New Batteries Needed

[hellosailor]

Since you've already got matched dual-purpose batteries, and your charging systems are set up to treat them as one battery (rather than separately monitoring and charging each), I would suggest your best bet is to use the batteries in the way that matches your charging system.
Keep them on "both" all the time, for starting and charging use. When you are going to be anchoring out, etc. and need to make sure you have one battery available for starting (even if you fall asleep with all the power on<G>) then you switch to one battery only. If you don't take that battery down too far, you can start from it solo, and recharge it solo. Next time out, use the other battery.
Simple enough?
If you take it down too far to start, then you'll have to start off the other battery and--unless your battery switch allows you to safely switch while running--you'll have to go home that way. Some battery switches allow you to switch while running, most don't. If you have the "most don't" kind and you switch while running, you can blow the alternator/regulator out. Not a good thing. (Personally? I'd suggest making sure you have the better switch, replacing it if needed.)
If you have the better switch, you can start from the one, then switch to both, or switch back to the "used" battery only, in order to make sure IT gets the full charge first.

Once you cross out the parts you don't have or aren't interested in, I'm hoping that will boil down to something simple for you.<G> Most charging systems can be upgraded and optimized without too much trouble, if you want to get around to it. But for a lot of folks, it is simpler to replace the batteries every few years instead. One of the many personal freedoms in sailing.<G>

[RandyAbernethy]

It is a lot easier and cheaper to replace a battery at the ship’s store than to find yourself in the middle of nowhere on "All" with two dead ones. When the motor is not running I suggest you switch to the house battery.

Many alternators on boats these days put out no more than 14.2 volts in order to safely charge most wet and most Gel/AGM batteries. As Rick mentioned, every battery is different and so is every alternator. Some alternators put out 14.4 volts to optimally charge wet cell starter batteries and some AGMs will cook at this voltage. Make sure that the peak output voltage on your alternator does not exceed the max charging voltage on your AGMs. If you over charge your AGMs they will die quickly.

If your alternator puts out safe voltage for your AGMs and the AC charger you have is 3 step and set for AGM, having this charger and your alternator set to charge “both” is a pretty solid and fool proof setup. Not perfect, but perfect is not available anywhere on this planet and especially not in boating.

Unless you’re ready to tackle the alternator optimization issue many other efforts to optimize charging patterns may be for naught. You can get a fancy alternator with an external regulator but it might be overkill for your application. By the time you depreciate the work and capital involved you probably could easily justify taking a chunk of life out of your batteries due to suboptimal alternator charging now and again. Most people who go for the high zoot alternator setup leave the stock alternator in place to charge the starter battery (which is probably what it is optimal for) and add a second higher output alternator to charge the house bank. These folks tend to have 400+ AH for the house.

It is worth it to get an AC charger that has a three step charging regime and support for AGM batteries. For more money you can buy a charger that has temperature compensation and dual independent outputs so that each battery bank (starter and house) can be charged optimally. Again, you have to justify the expense, which may be difficult if the AC charger is not the weak link.

If you have quality AGM batteries they should provide hassle free service for several years even with a less than perfect charging setup.

[sjs]

I really appreciate the helpful info guys. My boat was launched yesterday and I will be going down to it today. With all this education at hand I will be monitoring and logging the battery and charger meters carefully to see how it goes. Thanks.

[hellosailor]

Rick-
"Do you believe everything that marketing people put on data sheets?" What, in a capitalist free market state, anyone would lie?! To me?!<G> Absent the test lab, I have to go by what seems to be published by the least disreputable sources. I'm quite happy to get better information from you--but why didn't you tell me all that years ago?!<G>
Brand names ar still important, you make a good point. For the consumer there's still that problem of who and how do you believe to make the decision though. GNB batteries? They claim to be a division of Exide, not the parent company. Exide is a big name, but I haven't been aware of Exide AGMs in the past five years, the way Optima has been marketed to the general public. I know they make them under the "Orbital" name now--which seems directly targeted at Optima's "round" message. I didn't know they owned the Sonnenschein® brand (or the US rights to it anyway) and last time I went looking for AGM batteries...finding anyone besides Optima (or the high end market) took days. But it has gotten much easier than it was....um, about four years ago, last time I went looking for them.
Still, it seems like you also favor AGM in general? As I do.

[Rick]

Yeah, I guess that I do prefer the AGM in general. I am still using a 4D case size Prevailer gel that I hammered for years in the lab and then put it on my boat it is over 10 years old now. I have other AGMs on board as well, each one has a monitor and I can see how they track each other operated in parallel. The old Prevailer tracks fine yet demonstrates aging parameters like increased internal resistance and some permanent loss of capacity.

