I need to replace batteries on my Pearson 38 but not sure if I should go with AGM batteries or the flooded type I currently have. I am also looking to install additional batteries because my boat is currently on a mooring and I would like more juice from my batteries than always having to run the engine after only an hour of using lights and the radio.
Any thoughts?
I am also thinking of replacing the lights the boat originally came with for led lights to minimize on battery draw. Has anyone done this? Some insight would be great!
joe
Batteries-Flooded vs AGM and Gel
-
jerseyman26
- Bottom Sanding Grunt
- Posts: 9
- Joined: Mon Nov 01, 2010 11:31 pm
- Boat Name: LIfe's An Adventure
- Boat Type: 1990 Pearson 38'
Re: Batteries-Flooded vs AGM and Gel
Hi jerseyman,
I'm not sure I can give an answer, but I know I can ask more questions :) Since charging is such a system driven thing, here is what I'm thinking:
1) Have you laid out your "energy budget" to give you an idea of how much energy you are using (and therefore have to replace)? By that I mean, what is your average amp/hour usage per day? You can find this by seeing what each thing you have draws, and then guessing at how many hours per day it would be in use, and adding them all together (which you may already know).
2) Then, what sort of charging schedule do you (or could you) have? For example, do you go out for a week at a time but then come back and hit the shore charger? Do you go out for a month and rely on a solar panel or some other "trickle" type charging? Live on a mooring? Some of each? Something else? This might make a difference in whether you chose shore charging, wind generator, solar panels, generator, or a combination. And then that would make a difference in what type of batteries you might choose (for example for trickle charging and perhaps never quite getting them full, I might not choose AGM, etc.).
3) Lastly, how much room do you have? In some cases I like 6-volt golf cart batteries, but you need to use them in pairs and they are also slightly taller than most typical batteries.
I think if you tell us a bit more then it would be easier to make a recommendation.
Rachel
I'm not sure I can give an answer, but I know I can ask more questions :) Since charging is such a system driven thing, here is what I'm thinking:
1) Have you laid out your "energy budget" to give you an idea of how much energy you are using (and therefore have to replace)? By that I mean, what is your average amp/hour usage per day? You can find this by seeing what each thing you have draws, and then guessing at how many hours per day it would be in use, and adding them all together (which you may already know).
2) Then, what sort of charging schedule do you (or could you) have? For example, do you go out for a week at a time but then come back and hit the shore charger? Do you go out for a month and rely on a solar panel or some other "trickle" type charging? Live on a mooring? Some of each? Something else? This might make a difference in whether you chose shore charging, wind generator, solar panels, generator, or a combination. And then that would make a difference in what type of batteries you might choose (for example for trickle charging and perhaps never quite getting them full, I might not choose AGM, etc.).
3) Lastly, how much room do you have? In some cases I like 6-volt golf cart batteries, but you need to use them in pairs and they are also slightly taller than most typical batteries.
I think if you tell us a bit more then it would be easier to make a recommendation.
Rachel
-
Maine Sail
- Skilled Systems Installer
- Posts: 243
- Joined: Fri Feb 24, 2006 10:47 am
- Location: Casco Bay
- Contact:
Re: Batteries-Flooded vs AGM and Gel
My observations and experiences over the last few years have led me to some thoughts on AGM's and how the purchasing decisions are made. I see a lot of folks buy them based on either misguided advice or just for the wrong reasons based on how they use the boat or how they charge the bank. AGM's have some great benefits but are very expensive and are arguably less tolerant of abuse than wet cells.
Some scenarios that I have seen:
#1 Bought a 200-800 ah bank for their high acceptance rates then fed them with a 100 amp alt and 40 amp shore charger thus doing nothing to take advantage of this high acceptance "benefit".
#2 Bought them for the "low maintenance" then kept the boat on a mooring and ran the engine 35 hours a season. Even the worst wet cells, on the worst charger, won't boil off enough to matter on 35 engine hours per year.
