Beneteau stock batteries or AGM upgrade?
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Hard to answer. First, why do you want AGMs? Second, are your local prices comparable if you bought them directly?
That seems VERY high for an upgrade. Seems high just for the batteries, never mind that should be the cost DELTA between the wet cells and the AGMs. How about deleting the stock batteries for credit and buying your own?
Don't know what your boating background might be and how conversant you are with boat battery/electrical systems. In general, wet cell batteries are the best bang for the buck and can take more abuse than other more exotic materials. If you go AGM, (which are pretty much unnecessary IMHO), please be aware of these issues:
AGM Battery Issues (from Maine Sail)
http://forums.sbo.sailboatowners.com/showthread.php?t=124973
AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
http://forums.catalina.sailboatowners.com/showthread.php?p=848465&highlight=darn agm
The prices you've been quoted are outrageous.
AGM Battery Issues (from Maine Sail)
http://forums.sbo.sailboatowners.com/showthread.php?t=124973
AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
http://forums.catalina.sailboatowners.com/showthread.php?p=848465&highlight=darn agm
The prices you've been quoted are outrageous.
I find the $800 fee expensive too and am not sure if this includes a credit for Beneteau's factory batteries. I am also unsure of the number of batteries included. The B41 comes standard wtih one engine 110AH and 2 house 110AH batteries. My boat also have an upgrade package with two more house batteries. I have a call with my salesperson to check.
Thanks to those who responded.
Thanks to those who responded.
If you have the choice, at least go for the extra batteries in the house bank, regardless of what type you choose. You'll end up doing it later anyhow, so get it right now. 
The price may include a high output aftermarket alternator. The AGM install should include one. The Beneteau house battery tray has limited space, so getting a high amp acceptance 220 Ah AGM is a great option. You can drain it lower and charge it 4 times faster than a similar sized flooded lead acid (which MAY provide 200 Ah)
No way! It's just the price of a battery "upgrade" although some might not call AGM's an upgrade! I had AGM's and don't think they're suitable for cruising. Went back to flooded batteries. AGM's like to be fully charged and that is difficult to do when cruising.
The standard Yanmar alternator isn't a good match for AGM use. Too little amperage at idle and cruise speeds.
Hi Gunni - My reasons for AGM on my 331 were, I had a weight distibution problem, so I slotted AGMs under my rear bunk, which fixed by list to port, AGMs do not need battery boxes. I could never have placed 400Ahs of battery in my port lazarrette. The boat sails way better now. AGMs as noted with Maine Sail (read everything he posts), over size your battery bank, the less you drain it during use, the longer it will last, and always fully charge after each use, upgrade your alternator, install battery monitoring system, andrade your shore charger. Not doing any of these, and you are wasting you $$
Running a Balmar 100 amp small case and smart regulator. Not a question of too little amperage and cruise speed. What the problem is is that when you're cruising you spend a lot of time at anchor. Batteries are usually discharged to 50% and when charging it just takes forever and is not economical to get the final 15% in. So you are using from 85% to 50 %. The batteries seldom get fully charged and AGM's don't like this. I switched back to flooded batteries and they are much better for cruising. If you're in a slip and on shorepower it really makes little difference what batteries you use but when cruising it makes all the difference.
Thanks Gordon, I'm actually looking at shrinking my house from 400Ah to 300Ah with a move to AGM.
Thanks Rick, I see your points. Wondering why you only spec'ed a 50% drawdown. AGMs are rated for drawdown to 35% - that is a big advantage - you can then dump large amperage, longer during charge. The reserve capacity for normal house draws are also much better.
I'm trying to lose one of my 4D's and get my batteries back to the original location. I do slip the boat, and I also have a genset that I would use with an upgraded battery charger to dump the large amperage the AGM battery can accept. If I was not in a slip I would definitely install a solar panel.
Believe I can get 300 Ah (2, 6vdc) AGM in the OEM battery location and with that get the extended drawdown to 35%, and at my 12 Ah drawdown the reserve capacity is 1200 minutes (a good 20 hours). I really like the power curve of the Electromaax 120 A alternator.
All this is still in the design stage - I just really want to shed 130lbs of battery in my locker.
Thanks Rick, I see your points. Wondering why you only spec'ed a 50% drawdown. AGMs are rated for drawdown to 35% - that is a big advantage - you can then dump large amperage, longer during charge. The reserve capacity for normal house draws are also much better.
I'm trying to lose one of my 4D's and get my batteries back to the original location. I do slip the boat, and I also have a genset that I would use with an upgraded battery charger to dump the large amperage the AGM battery can accept. If I was not in a slip I would definitely install a solar panel.
Believe I can get 300 Ah (2, 6vdc) AGM in the OEM battery location and with that get the extended drawdown to 35%, and at my 12 Ah drawdown the reserve capacity is 1200 minutes (a good 20 hours). I really like the power curve of the Electromaax 120 A alternator.
All this is still in the design stage - I just really want to shed 130lbs of battery in my locker.
Your bank should be ideally be sized the same whether you are installing AGM, GEL or WET lead acid batteries. With Li technology $$$$$$$ you can go smaller.
Wet cells can also be deeply cycled but common accepted depth for deep cycling is to not cycle the battery, whether AGM, GEL or WET to any deeper than 50%. The AGM makers all claimed that early on, and some still do, it was safe to go to 80% DOD, but when you cut through the marketing BS they all really recommend not cycling any deeper than 50%. Lifeline & Deka the two largest makers of AGM batteries used in the marine market both advise cycling to a max depth of 50% for the longest life.
Lifeleine: "For maximum battery life in cycling applications, do not discharge the battery bank below 50%."
Odyssey still advertises cycles to 80% DOD but when you look at the cycle curves it is clear 50% is better for them too. The term "deep cycle" refers to a depth of 80% and any deep cycle battery will do it but it then becomes how many times. I have yet to see many AGM batteries outlast basic wets in cycle life.
In bulk mode this is true and one great benefit of AGM batteries. You can go from 50% to 85% much faster than with wets but they still drastically limit charging at 80% SOC and beyond so getting to full is still just as elusive with AGM's as it is with wets if off cruising.
Being in a slip is very good for AGM batteries as they love to get back to full as often as possible.
Two 6V AGM batteries will get you about 220Ah. At a 12A load this gets you about 9 hours before hitting 50%. A 12A average load would be better served by a 450+ Ah bank..
I have installed quite a few of these and they are great but really benefit from the serpentine pulley kit when you get over 80A. I really like the 140A units over the 120A as they are not much more money and they can run for many hours at 120A+. They also pump out some large current at very low RPM.
130 pounds of weight in battery, on a large vessel such as yours, can be good weight if properly placed.
Thanks for checking in on this Maine. Can you comment on two manufacturer claims:
- A Lifeline AGM will produce more total Amp hours in it's life at 80% drawdown than it will at 30% drawdown. http://www.electromaax.com/faq/#q6
- An Electromaax 120A alternator will produce 100+A at high idle speed(1300 rpm). http://www.electromaax.com/wp-content/themes/electromaax/_common/pdf/120AmpSpecs_SM.pdf
That is just basic math but unfortunately skewed greatly by what I call non real world fantasy data. When AGM's first came on strong they too used lab derived data and pitched it as it would apply in the real world. It never does. I don't think I have seen many banks ever hit even 400 cycles in the real world let alone 2900 at 50% DOD or 1700 cycles at 80% DOD. For people who cycle to 80% DOD 1-2 seasons is more real world.. Going to 50% DOD then 5-6 years is more likely.
Think about it this way if those "fantasy" numbers were real and you swung on the hook 50 days per year, which is more than perhaps 90% of boat owners will ever do in a season, then you should be able to cycle to 80% DOD and still have the batteries last 1700 cycles / 50 cycles per year = 34 years of service. Not !!!!!
Please don't read into any of the "claims" of cycle life by manufacturers because they are not derived in the manner we use batteries, which is to abuse them, chronically undercharge them, stuff them in hot engine compartments etc. etc....
Cycling shallower does yield longer life and more Ah's when you use real world data not some white coat linen glove laboratory derived data. Odyssey is about as close as it gets to "realistic" in their claims of 400 cycles when used at 80% DOD. Even at 400 I would shoot from the hip and say that translates to about half or less than that in the real world..
I have been round and round with Rob & John on those curves. They SHOULD be based on alternator RPM not your engine RPM. They use a 2.25:1 ratio for that graph as they decided that was the most common ratio on marine engines. If you have less than 2.25:1 you will not get that output at 1300 engine RPM and if your ratio is higher than 2.25:1 you'll hit it earlier. They do pump out some serious current at low RPM.
On Monday morning of last week I fired up the motor after two nights on the hook. Bank was at roughly 70% SOC and is wet. When I went below to flip on instruments the alt was pumping 124A into the wet cell bank during the initial in-rush and it then tapered back to about 24-26% acceptance once the batts kicked back from the initial in-rush. These are six year old wet cells from Wal*Mart that cost me $210.00 for the entire bank.. Next summer will be year 7... The point is our 140A E-Maax (dumb regulated currently) was pumping out 124A at 1000 engine RPM.. If the banks would have taken it, it would have continued to produce some serious current.
When this bank finally dies I may experiment with AGM or Li technology... Unfortunately they are still going strong...
Great Scot! You are saying that marine-installed AGMs are missing their specified cycling claims by 800%. ...and their heat tolerance capability. I am prepared to manage for full-charge, but want no part of warranty squabbles.
Really don't care how many years beyond 7-8 a battery lasts. Two years would be completely unacceptable. Maybe I need to negotiate my own warranty terms with the battery company. I'm still pro-AGM...just looking for a reasonable deal.
Thanks, this kind of hands-on is invaluable.
Really don't care how many years beyond 7-8 a battery lasts. Two years would be completely unacceptable. Maybe I need to negotiate my own warranty terms with the battery company. I'm still pro-AGM...just looking for a reasonable deal.
Thanks, this kind of hands-on is invaluable.
AGM Nonsense
For about a year I have been thinking about this "Rush to AGMs" nonsense.
Why nonsense? Because Maine Sail (himself!) has documented the REALITIES of AGM use and charging requirements.
So, try this: you have a nice wet cell house battery bank, but end up going to AGMs because of the (unrealistic) promises. The most "attractive" is simply a quicker charge.
This, then, makes one consider the added requirements to support this new battery technology:
--- Bigger alternator with temperature sensing on both alternator AND house bank
--- Add an external regulator to control this
--- The unforeseen consequences of making this battery technology decision:
the NEED TO ASSURE that the bank is recharged both:
quickly and fully
--- This, then, requires a solar system if on a mooring or keeping your boat plugged in when you're not there (a whole separate subject but one which makes little sense)
So, you've ended up spending twice or thrice the cost of simple wet cells for maybe a half hour of difference of charging, but battery acceptance eventually takes over anyway
If it was my boat, I'd stick with wet cells. If you have "impossible" access, then (haha) get another boat with better access, or go gels.
Here, also, is why:
AGM Battery Issues (from Maine Sail)
http://forums.sbo.sailboatowners.com/showthread.php?t=124973
AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
http://forums.catalina.sailboatowners.com/showthread.php?p=848465&highlight=darn agm
Skippers, where we go with our boats, AGM makes little sense. Unless you really know what you're doing. Or are going seriously offshore. And even then, I'd go for wet cells. Why? 'Cuz you can buy them anywhere. Simple.
Good night and good luck.
For about a year I have been thinking about this "Rush to AGMs" nonsense.
Why nonsense? Because Maine Sail (himself!
) has documented the REALITIES of AGM use and charging requirements.So, try this: you have a nice wet cell house battery bank, but end up going to AGMs because of the (unrealistic) promises. The most "attractive" is simply a quicker charge.
This, then, makes one consider the added requirements to support this new battery technology:
--- Bigger alternator with temperature sensing on both alternator AND house bank
--- Add an external regulator to control this
--- The unforeseen consequences of making this battery technology decision:
the NEED TO ASSURE that the bank is recharged both:
quickly and fully
--- This, then, requires a solar system if on a mooring or keeping your boat plugged in when you're not there (a whole separate subject but one which makes little sense)
So, you've ended up spending twice or thrice the cost of simple wet cells for maybe a half hour of difference of charging, but battery acceptance eventually takes over anyway
If it was my boat, I'd stick with wet cells. If you have "impossible" access, then (haha) get another boat with better access, or go gels.
Here, also, is why:
AGM Battery Issues (from Maine Sail)
http://forums.sbo.sailboatowners.com/showthread.php?t=124973
AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
http://forums.catalina.sailboatowners.com/showthread.php?p=848465&highlight=darn agm
Skippers, where we go with our boats, AGM makes little sense. Unless you really know what you're doing. Or are going seriously offshore. And even then, I'd go for wet cells. Why? 'Cuz you can buy them anywhere. Simple.
Good night and good luck.
AGM's can still make sense but are a $$$ and systems commitment. I install lots of AGM batteries and they do help minimize engine run time when the "system" is well designed. Sadly many folks spend money on AGM's without taking advantage of the key benefits of the technology.
Those that expect longer life than deep cycle wets usually get pretty angry when they get the same or less use out of them and spent huge money on the bank and the upgrades. I try to give my customers an honest assessment of cost vs. benefit. In some cases it makes good sense and in others not so much.
The best value in an AGM technology today are the Duracell/Deka group 31's from Sam's Club for $166.00 each, but these are far from the best AGM's...
Those that expect longer life than deep cycle wets usually get pretty angry when they get the same or less use out of them and spent huge money on the bank and the upgrades. I try to give my customers an honest assessment of cost vs. benefit. In some cases it makes good sense and in others not so much.
The best value in an AGM technology today are the Duracell/Deka group 31's from Sam's Club for $166.00 each, but these are far from the best AGM's...
Thanks Maine, unfortunately the group 31 size doesn't fit my battery storage location - the tray in front of the engine. Two Odyssey PC 1800 batteries will fit, and would give me a +400 Ah house in a 4D footprint, but they are way expensive.
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