Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 30-07-2015, 05:05   #1
Registered User

Join Date: Nov 2011
Location: St. Maarten
Boat: Amel Santorin, 46
Posts: 47
Switching from lead to AGM, anything to keep in mind?

Hi all, sorry if this is a regular question - I searched the archives but did not find an answer on it. So we are just now switching from 5 12V/100Ah Exide Excell lead batteries, to 5 12V/110Ah Victron Energy AGMs.

My question is: can I just remove the old batteries, plug the new ones in, adjust my battery monitor to 550 instead of 500 Ah, and I'm good to go? Or is there more that needs to be adjusted on the charging side?

Besides the 75 amp alternator on our Volvo Penta MD22 engine, we also have a 25 amp built in prop charger, a Tecsup Tecpro Charger Evolution II 25 amp battery charger that charges from shore power (it's an original from the 90s I believe), and two Victron regulators that come from our solar and wind respectively.

Our current lead batteries have usually charged up to just under 14.4 V, then when charged have run at around 12.7 V - all totally normal. These sound like the same levels recommended by Victron for the AGMs, but I want to make sure I'm not missing something.

All advice much appreciated. I'm so excited about these new "maintenance free" batteries, and want to see that they last a long time!

Cheers,
Patrick
__________________

__________________
PatrickG is offline   Reply With Quote
Old 30-07-2015, 05:17   #2
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,051
Re: Switching from lead to AGM, anything to keep in mind?

Have you bought the AGM's yet?
Do some reading, if you have the room, the golf cart batteries may, depending on your usage be a better choice.
Some people like me don't have much of a choice as our battery boxes won't accept the golf cart batteries.
But to answer your question, the charge profiles for an AGM is usually slightly different than a flooded cell battery. I assume flooded cell is what you meant by lead?
__________________

__________________
a64pilot is offline   Reply With Quote
Old 30-07-2015, 05:25   #3
Senior Cruiser
 
Vasco's Avatar

Cruisers Forum Supporter

Join Date: Apr 2004
Location: Toronto
Boat: CS36Merlin, "La Belle Aurore" Ben393 "Breathless"
Posts: 7,138
Re: Switching from lead to AGM, anything to keep in mind?

Quote:
Originally Posted by a64pilot View Post
Have you bought the AGM's yet?
Do some reading, if you have the room, the golf cart batteries may, depending on your usage be a better choice.
Some people like me don't have much of a choice as our battery boxes won't accept the golf cart batteries.
But to answer your question, the charge profiles for an AGM is usually slightly different than a flooded cell battery. I assume flooded cell is what you meant by lead?


I went to AGMs a few years ago. They lasted two seasons. Unless you can fully charge them frequently, AGMs are not the way to go for a cruising boat. I'm back to flooded now. Lots of posts on this issue. Do a search.
__________________
Rick I
Toronto in summer, Bahamas in winter.
http://groups.yahoo.com/group/beneteau393/
Vasco is offline   Reply With Quote
Old 30-07-2015, 06:08   #4
Registered User

Join Date: Nov 2011
Location: St. Maarten
Boat: Amel Santorin, 46
Posts: 47
Re: Switching from lead to AGM, anything to keep in mind?

Hi guys, thanks for the input. The batteries are bought and sitting in my cockpit right now. I bought them on the back of the experience of some tropical cruising friends who have them and love them. Sailed 8 years on their last set.

What would be great is further advice on the above question: do I need to make other adjustments to my charging system? And (oh boy) if so, any further experiences on doing that? Many thanks!

Cheers,
Patrick
__________________
PatrickG is offline   Reply With Quote
Old 30-07-2015, 06:13   #5
Registered User

Join Date: Nov 2011
Location: St. Maarten
Boat: Amel Santorin, 46
Posts: 47
Re: Switching from lead to AGM, anything to keep in mind?

PS this is the current battery type I've had: Exide 249se EB1004 Car Battery:Amazon.co.uk:Car & Motorbike
__________________
PatrickG is offline   Reply With Quote
Old 30-07-2015, 06:23   #6
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,051
Re: Switching from lead to AGM, anything to keep in mind?