#3 Bought them for low self discharge rates then left them sitting at 50% - 80% charged after each sail and killed them in three seasons.
#4 Bought them for the claimed "longer life" then found out they were dead in 4 seasons anyway, when the previous wet cells lasted 7.
#5 Bought them to replace wet cells that died a premature death, then the AGM's proceeded to do the same because the owner had refused to address his/her battery practices.
6# Bought them because they don't give off "gas fumes" when charging. The previous bank had zero signs of corrosion and in four years had never even taken water though they were due. When I opened them up they were still full and load tested at nearly new. Gave that bank to a friend who got two more seasons out of them. The new gasless AGM's died at year five.
#7 "The guy at West Marine said they were the best." He then proceeded to fry two stock alternators and finally had to buy a fully gourmet charging system for another 1.3k. Previous wet bank on dumb regulated alt lasted six years and cost $300.00 vs. $1000.00 + $1300.00 alternator regulator installation. $2300.00 vs. $300.00. I'll be surprised if he gets 6 years out of the Deka/WM AGM's (only on year two now).
I see and work on boats left on moorings, it's Maine, and the only thing I can ascertain is that AGM's do not like to sit discharged as mooring boats often do. I have seen lots of expensive AGM banks die before 5 seasons due to improper treatment. I also check date codes every time I am at my local battery & wire distributor on the core pallets. The 6 year old AGM core is a rather rare up here while the 6 & 7 year old wets are not all that uncommon on the pallet. Most of the dead AGM date codes are between 4 & 5 years at Dave's shop.
Nearly every boater I know with AGM's has bought them for their ability to take a fast charge then fed them with a diminutive alt that took no advantage of the high acceptance (wrong reason #1). I have personally seen a 100 Ah Lifeline take 85 amps for more than just a few minutes. I have yet to see any boater truly take advantage of the actual acceptance rates on a large bank because you'd need a HUGE alt to do so and small sailboat AUX engines just can't do this unless heavily modified to do so.
I replaced four T105's on a Sabre 362 that had lasted 7 years with a 90 amp dumb regulated alt. Boat resided on a mooring with no solar or wind. The Lifeline bank cost over $1400.00 and was flat dead going into the spring of what was to be their fifth season. At the same time we upgraded the batts a full gourmet charging system with 150 amp alt, dual pulleys, MC-612 Balmar regulator, temp sensing etc. etc. on and on was installed. He even bought a maintenance charger that was recommended by Lifeline tech support for the off season where they were stored in his 55 degree basement and cycled on and off the charger to keep them at 100% SOC. Total cumulative motor run time over the four previous seasons was just over 400 hours. The bank had never been discharged below 60% SOC during these four seasons as monitored by Link 20. They were just grave yard dead well before they should have been. Lifelines attitude, not out of the ordinary, try equalizing. He's back to 6V wet cells again, expensive experiment. This is one I really feel terrible about because at the time I had bought the AGM static hook line and sinker and really pushed this friend towards this set up. I have wracked my brain as to what cased this but there is no answer. Everything was done by the book except that he reside on a mooring so they were not always topped back up to 100%.
A few years ago I was chatting with John Harries of Morgan's Cloud about AGM issues. He has since written extensively on this issue and it is a good read and mirrors some of what I have seen:
http://www.morganscloud.com/2010/08/02/ ... st-part-1/
http://www.morganscloud.com/2010/08/10/ ... ry-test-2/
There is also my buddy who is the head systems tech at a very well respected boat yard here in Maine. He is an ABYC marine electrician, NEMA certified etc. etc. on and on and on. Probably one of the best marine guys I know in terms of knowledge. His own bank of AGM's in his own boat lasted three seasons (Deka's). He's gone to gel.
Don't get me wrong, there ARE benefits to them, and if you can truly take advantage of these benefits they can definitely be worth it. My only point here is that most I see don't truly take advantage of the benefits and I just want to promote some critical thinking before making a decision where you may spend $1000.00+++ that may not be even all that necessary, for a few weekends away from the dock.
