-20 days is more reasonable for that battery.

Interestingly the Firefly battery is sulfation recovered by discharging it to 10.5V - 11V then fully recharging it once or twice. This battery behaves entirely differently than other lead acid batteries when it comes to sulfation recovery and high voltages are not needed just deep discharges followed by a full recharge. I did not believe it myself until I saw and tested it. Two deep discharges with full recharges, back to back, results in the best recovery for the Firefly. This is due to the unique and patented carbon foam construction..



Quote:
Originally Posted by night0wl View Post
I thought you dont *EVER* equalize AGMs or other sealed batteries. No way to replace the fluid lost to boiling.
In general you don't equalize AGM batteries other than Lifeline brand AGM's.. Equalization can work on any lead acid battery but each AGM manufacturer has designed the battery for specific parameters and most have legitimate concerns about "drying" the battery out though equalization/gassing.

My own thoughts on the issue, after years of doing this, are that we destroy our batteries prematurely via sulfation, due to PSOC use, long before we'd ruin them with a periodic equalization.

I have cut open numerous dead AGM batteries only to find them still plenty "wet" but destroyed via sulfation. I suspect there is a fine line of absorption voltage vs. PSOC use but until the manufacturers study this, and tell us what that fine line is, for PSOC operation, we are only guessing at it to arrive at a suitable cycle life. I still default to the manufacturer's suggested guidance...

I can tell you that charging a certain manufacturers AGM 0.2V higher than recommended has resulted in longer cycle life in PSOC operation but I defer to the manufacturer for others doing the same.

The bottom line is that this is an answer best left to your battery maker. I do suggest using the highest allowable charging voltage you possibly can, as that tends to help fight off sulfation.


With most AGM batteries full means 0.5% - 0.3% current acceptance at absorption voltage before they can be considered "full". This is .5A to .3A of charge current acceptance, at absorption voltage, on a 100Ah battery and this can take 6 - 10+ hours to get there AT ABSORPTION VOLTAGE. When you have a charger or solar controller that uses an egg timer approach and times out of absorption at 2 or 4 hours.......????

Yep the problem is deeper than just PSOC.....

As I have said many, many, many times AGM or GEL batteries should be installed as a "system"....

______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




Images In Posts Property of Compass Marine Inc.



Last edited by Maine Sail; 1 Day Ago at 08:23 AM.
Maine Sail is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to Maine Sail For This Useful Post:
arisatx (1 Day Ago)
post #6 of 13 Old 1 Day Ago
Senior Member
 
Join Date: Sep 2014
Location: Northeast U.S
Posts: 381
Thanks: 5
Thanked 22 Times in 20 Posts
Rep Power: 1
 
Re: Practical Sailor AGM battery report

I've got two sets of batteries on board. Two Group 27 Gels making up the house bank and four 8A4D AGM in series making up a 48 volt propulsion bank. They were installed eight years ago and are still going strong. But, I charge them early and often using a Honda 2000 generator via well regulated battery charges and solar and a wind turbine (48 volt bank). Because I have electric propulsion for auxiliary power I have no alternator for charging. When motoring under electric propulsion when I see battery capacity has dropped to 70% from 100% that is when I fire up the Honda and start electro sailing. I usually stop drawing current from the battery at that point. At my destination I will use the generator to do a full charge on both banks. I use two chargers on the 48 volt bank. One for bulk series charging which get things up to around 94% charge capacity. I then switch to a Dual Pro 4 charger which charges each battery in the 48 volt string individually to full charge. After that solar and wind keep things topped up and no further charging via the Honda is usually needed. I'm aiming for ten years use out of the batteries and so far so good.
dj2210 likes this.

Mike
BIANKA: sailing the Isle of Long waters these days

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
mbianka is offline  
Quote Quick Reply Share with Facebook
post #7 of 13 Old 1 Day Ago
Senior Member
 
fallard's Avatar
 
Join Date: Nov 2009
Location: Mystic
Posts: 935
Thanks: 1
Thanked 12 Times in 11 Posts
Rep Power: 6
 
Re: Practical Sailor AGM battery report

Any idea how my Trojan AGMs compare to those in the PS article?
fallard is offline  
Quote Quick Reply Share with Facebook
post #8 of 13 Old 6 Hours Ago
Senior Member
 
Join Date: May 2002
Posts: 2,666
Thanks: 4
Thanked 28 Times in 26 Posts
Rep Power: 14
 
Re: Practical Sailor AGM battery report

I just bought a small gel for my 25' racer. It won't be used often or for long periods, mostly just when a race lasts after dark. I chose it because it's maintenance free.

