would you buy used AGMs? - Page 2 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance > Electrical Systems
 Not a Member? 


Like Tree1Likes
Reply
 
LinkBack Thread Tools
  #11  
Old 04-18-2014
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,442
Thanks: 1
Thanked 76 Times in 74 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: would you buy used AGMs?

rm-
Like Maine said, not without a load test. Its like buying somebody's leftover pizza without being able to look in the box. (Or as they used to say, a pig in a poke.) If the guy is local to you, doing a test may be no problem and you may find a bargain. Lifeline makes a top quality product, if it was not abused.

Costco's battery policy apparently depends on the store manager. There's no uniform stock, and at least at the stores (plural) I've called, no one will check inventory, you have to simply go in and see what they have. A most peculiar and lousy way to do business, most unlike Costco, but that's what I've seen again and again, not just at one store. You'd figure in this day and age you could at least "order now and pickup when it arrives" the same way they sell tires, but no, you can't do that either.

But it could be worth talking to the seller, odds are he'll get very few offers and he'll be open to discussion.
Reply With Quote Share with Facebook
  #12  
Old 04-18-2014
TakeFive's Avatar
If it's blowin' I'm goin'
 
Join Date: Oct 2009
Location: Swarthmore, PA
Posts: 2,446
Thanks: 4
Thanked 41 Times in 39 Posts
Rep Power: 5
TakeFive will become famous soon enough
Re: would you buy used AGMs?

Quote:
Originally Posted by hellosailor View Post
rm-
Like Maine said, not without a load test...
Maine suggested a 20 hour capacity test. A "load test" is a very different thing, as it is meant to simulate the high current draw of a car/truck's starter battery. These batteries could easily pass the latter, yet fail the former.
__________________

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

Formerly posted as "RhythmDoctor"
1998 Catalina 250WK Take Five (at Anchorage Marina, Essington, on the Delaware River)
1991 15' Trophy (Lake Wallenpaupack)
1985 14' Phantom (Lake Wallenpaupack)
Reply With Quote Share with Facebook
  #13  
Old 04-18-2014
Senior Member
 
Join Date: Feb 2010
Location: Narragansett Bay
Posts: 8,695
Thanks: 10
Thanked 113 Times in 107 Posts
Rep Power: 6
Minnewaska will become famous soon enough Minnewaska will become famous soon enough
Re: would you buy used AGMs?

Non starter for me, capacity test or not. I'm not buying used batteries for anything other than a tag sale deal. Who knows how they were treated, charged, deep discharged, etc. Free or an inconsequential amount of money at best.

Also, while I'm no expert (some of this stuff gives me a headache), I learned enough about switching to AGMs a couple of years back, that I skipped it. The alternator and charger upgrades were simply prohibitive to me. Any advantage did not justify. You can burn out an alternator, if your system is not set up to charge AGMs. That would be an expensive bummer for buying discount used AGMs.
__________________

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

Jeanneau 54DS

In the harsh marine environment, something is always in need of repair. Margaritas fix everything.
Reply With Quote Share with Facebook
  #14  
Old 04-18-2014
Senior Member
 
Join Date: Jan 2010
Location: Boston, MA
Posts: 521
Thanks: 1
Thanked 1 Time in 1 Post
Rep Power: 5
rmeador is on a distinguished road
Re: would you buy used AGMs?

Well, you seem to have done a pretty good job of swaying me towards new flooded cell batteries. Regarding the gel vs flooded, from what I've read, gel batteries have many of the advantages of AGM (sealed, maintenance free, etc), with far fewer of the drawbacks (less damaged by deep draw, less demanding charging). So that's why I'm still willing to entertain the idea of them. If I buy new batteries, they'll almost certainly be flooded cell. I guess I better go check Costco and Sams Club. Thanks for the help!
__________________
1979 Gulfstar 37 Laissez Faire
Reply With Quote Share with Facebook
  #15  
Old 04-18-2014
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,276
Thanks: 9
Thanked 114 Times in 83 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
Re: would you buy used AGMs?