What have I learned? If you go AGM try and keep them fully charged as best you can. If on a mooring get solar or wind to augment your alternator because and alternator alone no matter how fancy will not get them back to 100% SOC on a regular basis. If you can afford a $1000.00 bank you should really try to take care of them in terms of charging. In my opinion, and based on the "claims", these banks should have all easily gone 7+ years. While a few do, the reports I see and hear are nowhere near an average life of 7-10 years like the manufacturers initially claimed.
I had planned to go to AGM but I am still with wets because I have been able to live vicariously though others AGM trials and tribulations.
I suspect that if AGM's are left topped up, like if you are on a dock regularly, they can last as long as wets but I have yet to hear of many success stories where AGM's clearly out lasted good quality deep cycle wets which for the roughly 3X cost premium they certainly should. The original claims were many, many more cycles than wets.
Interestingly I have only topped up my bank of wets twice now in the last four seasons, took me all of three minutes each time. My wet cell bank cost me $240.00. The same bank in Lifelines would be about $1000.00. This is a $760.00 savings for 6 minutes work. That's really, really good pay to me...
I find this to be an interesting quote by Trojan Battery. When AGM's first came out the claims were BETTER cycle life than wets..
Quote From Trojan Battery:
For me the benefits of AGM rank in this order:
Higher acceptance - This is a HUGE benefit IF you can take advantage of it, many AGM equipped sailors I know physically can't take advantage of this feature.
Low self discharge - This is great for boats in hot climates or on moorings. Wets can self discharge at up to 13+% per month in warm weather however I know few boaters who go a month without using the boat at all. Even in a worst case scenario, 13%, in hot weather leaves a full bank still at 87% SOC after a month. Still this can be a good benefit in certain use situations. Self discharge has never been an issue for me so would not be weighed in my own benefit analysis.
Many boaters I know with AGM's also have either solar or wind making the self discharge benefit mostly irrelevant. The majority of boaters in the US are on docks not moorings so again self discharge would be of little benefit to them. When off cruising you are using the banks daily and self discharge is again a non issue. Most boaters have a phantom load such as a bilge pump, stereo memory or LPG detector etc. so there are already loads sucking the battery down that require periodic charging anyway which would take care of any self discharge at the same time. If you don't have solar or wind, are on a mooring, in a hot climate and rarely use your vessel this can certainly be a benefit.
Maintenance - I find this to be a tad over blown. I have yet to work on a vessel where it took me more than 20-30 minutes to add water to batts or check them and those are the long ones with major access issues. My own batts at 4 years old have taken water just twice now and it took all of about 3 minutes each time maybe four minutes at the outset if I got ADD..
If maintenance is the sole claimed reason for "upgrade", I know a boater who did this for that exact reason, it really is a lot of money to spend. He could have paid a pro to do the maintenance and still pocketed $400.00 to $500.00. Wet cell maintenance gets a little over blown IMHO and experience plus for very little money one can buy hydrocaps if really concerned.
Our batteries are dumb regulated and reside on a rather un-sophisticated solar charge controller yet they took a very small amount of water just twice in four years. I honestly don't even consider that "maintenance". Just checked them before winter and with my screw driver it took me all of 1 minute to glance at the water levels.
Even if I gave the water filling a ten minute labor allowance every year, at my $70.00 hourly rate, that is $11.60 worth of labor time. I would have to add water to my batteries 61 times over their life to equal the price premium on my bank to make the move to AGM based on maintenance alone.
Lay on side - This is usually much more of an issue on smaller vessels than large and folks with smaller vessels often won't spring for AGM's anyway. For about $40.00 in materials one can build a battery platform on just about any vessel. I have done them on nearly every boat I have owned for far less than the premium price upgrade to an AGM battery. You still have to find a way to secure them so you would possibly be looking at some epoxy work anyway.