One of my AGMs is actually a Chineese brand that tested out to 205A-hrs (and wonderful energy capacity) in a 4D case. I've never seen any other battery test out that high in a 4D case. Heck, once I tested a flooded-cell battery in a raised 8D case (much taller than normal). It was a huge heavy brute that tested out to only 150A-hr which really dissappointed the manufacturer who thought it would reach 250A-hr.

[hellosailor]

Rick-
The folks at AmplePower still recommend gel, uniquely enough. They say that in the long term (10+ years) it holds up better than anything including AGM, and that they've had reports of 20-year old gels still in good service.
Dunno. The more you ask...the more a plain sailboat with NO electronics sounds better all the time! Of course, once you let a Walkman in the door, you know, the camel's nose in the tent?<G>

[Rick]

Yeah, I understand the attraction of back-to-nature and the desire to be free from technology. The Pardeys have proposed this for years yet a realistic evaluation of the people who they appeal to are, by-and-large, not physically or mentally or experientially equipped to deal with their lifestyle even though such people might THINK that they are.

After living on board two different cruising sailboats I have come to love the conviencies of home aboard. In addition, I cannot keep a lady long aboard if she wants to go to a house or a hotel in order to satisfy a comfort need. Therefore, I do everything to provide that with the best quality and reliability that I am able.

The challenge is to draw a line regarding boat size that one can realistically afford to buy, outfit, and maintain while accommodating the comforts of home. One just cannot do that without the technology, like it or not. Here is where fantasy MUST meet reality else suffer the consequences of dissatisfaction. I'd rather rebuild a head than mow the lawn, and I've done a lot of both over the years. I'd rather plan out and fuss over just how to accomplish the design and installation of a comfort feature which has a high reliability factor than worry about whether or not something marginal is going to hold up.

One time in large seas and high wind we hove-to, took a hot shower, and went to bed for a few hours of rest dry and comfortable. Couldn't have done it without the technology, thank-you-very-much! Another time near Panama other cruisers came to ask for me to communicate on the SSB because their installations were sub-standard at being able to communicate under difficult communication conditions...they just did not take the time to investigate better ways of ensuring good communications. The list is only as endless as the choice of devices and systems aboard that one would like to be dependent upon for physical and mental well-being. Let the Pardeys drop anchor for 6 additional hours or more because they refuse to purchase a motor of any kind to take them to immediate safety against wind and current. Not me, again thank-you-very-much.

[BC Mike]

Rick, my thoughts exactly.
I chuckle at the adds that read 26 foot boat sleeps six.
With all the junk I have on my large 28 foot boat there is barely room for two. Love the fridge cause it keeps my beer cool. Love the 15 hp Yanmar cause it gets me where I want to go. Love the sail invertory cause I have an option for all the winds.
Michael

[sjs]

Darn Rick, that strikes me as profound. I fall in the simplicity camp and I think I am going to think some more about my camp because you make sense. Still, . . . .

[hellosailor]

"I chuckle at the adds that read 26 foot boat sleeps six."
But gee...we've done six on a J/24.<VBG>

[speedoo]

Trojan group 27 AGM did very well. See their home page, and click on the link about the article for a pdf of the article.

http://www.trojan-battery.com/

I seem to recall seeing somewhere some very negative comments about the way Practical Sailor evaluates batteries, but this article describes a test that appears to be pretty well done.

At $169 apiece, these Trojan AGM's appear to be a great solution for a lot of sailors. When did Trojan start building AGM batteries? Anyone know?

Also, it appears to me Trojan has significantly expanded their entire product line. Check out all the 6V battery sizes they now offer.

[CaptainK]

Maybe someone from Pratical Sailor magazine is being paid off, to make the bad evalutions?

It's happened before with other magazines!!

[hellosailor]

Speedo-
Don't overlook the Group31 batteries, Trojan also makes them in AGM. Group31 often give you a nice bit of extra power at a lower "per amphour" price, and they are still small enough to move solo.

In the past 2-3 years a lot of companies have been motivated to build AGMs, apparently there are transportation requirements or preferences now to end the use of wet acid batteries on trucks and busses due to the acid spills in accidents. The same thing is supposed to push wet lead out of cars, emergency responders and accident victims being harmed by acid spills. All it takes is one jury trial and one finding that "your product was unsafe, it spilled caustic acid, pay the million dollars" and the entire industry gets motivated to change.

[CaptainK]

Acid spills.

Well that answers one of my many questions about why the switch over, from wet cell to the AGM's?

[speedoo]

hellosailor, yes, I saw the group 31's and I may very well go with them when I get to the point in my refit that it's time to put in the new batteries. I would assume they are not too expensive and that they perform even better than the 27's. Plus they are still manageable weight wise.

I was planning to go with the Trojan 6V wet cells, but I am delighted to see they are now selling AGM's.