Quote:
Originally Posted by rmeador View Post
Well, you seem to have done a pretty good job of swaying me towards new flooded cell batteries. Regarding the gel vs flooded, from what I've read, gel batteries have many of the advantages of AGM (sealed, maintenance free, etc), with far fewer of the drawbacks (less damaged by deep draw, less demanding charging). So that's why I'm still willing to entertain the idea of them. If I buy new batteries, they'll almost certainly be flooded cell. I guess I better go check Costco and Sams Club. Thanks for the help!
GEL and flooded deep cycle also out-cycle AGM.... GEL does require lower charge voltages though so like AGM you still need to be set up for it. I have one bank of GEL's going into their 15th year this spring the only other bank that has even come close to that cycle life is Rolls 5000 series but these are MASSIVE batteries...............
__________________
______
-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.


Reply With Quote Share with Facebook
  #16  
Old 04-18-2014
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,276
Thanks: 9
Thanked 114 Times in 83 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
Re: would you buy used AGMs?

Quote:
Originally Posted by TakeFive View Post
I have no direct experience with marine AGM (I do have them on my Prius accessory battiries), so take my advice with a huge grain of salt (preferably Lead Sulfate lol):

Oddly enough the ONLY thing, that is non-routine maintenance, that has gone wrong with my Prius in 140K is the AGM accessory battery and it is now about ready again...... Nothing but the AGM accessory battery has failed on that car.

My wife's car, with 170K, still has the factory original flooded Honda battery that is now 8 years old........
__________________
______
-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.


Reply With Quote Share with Facebook
  #17  
Old 04-18-2014
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,442
Thanks: 1
Thanked 76 Times in 74 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: would you buy used AGMs?

Five-
"Maine suggested a 20 hour capacity test. A "load test" is a very different thing, as it is meant to simulate the high current draw of a car/truck's starter battery."
Not at all. The common load test that you are talking about uses a high load for a short time. A 2-hour capacity test uses a lower load for a longer time, but it is still a LOAD TEST used to measure capacity.
That might be different jargon to a power engineer, but in plain English, they're both load tests, just using different sized loads for different times.
Reply With Quote Share with Facebook
  #18  
Old 04-18-2014
TakeFive's Avatar
If it's blowin' I'm goin'
 
Join Date: Oct 2009
Location: Swarthmore, PA
Posts: 2,446
Thanks: 4
Thanked 41 Times in 39 Posts
Rep Power: 5
TakeFive will become famous soon enough
Re: would you buy used AGMs?

Quote:
Originally Posted by hellosailor View Post
Five-
"Maine suggested a 20 hour capacity test. A "load test" is a very different thing, as it is meant to simulate the high current draw of a car/truck's starter battery."
Not at all. The common load test that you are talking about uses a high load for a short time. A 2-hour capacity test uses a lower load for a longer time, but it is still a LOAD TEST used to measure capacity.
That might be different jargon to a power engineer, but in plain English, they're both load tests, just using different sized loads for different times.
My point was that if OP takes his battery into a battery dealer and asks for a "load test," he will likely walk out with the wrong information. Like you said, the short duration 100-amp load test is the "common load test." If he decides to find someone to test the used batteries for him, he MUST be specific in asking for a "20 hour capacity test."

I agree that both tests involve a "load" in the electrical sense of the term. But the nature of that load is very different in the two tests.

I have never heard of a "2-hour capacity test". I thought that the industry standard was a 20 hour test. You can choose to drain the whole battery in 2 hours if you want to, but you may have difficulty comparing this result with the battery's original 20 hour rating, which is what you need to do to assess whether the battery has been abused by the first owner.

I think jargon is important in this case. These words are not inconsequential - they have real meaning that affect the test conditions, and thus the test results.
__________________

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

Formerly posted as "RhythmDoctor"
1998 Catalina 250WK Take Five (at Anchorage Marina, Essington, on the Delaware River)
1991 15' Trophy (Lake Wallenpaupack)
1985 14' Phantom (Lake Wallenpaupack)

Last edited by TakeFive; 04-18-2014 at 10:17 AM.
Reply With Quote Share with Facebook
  #19  
Old 04-18-2014
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,276
Thanks: 9
Thanked 114 Times in 83 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
Re: would you buy used AGMs?