I am not trying to dissuade anyone, because there certainly can be a benefit for many users. I just happen to see a lot of boaters not taking advantage of the actual reasons why they bought them in the first place, except for a couple minutes saved per year on maintenance and the occasional battery on its side.
Food for thought..
Some scenarios that I have seen:
#1 Bought a 200-800 ah bank for their high acceptance rates then fed them with a 100 amp alt and 40 amp shore charger thus doing nothing to take advantage of this high acceptance "benefit".
#2 Bought them for the "low maintenance" then kept the boat on a mooring and ran the engine 35 hours a season. Even the worst wet cells, on the worst charger, won't boil off enough to matter on 35 engine hours per year.
#3 Bought them for low self discharge rates then left them sitting at 50% - 80% charged after each sail and killed them in three seasons.
#4 Bought them for the claimed "longer life" then found out they were dead in 4 seasons anyway, when the previous wet cells lasted 7.
#5 Bought them to replace wet cells that died a premature death, then the AGM's proceeded to do the same because the owner had refused to address his/her battery practices.
6# Bought them because they don't give off "gas fumes" when charging. The previous bank had zero signs of corrosion and in four years had never even taken water though they were due. When I opened them up they were still full and load tested at nearly new. Gave that bank to a friend who got two more seasons out of them. The new gasless AGM's died at year five.
#7 "The guy at West Marine said they were the best." He then proceeded to fry two stock alternators and finally had to buy a fully gourmet charging system for another 1.3k. Previous wet bank on dumb regulated alt lasted six years and cost $300.00 vs. $1000.00 + $1300.00 alternator regulator installation. $2300.00 vs. $300.00. I'll be surprised if he gets 6 years out of the Deka/WM AGM's (only on year two now).
I see and work on boats left on moorings, it's Maine, and the only thing I can ascertain is that AGM's do not like to sit discharged as mooring boats often do. I have seen lots of expensive AGM banks die before 5 seasons due to improper treatment. I also check date codes every time I am at my local battery & wire distributor on the core pallets. The 6 year old AGM core is a rather rare up here while the 6 & 7 year old wets are not all that uncommon on the pallet. Most of the dead AGM date codes are between 4 & 5 years at Dave's shop.
Nearly every boater I know with AGM's has bought them for their ability to take a fast charge then fed them with a diminutive alt that took no advantage of the high acceptance (wrong reason #1). I have personally seen a 100 Ah Lifeline take 85 amps for more than just a few minutes. I have yet to see any boater truly take advantage of the actual acceptance rates on a large bank because you'd need a HUGE alt to do so and small sailboat AUX engines just can't do this unless heavily modified to do so.
I replaced four T105's on a Sabre 362 that had lasted 7 years with a 90 amp dumb regulated alt. Boat resided on a mooring with no solar or wind. The Lifeline bank cost over $1400.00 and was flat dead going into the spring of what was to be their fifth season. At the same time we upgraded the batts a full gourmet charging system with 150 amp alt, dual pulleys, MC-612 Balmar regulator, temp sensing etc. etc. on and on was installed. He even bought a maintenance charger that was recommended by Lifeline tech support for the off season where they were stored in his 55 degree basement and cycled on and off the charger to keep them at 100% SOC. Total cumulative motor run time over the four previous seasons was just over 400 hours. The bank had never been discharged below 60% SOC during these four seasons as monitored by Link 20. They were just grave yard dead well before they should have been. Lifelines attitude, not out of the ordinary, try equalizing. He's back to 6V wet cells again, expensive experiment. This is one I really feel terrible about because at the time I had bought the AGM static hook line and sinker and really pushed this friend towards this set up. I have wracked my brain as to what cased this but there is no answer. Everything was done by the book except that he reside on a mooring so they were not always topped back up to 100%.
