New Batteries

[nautiguy]

We're about to replace the batteries. We now have 2 group 27 wet cell house and one group 27 starting batteries, and am thinking of replacing them with AGMs, possibly Optima spiral wound.
Does anybody have experience with these? Should II plan on replacing the engine alternator?

Norm

[Peter Malcolm Jardine]

Okay... my .02. I think for most people that AGM and gel's are not terribly necessary. Both of them will withstand vibration better, so for offshore racers, that's all they use. They also do a overall better job of withstanding repeated discharges in excess of 30%. That said, it's still cheaper to get a bigger lead acid, say a group 31, and get more overall capacity. In a sailboat, I would build epoxy coated plywood battery boxes, with lids. I think it's better to build capacity than hi tech smaller batteries. You shouldn't have to replace your alternator with only two batteries aboard, but I don't know how big your present one is. You also haven't mentioned your cruising style... if you are out for days at a time, have electric refrigeration, inverters, etc, this all affects how much battery you need, and how your charging system is set up.

[nautiguy]

Thanks.
We are beginning to fit out for some long distance cruising, eventually through the Panama canal, through the Caribbean, and up the East coast. What interests me about AGMs is the reduced maintenance requirements. The two house batteries are in a box as you describe but are hard to get to. Because of this i don't check them as often as I should.

[willmarsh3]

I don't like gel cells because they cannot tolerate charging voltages above about 14.4 volts for any length of time. It causes the battery to swell up and leak acid anyway. After that the battery accepts only a small fraction of its previous capacity. The battery is ruined so it then has to be replaced. It was the most aggravating and expensive issue of my "Big Cruise" in 2001. I use alternator and solar charging. It only takes one to fail and put out too much voltage. I know this from first hand experience. That's why I switched to wet cells.
Just to clarify over voltage charging of a wet cell will cause the electrolyte to bubble so it should be avoided. The bubbles are hydrogen and oxygen created from the water in the electrolyte. But if I see an over voltage situation I can fix it, then top off the batteries and they are not really any worse off.

As for AGMs I have heard both ways on whether or not they tolerate over voltage charging.

[Nordicthug]

We're about to replace the batteries. We now have 2 group 27 wet cell house and one group 27 starting batteries, and am thinking of replacing them with AGMs, possibly Optima spiral wound.
Does anybody have experience with these? Should II plan on replacing the engine alternator?

Norm

http://www.phrannie.org/sources.html

Here's a website with an extensive section on batteries, chargers, power sources adaptable to DC systems. More information than anyone can imagine. You should find answers there to questions you don't yet know you have.

Gerry N.

[willmarsh3]

Excellent website, Nordicthug.

I don't mean to condemn gel cells out right but in my experience and judgment there's no way to guarantee the careful charging that they require on a sailboat. Not at any reasonable cost, anyway.

[kc8pql]

I use 6 volt golf cart batteries, wired series/parallel, for my 440 ah house bank. They're by far the best bang for the buck in AH delivered over their lifespan. I've never found toping the water up now and then to be that much trouble.

[Frank Wentzel]

KC is right. Golf cart batteries are made for deep discharge and provide the very best dollar vs watt hour ratio. They are also almost universally available. I have been in the battery industry since 1969 (design and chemistry) and, until lithium ion batteries become a commodity item, I believe you will do best with golf-cart batteries.

/// Frank ///

[nautiguy]

Hm, I hadn't thought about 6 volt batteries. They would work. I'll have to see if they will be any easier to check and fill then the group 27s that are in the space now.

I agree with all of the comments about gel cells, which is why I'm leaning toward AGM batteries. Although they are more expensive, they are more forgiving on the charging question and can actually be laid on their sides.

I am wondering if anybody has experience with the spiral wound type such as the Optima batteries. Supposedly they offer an advantage in charging rate and because of the sprial winding of the mat they won't calcify as quickly.

[willmarsh3]

I had looked at getting AGM. They take a charge faster. That could be a problem because of the bigger load on the alternator. If one gets a larger alternator then that means more side load on the engine bearings in a typical alternator setup. This means that the bearings wear out faster which is an expensive repair. I'm in favor of the golf cart batteries too since they were designed from the ground up for high current deep discharge as in a golf cart.

[Peter Eikenberry]

Here's something you should read before you select AGM or Gel, or stick with wet cells. All have their advantages and disadvantages. http://newboatbuilders.com/docs/BatteriesandChargers.pdf Yes golf cart batteries are true deep cycle batteries but so are D8 wet cell 12V batteries. Most of the Marine deep cycle batteries are not true deep cycle. They are a combo with both thin and thick plates so they can be used for both deep discharge and starting.

Wet cells aren't that difficult to maintain. I have a converter charger that keeps them up to snuff and I check the electrolyte level once a month. I also have a battery monitor that gives me a pretty good indication of their charge state. So if you have a good charging system and a monitor you really don't need to check them all that often. Once a month is fine. Plus, if kept charged they should last 4 to 5 years. I use regular group 24 deep cycle wet cells by Interstate and they are about 3 years old and still just fine.