Quote:
Originally Posted by hellosailor View Post
Five-
"Maine suggested a 20 hour capacity test. A "load test" is a very different thing, as it is meant to simulate the high current draw of a car/truck's starter battery."
Not at all. The common load test that you are talking about uses a high load for a short time. A 2-hour capacity test uses a lower load for a longer time, but it is still a LOAD TEST used to measure capacity.
That might be different jargon to a power engineer, but in plain English, they're both load tests, just using different sized loads for different times.
A carbon pile load test tells you nothing about the actual Ah capacity of the battery. It is a short duration "impulse" or cranking amp test but does nothing to tell you how many Ah's your battery can deliver over long durations at lower loads. It is an utterly useless test in terms of knowing anything about the physical capacity of cycling banks. If you need to know the battery can start your Camaro then ok, but for cycling banks, a useless test unless looking for dead/alive but capacity unknown.

I have batteries that pass carbon pile tests with flying colors that have lost 30% + of actual Ah capacity. I have tested 100Ah batteries that pass a carbon pile test that come in at just 60Ah's of capacity...

The only accurate way to know if a battery has lost Ah capacity is to do a controlled 20 hour test or a reserve capacity (RC) test which is a 25A load for the batteries rated minutes.

All a typical "load test" tells you is if the battery can start an engine, which is easy.

A 20 hour capacity test is a 20% of "C" as a load until the battery hits 10.5V and you count Ah's delivered during this test or count time. Counting Ah's and using a relay to terminate the load at 10.5V is much easier.

or

25A for XXX rated minutes or until battery voltage hits 10.5V - count minutes before battery hits 10.5V. This requires human attention for the duration and with used batteries may not always translate as well to house bank loads, which are usually closer to the 20 hour rate...

If the battery is rated at 5 hours or 10 hours these can also be tested and the test is shorter but the amperage higher..

Controlled capacity tests are not easy and you need the equipment to do it, which most boaters don't have nor do typical battery shops........ Concord battery will happily sell you a tester for $3000.00 plus dollars but they are optimized for the aircraft tests which is a different rate.....

The Midtronics/impedance analyzers come closest on FLA batteries but do not work as well on GEL or AGM to translate to actual Ah capacity. They more closely correlate however than does a carbon pile test.

20 Hour Capacity Test - 100Ah Battery:

#1 Battery allowed to warm to 75F to avoid temp compensation calculations and mimic factory testing. I set my testing room at 75F to make this easier.

#2 Battery charged to full & current allowed to fall to 0.5% of "C" at 75F and rated absorption voltage. This is 0.5A at 14.XV for what ever the particular battery requires..

#3 Ah/Coloumb counter reset to 0.

#4 A load of 5A is applied to the battery and this 5A load is held constant (requires manual manipulation to maintain 5A as terminal voltage falls) or a custom built adjustable load cell.. The test load applied to the battery is determined by: Rated Ah capacity divided by 20 or 100Ah/20=5A. A 225Ah battery would be 225Ah/20=11.25A load.

#5 Test load is terminated once battery terminal voltage hits 10.5V

#6 Record Ah's delivered and compare to the factory rated 20 hour capacity. If you lack an Ah counter you count hours & minutes but this is very tedious....

#7 Recharge battery at 20 hour rate or a charge rate of 5A for a 100Ah battery or 11A +/- for a 225Ah battery....
TakeFive likes this.
__________________
______
-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; 04-18-2014 at 10:59 AM.
Reply With Quote Share with Facebook
  #20  
Old 04-18-2014
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,442
Thanks: 1
Thanked 76 Times in 74 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: would you buy used AGMs?

No, I wasn't getting a dealer involved in this at all. That means hauling lead to and from and back again, multiple trips and grunts. Nuh-uh. There's usually a way to scrounge a load and leave the batteries where they are. (Especially if they're still in the original owner's boat.) And really, even a shorter test with an intermediate load might be enough for the intended purpose, i.e. a couple of non-critical years on a specific boat.

As Chairman Mao said, "Black cat, white cat, all same, catch mice."
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
6V AGMs...any real alternatives to Lifelines? josrulz Electrical Systems 9 01-28-2012 12:00 PM
AGMs and standard alternators arf145 Electrical Systems 22 03-07-2010 06:56 PM
FullRiver AGMs gilsurf Gear & Maintenance 4 11-27-2007 03:17 PM
Northstar AGMs...anybody using them? Valiente Gear & Maintenance 21 08-21-2007 06:38 AM
Charging problem and AGMs kmclarke Gear & Maintenance 14 08-20-2007 12:28 PM


All times are GMT -4. The time now is 09:14 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.