A few years ago I was chatting with John Harries of Morgan's Cloud about AGM issues. He has since written extensively on this issue and it is a good read and mirrors some of what I have seen:
http://www.morganscloud.com/2010/08/02/ ... st-part-1/
http://www.morganscloud.com/2010/08/10/ ... ry-test-2/
There is also my buddy who is the head systems tech at a very well respected boat yard here in Maine. He is an ABYC marine electrician, NEMA certified etc. etc. on and on and on. Probably one of the best marine guys I know in terms of knowledge. His own bank of AGM's in his own boat lasted three seasons (Deka's). He's gone to gel.
Don't get me wrong, there ARE benefits to them, and if you can truly take advantage of these benefits they can definitely be worth it. My only point here is that most I see don't truly take advantage of the benefits and I just want to promote some critical thinking before making a decision where you may spend $1000.00+++ that may not be even all that necessary, for a few weekends away from the dock.
What have I learned? If you go AGM try and keep them fully charged as best you can. If on a mooring get solar or wind to augment your alternator because and alternator alone no matter how fancy will not get them back to 100% SOC on a regular basis. If you can afford a $1000.00 bank you should really try to take care of them in terms of charging. In my opinion, and based on the "claims", these banks should have all easily gone 7+ years. While a few do, the reports I see and hear are nowhere near an average life of 7-10 years like the manufacturers initially claimed.
I had planned to go to AGM but I am still with wets because I have been able to live vicariously though others AGM trials and tribulations.
I suspect that if AGM's are left topped up, like if you are on a dock regularly, they can last as long as wets but I have yet to hear of many success stories where AGM's clearly out lasted good quality deep cycle wets which for the roughly 3X cost premium they certainly should. The original claims were many, many more cycles than wets.
Interestingly I have only topped up my bank of wets twice now in the last four seasons, took me all of three minutes each time. My wet cell bank cost me $240.00. The same bank in Lifelines would be about $1000.00. This is a $760.00 savings for 6 minutes work. That's really, really good pay to me...
I find this to be an interesting quote by Trojan Battery. When AGM's first came out the claims were BETTER cycle life than wets..
Quote From Trojan Battery:
Not saying don't buy AGM's at all, just asking folks to think about why they are buying them, honestly.Generally, gel and AGM batteries have about 20% less capacity, cost about two times more, and have a shorter cycle life than comparable flooded lead acid batteries. However, Gel and AGM batteries do not need watering, are safer (no acid spilling out), can be placed in a variety of positions, have a slower self-discharge characteristic, and are more efficient in charging and discharging than flooded batteries (see table below). Gel batteries are more suitable for deep cycling applications whereas AGM batteries are more for light cycling and engine-starting applications.
For me the benefits of AGM rank in this order:
Higher acceptance - This is a HUGE benefit IF you can take advantage of it, many AGM equipped sailors I know physically can't take advantage of this feature.
Low self discharge - This is great for boats in hot climates or on moorings. Wets can self discharge at up to 13+% per month in warm weather however I know few boaters who go a month without using the boat at all. Even in a worst case scenario, 13%, in hot weather leaves a full bank still at 87% SOC after a month. Still this can be a good benefit in certain use situations. Self discharge has never been an issue for me so would not be weighed in my own benefit analysis.
Many boaters I know with AGM's also have either solar or wind making the self discharge benefit mostly irrelevant. The majority of boaters in the US are on docks not moorings so again self discharge would be of little benefit to them. When off cruising you are using the banks daily and self discharge is again a non issue. Most boaters have a phantom load such as a bilge pump, stereo memory or LPG detector etc. so there are already loads sucking the battery down that require periodic charging anyway which would take care of any self discharge at the same time. If you don't have solar or wind, are on a mooring, in a hot climate and rarely use your vessel this can certainly be a benefit.
Maintenance - I find this to be a tad over blown. I have yet to work on a vessel where it took me more than 20-30 minutes to add water to batts or check them and those are the long ones with major access issues. My own batts at 4 years old have taken water just twice now and it took all of about 3 minutes each time maybe four minutes at the outset if I got ADD..