Would it be better for the battery's longevity to recharge it after every use, even though it has only been used for an hour or two, or should I use it a couple times before recharging it?

Also, does anyone have any idea what percentage of it's charge can be expected to be lost just by sitting unused?

I want to be sure I charge it often enough so it powers my lights when I need them.
Sailormon6 is offline  
Quote Quick Reply Share with Facebook
post #9 of 13 Old 6 Hours Ago
Senior Member
 
Join Date: Dec 2012
Location: new england
Posts: 2,092
Thanks: 41
Thanked 40 Times in 37 Posts
Rep Power: 3
 
Re: Practical Sailor AGM battery report

Have 1020ah of lifeline house and separate lifeline start. Have solar and wind running 24/7. It's rare (once every several months) batteries drop to 80% and then run genset until they are back to float. In full cruising mode (radar,instruments, frig/freezer, AP all on) alt. energy keeps up. Boat is plugged in at a slip when not cruising for ~1wk/m. Boat is in operation except for bottom paint hauls.
After one year sensors (phillipi) tell me batteries at 980ah at float.
?Can I expect same annual decline in future years?
Would adding more alt. energy such as hydro generator prevent this?

s/v Hippocampus
Outbound 46
outbound is offline  
Quote Quick Reply Share with Facebook
post #10 of 13 Old 5 Hours Ago
Senior Member
 
Maine Sail's Avatar
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,789
Thanks: 18
Thanked 204 Times in 154 Posts
Rep Power: 16
       
Re: Practical Sailor AGM battery report

Quote:
Originally Posted by outbound View Post
Have 1020ah of lifeline house and separate lifeline start. Have solar and wind running 24/7. It's rare (once every several months) batteries drop to 80% and then run genset until they are back to float. In full cruising mode (radar,instruments, frig/freezer, AP all on) alt. energy keeps up. Boat is plugged in at a slip when not cruising for ~1wk/m. Boat is in operation except for bottom paint hauls.
After one year sensors (phillipi) tell me batteries at 980ah at float.
?Can I expect same annual decline in future years?
Would adding more alt. energy such as hydro generator prevent this?

The way you are treating your batteries should result in decent life. That said...

While the Phillipi is a very nice Ah counter it is still just an Ah counter. All the misinformation, programming errors, false resets etc. still apply. This device can not predict your Ah capacity or your Ah capacity loss. Anything it is showing you is 100% theoretical and usually not very accurate unless you've kept up with yearly Ah capacity tests etc., adjusted all the settings regularly and manually re-synced regularly.

The only way to know your true Ah capacity loss is to physically conduct a 20 hour capacity test. Of course if you did not start with a baseline Ah capacity then this % loss may not be precisely accurate but it will certainly give you the true Ah capacity at your batteries current life state..


I know this article is a LOT of information overload but do take the time to read it because it may give you a glimpse into how these magic boxes actually work..

Programming A Battery Monitor

______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




Images In Posts Property of Compass Marine Inc.


Maine Sail is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to Maine Sail For This Useful Post:
outbound (5 Hours Ago)
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 3 (1 members and 2 guests)
Triumphant
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Practical Sailor AGM Test, questions? BillB36 Gear & Maintenance 12 3 Weeks Ago 06:08 PM
Practical Sailor Kiltmadoc General Discussion (sailing related) 23 01-04-2011 06:18 AM
Sometimes Practical Sailor is NOT So Practical..? Maine Sail Gear & Maintenance 31 06-03-2008 01:04 PM
Practical sailor mag. ptsbug General Discussion (sailing related) 22 01-03-2007 06:04 PM
Sailnet and Practical Sailor sailaway21 General Discussion (sailing related) 1 12-03-2006 07:28 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome