Gel or Flooded?

[JBsurfin]

Originally Posted by a64pilot

So how often do you need to add water? I have AGM now and of course don’t, but I figure it’s a once a month task, I know how often will depend but still am under the impression that it’s once a month.
It’s value I’m trying to determine, Firefly for instance is I believe over $5 an AH, and to me that puts them way overpriced.

I go about 3 months to a refill, that's with using and charging daily.

[Retirecaribbean]

All,
I've been in the commercial battery biz for over 30 years. Properly maintained wet cells can go up to 30 years, AGM 10-15 years. BUT this all depends on how deep the discharge, the number of cycles, and recharge parameters, quality of lead, etc. I typically see flooded replaced every two years from neglect and poor charger parameters. So for a variety of reasons and in this situation, bite the bullet and buy lithium. I know $10/AH, but these batteries utilize almost 90% of their AH versus the rest utilize 50%, so figure $5/AH as you need half as many. A good AGM is $6/AH No you can't discharge 80% and expect the battery to last very long on AGM etc.

Battle Born is one vendor I like as it is user friendly as long as the charger/inverters are set properly and has a nice product that protects the battery with internal monitoring.

Thanks

[s/v Jedi]

Originally Posted by lituya1617

My 43-foot cruiser featured two 8D heavy equipment batteries and a Delco 65 amp automotive alternator (internally regulated). This setup lasted for ten years and the batteries were like new. The boat used a lot of power because a large freezer, many lights, a forced-air galley stove, and electronics. So, what is wrong with this old fashioned way of battery use?

That’s simply not possible. Even without cycling, batteries age and 10 years severely affects their usable capacity, even with LiFePO4.

[David Mathis]

How can one justify the added cost of gel or other premium batteries? My boat takes four group 27 batteries which consistently last five to seven years or more before showing any power reduction on the load tester. Once a year the electrolyte level is down to the point that water has to be added. The batteries are in an area that has good accessibility so checking them and adding water is easy. Since the refrigerator, freezer, ice maker, and other loads are all 110 ac and run on the generator, deep cycle batteries aren’t necessary although they are marine rated. When the batteries need replacement, I head to a discount store and save a third or maybe even half over the marina price. So, with that said, how could I justify spending three to five times as much or maybe more for premium batteries?

[Retirecaribbean]

Everyone's situation is different. You are not utilizing your batteries for AC loads. You have roughly 200AH of useable 12 volt power.

[GrowleyMonster]

Wow tough situation. I would say GC-2 flooded if you could squeeze them in there. Or raise up the settee by builting a 2" high extension. Think box, with no top or bottom. This may be a situation where you would want to put the batteries somewhere else altogether. Not knowing the layout of your boat, I don't have a clue, but good bets are right on the cabin sole in a DIY wooden enclosure taking the place of your companionway steps, or in the lazarette, or in the bilge in a high quality battery box. With of course an emergency backup battery for bilge pumps located somewhere high. Under the vee berth, maybe. Probably you have already exhausted all the options I don't know, but it is worth another look before you whip out the credit card.



Gels might last 3x longer than the average group 31 FLA, but definitely not 3x longer than properly maintained true deep cycle FLA, which as you know, most marine batteries are not. I got a good 7 years use out of my $85 golf cart batts from Sams Club, with very spotty maintenance. Neglect, actually, because I was often away at sea for up to 8 months at a time. I probably could have got another year out of them if I had been home to check on them at least monthly. This was a propulsion AND house bank, in an electric boat, BTW.



If you are willing to pay the premium for gel, you might consider LiFeP04, which seem a bit safer than ordinary LiIon batteries. I don't like them but plenty of people do.

[KP44]

I've said this before but maybe it is worth repeating…

I had three 8D size AGMs from West Marine. They were supposed to never leak. When I inspected them after a summer on the hard, two of the batteries had cracks and had leaked acid (or something). They were not beat up or dropped. The boat just sat there on stands for 8 months and the batteries destroyed themselves. I replaced them with eight 6-volt golf cart type batteries.

[Retirecaribbean]

battlebornbatteries.com

[CarinaPDX]

I started out by building three group 30H battery boxes into Carina, and installed three 30H Rolls batteries. Rolls were the best deep cycle FLA batteries at that time. They took about a cup of water per month (total) and worked very well. However, they did not provide a "stiff" enough voltage for some of my electronics. FLA batteries have a higher internal resistance than the other types so can neither charge or discharge at as high a rate - just a fact, but one not usually considered. In the OP's case his 800AH is so large that no one battery is charging/discharging at a high rate. But that is a heck of a lot of capacity for a 38' boat.

When the Rolls died I replaced them with three Sonnenschein Prevailer gel batteries (model 180, about a group 31 size). They noticeably outperformed the Rolls batteries (even though more than a third less capacity) as far as holding up voltage under load, and charge acceptance rates. In full-time cruising I got about 8 years out of them - and replaced with same. East Penn (Deka) had a technology and marketing agreement with Sonnenschein which brought the East Penn gels up to the same standards. IIRC Exide bought Sonnenschein and so has access to the same technology. Until Sonnenschein, gel batteries had issues with cracks in the gelled electrolyte that could greatly reduce performance. There were, and I believe still are, gel batteries that are unsuitable for our needs. If buying gels it is safest to stick with Sonnenschein and East Penn. Note that the Sonnenschein batteries have European standard terminal locations, which is opposite the US BCI locations, and might affect your wiring.