I'm not familiar with your chargers, Ideally absorption time and voltage is adjustable as well as float voltage.
Get with the battery manufacturer and find out at least what they recommend for absorption and float voltage and ensure that is either adjusted to their recommendations or is very close to their recommendations, then ensure the voltage as measured at the battery are close.
For example my old charger was fine, but the long and undersized wiring to to batteries dropped the float voltage to just above 12V, so while the charger was OK, the poor installation made it un-acceptable.

From my limited understanding AGM's do not tolerate partial charging nearly as well as a flooded battery will, and to charge to 100% is difficult, but necessary for a long life out of AGM's
__________________
a64pilot is offline   Reply With Quote
Old 30-07-2015, 06:52   #7
Senior Cruiser
 
AfterHoursNLCT's Avatar

Cruisers Forum Supporter

Join Date: Nov 2010
Location: Quaker Hill, CT (just above the US Coast Guard Academy)
Boat: Silverton 34 Convertible
Posts: 191
Re: Switching from lead to AGM, anything to keep in mind?

Quote:
Originally Posted by Vasco View Post


I went to AGMs a few years ago. They lasted two seasons. Unless you can fully charge them frequently, AGMs are not the way to go for a cruising boat. I'm back to flooded now. Lots of posts on this issue. Do a search.
My neighbors on the dock had EXACTLY the same results and have switched back to flooded lead/acid...
__________________
AfterHoursNLCT is offline   Reply With Quote
Old 30-07-2015, 06:56   #8
Registered User
 
SimonV's Avatar

Join Date: Aug 2007
Location: Brisbane, Australia.
Posts: 1,316
Re: Switching from lead to AGM, anything to keep in mind?

You really need to increase your alternator size or reduce your bank into 2 separate banks or you will burn out your Alternator or have premature battery failure.
__________________
Simon

https://svgoodonya.blogspot.com.au/
SimonV is offline   Reply With Quote
Old 30-07-2015, 06:57   #9
Senior Cruiser
 
AfterHoursNLCT's Avatar

Cruisers Forum Supporter

Join Date: Nov 2010
Location: Quaker Hill, CT (just above the US Coast Guard Academy)
Boat: Silverton 34 Convertible
Posts: 191
Re: Switching from lead to AGM, anything to keep in mind?

Quote:
Originally Posted by PatrickG View Post
What would be great is further advice on the above question: do I need to make other adjustments to my charging system? And (oh boy) if so, any further experiences on doing that? Many thanks!

Cheers,
Patrick
I have a good article on my boat computer that I will post a link to when I get back there later today. Has all the information that you are looking for.
__________________
AfterHoursNLCT is offline   Reply With Quote
Old 30-07-2015, 07:10   #10
Registered User

Join Date: Apr 2006
Posts: 4,413
Re: Switching from lead to AGM, anything to keep in mind?

I have 2 8D agms and a couple of solar panels and a high 100 amp alternator w/ a smart regulator... on a mooring and they are always topped up and work a charm. No maintenance and plenty of power.
__________________
Sandero is offline   Reply With Quote
Old 30-07-2015, 07:24   #11
Registered User

Join Date: Jun 2012
Location: Port Aransas, Texas
Boat: 2002 Seawind 1000 (33 ft) Cat
Posts: 841
Re: Switching from lead to AGM, anything to keep in mind?

Patrick,

Earlier this year, I replaced the three original-equipment Deka 105 amp-hr AGM batteries on my catamaran. They were 12 yrs old when they finally crapped out. I replaced them with the same batteries. They were kept charged by both a solar MPPT controller, and a three-stage shore power charger. I didn't read the referenced "short life AGM" article, but just want to say my experience has been quite different.

Get a manual for your chargers. From what I remember, the charge level for AGM's is different than flooded cells. It was easy to reset.
__________________
sailjumanji is offline   Reply With Quote
Old 30-07-2015, 08:12   #12
Registered User

Join Date: Nov 2011
Location: St. Maarten
Boat: Amel Santorin, 46
Posts: 47
Re: Switching from lead to AGM, anything to keep in mind?