If maintenance is the sole claimed reason for "upgrade", I know a boater who did this for that exact reason, it really is a lot of money to spend. He could have paid a pro to do the maintenance and still pocketed $400.00 to $500.00. Wet cell maintenance gets a little over blown IMHO and experience plus for very little money one can buy hydrocaps if really concerned.
Our batteries are dumb regulated and reside on a rather un-sophisticated solar charge controller yet they took a very small amount of water just twice in four years. I honestly don't even consider that "maintenance". Just checked them before winter and with my screw driver it took me all of 1 minute to glance at the water levels.
Even if I gave the water filling a ten minute labor allowance every year, at my $70.00 hourly rate, that is $11.60 worth of labor time. I would have to add water to my batteries 61 times over their life to equal the price premium on my bank to make the move to AGM based on maintenance alone.
Lay on side - This is usually much more of an issue on smaller vessels than large and folks with smaller vessels often won't spring for AGM's anyway. For about $40.00 in materials one can build a battery platform on just about any vessel. I have done them on nearly every boat I have owned for far less than the premium price upgrade to an AGM battery. You still have to find a way to secure them so you would possibly be looking at some epoxy work anyway.
I am not trying to dissuade anyone, because there certainly can be a benefit for many users. I just happen to see a lot of boaters not taking advantage of the actual reasons why they bought them in the first place, except for a couple minutes saved per year on maintenance and the occasional battery on its side.
Food for thought..
-
Chris Campbell
- Candidate for Boat-Obsession Medal
- Posts: 422
- Joined: Tue Jun 06, 2006 9:18 am
- Boat Name: Luna
- Boat Type: Yankee 30
- Location: Chester, NS
- Contact:
Re: Batteries-Flooded vs AGM and Gel
Excellent and thorough post, MaineSail - thanks.
I installed an 8D flooded (Rolls) in my last boat, and to combat the self-discharge I bought a $200 20W solar panel, which I would toss in a locker when I was sailing and put out on the lazarette when on the mooring. It would not only keep the battery from self-discharging, it would actually top it up so that I didn't need to worry about the last 10-20%. I never worried about shadows, despite it being a rigid polycrystalline panel (supposed to be shadow-sensitive) and located where there were some shadows at different times of day. The other amazing thing is that it would keep the battery topped up over the winter - with the panel under the white tarp! Remarkable, especially with short days in winter.
I will go the same route with this next boat since I had a good experience with it the first time and there is nothing in the advantages of either gel or AGM which appeal to my use of the batteries in my boat.
It is most certainly a personal decision, though - there are many variables!
I installed an 8D flooded (Rolls) in my last boat, and to combat the self-discharge I bought a $200 20W solar panel, which I would toss in a locker when I was sailing and put out on the lazarette when on the mooring. It would not only keep the battery from self-discharging, it would actually top it up so that I didn't need to worry about the last 10-20%. I never worried about shadows, despite it being a rigid polycrystalline panel (supposed to be shadow-sensitive) and located where there were some shadows at different times of day. The other amazing thing is that it would keep the battery topped up over the winter - with the panel under the white tarp! Remarkable, especially with short days in winter.
I will go the same route with this next boat since I had a good experience with it the first time and there is nothing in the advantages of either gel or AGM which appeal to my use of the batteries in my boat.
It is most certainly a personal decision, though - there are many variables!
-
jerseyman26
- Bottom Sanding Grunt
- Posts: 9
- Joined: Mon Nov 01, 2010 11:31 pm
- Boat Name: LIfe's An Adventure
- Boat Type: 1990 Pearson 38'
Re: Batteries-Flooded vs AGM and Gel
I want to thank everyone for their input. I have to conclude that AGM batteries are not worth the added expense. As I don't know the answer to any of Rachels' questions I do want to change my interior lights to LED to limit my draw as much as possible. Then add a solar panel somewhere even if it's only when at anchor.