AGMs are more commonly available than gels but from my reading are not up to the same standards as gels, as well as being less tolerant of PSOC. Since the best AGMs are the same price as the best gels I see no reason to go that way. BTW top quality FLA batteries are not nearly as cheap as the OP says - a $100 group 31 is not anything like a quality deep cycle battery of the order of the Rolls.

Personally I am looking to install Firefly batteries soon. I am re-wiring the DC system so this is a good time to switch back to the BCI standards. The Firefly batteries appear to be a bit better than gels, as shown by the early adopters. Whether they will have the long life that is promised is still to be seen but so far so good. If not Fireflys then I would buy the East Penn gels.

For the bleeding edge early adopters lithium is very attractive, as long as the owner is willing to do the research and be his own technician, as well as have a pot of money burning a hole in his pocket... In most of the world knowledge and parts will be an issue if there is a failure, and hence the need for knowledge aboard. The advantage of a 12V lead acid system is that there will be batteries and chargers available everywhere, if less than ideal performance.

The OP states that he is using 150AH overnight. That is a lot of power consumption for a 38' boat. I recommend taking a close look at reducing consumption.

Greg

[rslifkin]

For AGM vs gel, AGMs tend not to last as long and are less tolerant of PSOC. But they tend to be better at supplying large bursts of current without excessive voltage sag, they'll typically accept higher charge current than gel and they're not quite as voltage sensitive, so if there are things like internally regulated engine alternators in the mix, it's easier to avoid cooking AGMs to death compared to gel.

[Retirecaribbean]

Haven't done much research on the firefly batteries but they appear to be lead acid and >$5/AH. Lithium is about $5/AH when you consider you need 1/2 as much AH in comparison. The biggest issue with any lead acid even if they say temp tolerant is that none of them do very well above 77 degrees. Lithium doesn't have that problem although they don't do well in the cold. Lithium is a very simple battery as long as they have a good battery management system built in to the batteries.

[Maine Sail]

Originally Posted by a64pilot

So is Gel worth three times or more cost? Will a group 31 Duracell (Deka) flooded battery last five years in actual use?

East-Penn / Deka rates their G-31 Flooded Deep Cycle at just 350 lab cycles
East-Penn / Deka rates their G-31 Gel at 1000 lab cycles

[CarinaPDX]

I have found that one of the most important rules in life is TANSTAAFL (There Ain't No Such Thing As A Free Lunch). Deep cycle batteries' prices tend to reflect quality/performance. A top quality flooded (Rolls, and some would say Trojan) grp 31 should be over $200, and weigh 65-70lbs. Top quality gels (Sonenschein Prevailer, Deka Dominator) and AGMs (Lifeline) are $400-500 and about the same weight. The Firefly carbon foam is $512. When considering that the flooded battery typically has half the warranty period, more maintenance required, and higher internal resistance (slower charging/more voltage sag under load) than the others it is hard to justify FLAs unless the boat will be sold in the next few years. While cheaper batteries might be used for local cruising I sure wouldn't want to be in the middle of the ocean with them. You may value things differently...

It is often said that golf cart batteries are a better deal; they are not if using top quality (e.g. Rolls, Trojans). They are more readily available, and perhaps better discounts can be found as a result, but they still play by the same rules.

For a 38' boat a bank of four group 31 gels or carbon foam should be adequate. But that implies investing in LEDs and eliminating incandescents completely, having a very well-insulated refrigerator with an efficient system (almost certainly a Danfoss), and other electronics also efficient. Of course it depends how long between charges, which in turn implies something about solar and/or wind charging underway. And to minimize run times a large alternator with smart regulator is desirable. It is a system problem, not just a battery one. Even with an efficient consumption I think $1500-2000 for the 4-battery bank is the right price range.

Greg

[Retirecaribbean]

Greg,
I agree with your comments, but considering that high temperatures (above 77 degrees) are the most damaging to batteries and my experience in the biz I would go with 200 AH of Lithium's which gives you the same amount of power for the $2000 and zero maintenance. Not to mention a 100 AH Lithium weighs roughly 30 lbs.

As for firefly I have no idea on any comparisons.

Cheers

[CarinaPDX]

Many of us have spent summers in the tropics with lead acid batteries with no obvious problems. It might result in shorter battery lives but that would be hard to know. In any event the tropical heat doesn't present a deal-breaker or result in catastrophic failure.

The OP wasn't asking about lithium. We have many threads about that here, and clearly lithium use among our members is growing, and for good reason. But lithium is not a simple drop-in replacement of batteries: it requires at a minimum a good battery management system, plus a certain amount of knowledge. Some day, probably not that far away, lithium will be a common, "normal" solution that is comfortable for the average person - but we are not there yet. Also, if being "green" matters to you, lead acid batteries have a 99.3% recycle rate over the last 4 years; lithiums are optimistically estimated to have a 30% recycle rate. Recycled lithium is about 5X more expensive than virgin lithium and is less desirable. (Any iron contamination from LiFePO plates is damaging to the other cobalt chemistries, so there is reluctance to use it.) The cobalt-based plates do have value but overall the economic and legal incentives for recycling lithium batteries are not there, so neither is the infrastructure. And half the world's production of cobalt comes from the DRC - not the best source. Because of its advantages I expect the recycling situation for lithium batteries to change - in the future. Today the OP needs to replace his batteries...

Greg