[C. Ross]

Anyone have experience with Trojan L16 floor machine-type 6V batteries, or Caterpillar batteries? I'm looking for some big house deep cycle capacity.

[George Ray]

I use (4) L-16 and (2) 24-series that i can move easily. The L-16's are great if you have a place for them and a cargo boom to move them.

[Tylerdurden]

I use 6 volt golf cart batteries, wired series/parallel, for my 440 ah house bank. They're by far the best bang for the buck in AH delivered over their lifespan. I've never found toping the water up now and then to be that much trouble.

I still haven't found anything else with the same bang for the buck.
I run the same and have for years.
I run a group 31 for starting in most instances. Same issue, bang for the buck.

[Paul Fitzgerald]

I have had a couple of 12V AGM's collapse a cell in sailboat applications. I suspect they are all not as tough as they make out.
Currently I'm using top of the line AGM's to see how they hold out. Their advantage is deeper discharge rates than conventional batteries, so you effectively get twice as much storage as a conventional battery. They also self discharge less, so they stay in charge longer if they are not topped up.
I'm going back to trojans if these fail.

[C. Ross]

I use (4) L-16 and (2) ... a cargo boom to move them.

At 124 lbs each L16s ain't light. Four L16s and two 24's? That's a lot of house bank...

[Frank Wentzel]

While much of the information in the link from Peter is valid, the guy is NOT a battery person, so be wary - he must be copying from other sources without fully understanding what he is copying. He states several times that lead acid batteries contain lead, zinc and sulfuric acid. There is no lead acid battery that has ever had a zinc plate. Zinc has never even been used in the lead alloys that are used to cast the zinc grids. Other than minor alloying materials in the grids that are used to make the lead grids stronger and more castable the only metal in a lead acid battery is lead. Both plates are composed of lead either cast or “expanded” into a grid or screen with tabs for interconnection. The active material on the positive plate is lead dioxide (PbSO4) and the negative active material is sponge lead. All interconnections are also made of lead. That is why the lead acid battery has the highest recycling rate of any recyclable commodity. It is all either lead, plastic (which becomes fuel in the recovery/smelting process) or glass separator material (which becomes part of the smelting-flux).

/// Frank ///

[LeeG]

Frank, do you know anything about Firefly batteries ? I think they're supposed to be in production by the end of this year or so.



http://www.fireflyenergy.com/index.php?option=com_content&task=view&id=204&Itemid=89

[Tom Lathrop]

Nigel Calder has an article about new battery technology in the latest issue of PBB that arrived today. Some that will take a charge many times faster than previous ones. Some are available now.

[C. Ross]

LeeG-I've also been watching Firefly with interest.

Their product is being positioned as cold cranking plus house bank. I'm about to invest in separation of cranking and house, so would be interested in knowing whether Firefly is the real deal.

Frank?

[LeeG]

C.Ross, I was expecting the stats on the battery to have a higher amp/hr rating or a lighter battery. It looks to be another type of AGM, is that right?

[Lew Barrett]

Cris,
Seperating start and house will provide you with a great deal of peace of mind. Good move if you stay out for any length of time.

[C. Ross]

Lew-
It's good advice. This spring's projects include separate battery banks and inverter.

LeeG
I know very little about batteries. I know that Firefly's big thing is that they use a composite foam with lead oxide embedded in it, rather than lead plates. Supposedly that allows a battery than can take deep cycle discharges and also produce high power/cold cranking, at lower weight and cost. So to my earlier point, if they really were delivering a battery with a very different profile, maybe separate cranking and house banks would be less crucial. Pretty clear this technology is not going to hit the market in time to help me, but it's interesting nonetheless.

If you compare Firefly's Oasis battery to something like a Trojan 31-AGM, both have about 100Ah at a 10 hour rate. Firefly weighs 71 pounds to Trojan's 74. The battery size is the same. Firefly's cold cranking amps is 650, Trojan's is 720. Firefly's reserve capacity is 215 minutes at 25 amps, Trojan's is 190 minutes at 25 amps. So far nothing really different, I think? Difference if any must be lifespan, how deeply the battery can be discharged, something else?

Is there a battery expert in the house?

Cris

[Frank Wentzel]

I wonder about Firefly as well. There have been many attempts to utilize alternative materials for the battery grid, including: aluminum, stainless steel, titanium, coated fiberglass and graphite. Those are the ones I know of, I'm sure there were others. None of them made it in the marketplace - most didn't make it out of the lab. I think I'll wait to see what happens when they are actually introduced. I have seen a number of products that didn't survive their own hype.

I'm working in lithium batteries now. That is, I am qualifying Chinese made batteries. Nobody in this country is making large format lithiums that you can actually obtain - they only give out press releases and tell you that they are working with unspecified OEMs. I don't know how long affordable lithiums will take to get to the market but they will take over when they do. We are talking 2000 plus cycles at 1/3 the weight and size of equivalent amp-hour rating lead acid batteries and no derating for 1-hour rate discharge. There is no gassing and, if the chemistry is the correct type, no fear of catastrophic failure. The only problem is an OEM cost of $240 for a 50AH, 12V battery FOB China.

/// Frank ///