Quote:
Originally Posted by SimonV View Post
You really need to increase your alternator size or reduce your bank into 2 separate banks or you will burn out your Alternator or have premature battery failure.
Hi SimonV, can you please elaborate on that? Why would a 75A alternator burn out, when it was worked fine with 500 Ah of batteries, when just moving up to 550Ah total? One note here: I'm not planning on discharging these batteries more than 50% max ever. Is there some reason why the AGM batteries specifically could put too heavy a load on the alternator?
__________________
PatrickG is offline   Reply With Quote
Old 30-07-2015, 08:28   #13
Registered User

Join Date: Nov 2011
Location: St. Maarten
Boat: Amel Santorin, 46
Posts: 47
Re: Switching from lead to AGM, anything to keep in mind?

Thanks all for the further input - great to hear not all AGM experiences have been bad - AfterHoursNLCT would be super to read that article!

So I talked with Victron this afternoon and they were very helpful. They specified the float voltage at 13.8V and the absorption at 14.4V (they also talked about a "charge current" limit of 10-20%, which was a bit more mysterious, hmm...). I did not have a manual for that original battery charger, 18 years old, so I talked to the Tecsup folks (so lucky we live in the age of Internet and mobile phones) who immediately mailed me a manual. And lo and behold, while the charger is currently set to a different setting for the flooded lead batteries, and it predates the widespread use of AGM batteries, it does have one which perfectly matches the new batteries' specs. Great.

So now I'm going to check ditto for my solar and wind regulators.

Which just leaves the engine alternator, and the sail drive generator (which looks and acts very much like an alternator).

Follow-on question - does anyone have any idea if it's possible or necessary to adjust the float voltage coming out of an alternator like that? They don't seem so very adjustable. Or do they run on a basic one-size fits all approach?
__________________
PatrickG is offline   Reply With Quote
Old 30-07-2015, 08:41   #14
Registered User

Join Date: Jun 2012
Location: Port Aransas, Texas
Boat: 2002 Seawind 1000 (33 ft) Cat
Posts: 841
Re: Switching from lead to AGM, anything to keep in mind?

My guess is that alternator is not adjustable. But I am only running twin 9.9 hp Yamahas, so alternators not that big.

One thing I did want to pass along regarding the AGM's is that someone told me - or some place I read - that they need to be brought back to full charge at least once per week. Maybe someone else can back me up on that. The discussion was regarding whether the two solar panels I have could run the watermaker for a few hours and still have enough daylight left to get the batteries back up to full.

My AGM's might have lasted so long because it was rare that they didn't get back to full charge each day. At the dock, there is a 3-stage battery charger that does the trick. At anchor, our situation is that usually around noontime the two solar panels have the batteries back to full and on trickle only. We have a Blue Sky three-stage MPPT controller. FYI
__________________
sailjumanji is offline   Reply With Quote
Old 30-07-2015, 09:24   #15
Registered User
 
Russ's Avatar

Join Date: Jul 2008
Location: Montpelier,VT
Boat: Brewer 44' Steel
Posts: 151
Re: Switching from lead to AGM, anything to keep in mind?

For what it is worth my AGM''s (1,000 amps worth) lasted SEVEN Years. granted I am at a dock 4 months of the year when I leave sunny FL for not so sunny VT in the summer. That said, Flooded batts are fine and cheap IF you have the time and presence of mind to refill the water and not kill a cell . They are by comparison high maintenance.
For me leaving them unattended for 4 months was a deal breaker when my original lead acids died.
Also remember to change the batt type on your charger, AGM's don't tolerate Lead acid charging parameters. Russ
__________________

__________________
Russ
Russ is offline   Reply With Quote
Reply

Tags
agm

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not 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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mixing AGM and Lead Acid batteries CSY Man Electrical: Batteries, Generators & Solar 24 17-04-2015 19:26
lead acid / agm conversion dakno Electrical: Batteries, Generators & Solar 3 29-07-2014 19:03
Lead keel vertical cracks in lead Secondwave Construction, Maintenance & Refit 4 21-05-2013 09:50
AGM vs Sealed Lead Acid Battery stevensuf Electrical: Batteries, Generators & Solar 99 14-02-2013 12:05
If You Keep Your Boat on a Mooring these Tips Might Keep it Off the Rocks SailFastTri Anchoring & Mooring 16 06-07-2010 12:32



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 02:24.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.