From the fellow's who travel around the country servicing UPS systems and the like. . .
AGM batteries will not have the life expectancy of a standard flooded battery. Jells are just too costly for what they provide. . . . unless you desire to mount them in unusual positions. I asked about the pulse chargers and he confirmed they can lengthen the life and doesn't see why . . .they have not caught on more as they have been around for a number of years. Oh and yea he can get me a deal
Richard,
I've never read that AGMs have less life expectency, and have read several sources that say they're about the same. Here are some resources with battery info.
AGMs ARE a lot more expensive, though. You might consider Wal-Mart's maintenance-free Everstart Marine/RV Deep Cycle/Trolling batteries. I don't know if they're available in Group 24 size, but I had one of their Group 27s powering my backup sump pump. It lasted about 7 years on the charger before it wouldn't hold a charge any more. It never had to be discharged very much though.
As far as battery life is concerned- keeping them charged will go a long way to preserving them. I have 2 flexible mat solar cells on top of the companionway slider that keep them topped off, plus shore power and a charger that work as well. Discharging batteries will shorten their life expectancy quite a bit. I think that is one of the most important things you can do to preseve battery life.
I too have read a lot about batteries so I went to the field . . . .
These fellows deal with all kinds of batteries and charging systems all day everyday and he sure had no reason . . that I can think of to aim me wrong . But who knows ???? I know when I only read about a many things . . .you'll get spin on them and if you go to a pro in the field. . . who BTW needs to have nothing to gain $$$ you ought to get the straight skinny. It appears I can buy AGMs from him for about the price I would pay for good/best quality flooded batteries . Gels for about the price of AGM's So I can there by get a pretty darn good price on top of the line FRESH flooded batteries ..He talked about that a lot ...
He said" its your money but if it was mine I wouldn't "
He said maintenance is the key to long life . Never !!! Bottom out a battery freeze run dry etc etc . we talked for about 20 minutes over coffee . . my treat If I where to just go out and buy he suggested Exide as a upper shelf battery
No, it was a very casual talk over coffee. I asked a few questions and if I had , had a list I could have done a much better job of it .
My biggest question really was about the AGM's . Were/are they worth the extra money?? I asked if I was stranded and just needed a new battery who should I choose and how to maintain them etc . It was not by any means a scientific discussion...Just two guys shooting the breeze . . ha tell me what you know about . . how about. . . . what if?. . . who's the best? . . . that kind of thing .
I'm not an expert but I've been working with AGMs and standard flooded electrolyte-type batteries for about twenty years in a variety of aeronautical and industrial applications. AGMs are excellent if you can achieve the following:
1. Filter the charging ripple to less than 4%.
2. Avoid depth of discharges to 1.91 volts/cell (11.46 volts total).
3. Avoid ambient temperatures greater than 77 degr. F.
4. Use temperature regulated float charging that is accurate to within 0.01 volt.
So, from a practical viewpoint in a boat where the above conditions are not always met, I would expect about a three year life expectancy for an AGM battery. I wish I could find a suitable sealed recombinant-type NiCad battery to try sometime. The old flooded-type stationary NiCads would typically last up to forty years.
I'm getting ready to replace my wet cells and have started reading up a bit on these choices.
From what I am understanding, life expectancy is not itself the determinant on which type to buy because the environment and usage pattern has so much to do with performance. In other words - it may well be that in some applications it is foolish to buy AGM's because they gain nothing, whereas in others AGM is the only way to fly.
The usage pattern on my boat: Sits for days at a time with shore power and a good charger, then has a period of heavy use over a weekend, then back to the charger. The way I like to use them on the weekend, and the fact that I have a Honda BF50 with realtively weak alternator, means that by the time I get home they are pretty deeply discharged. This type of cycle is deadly to a traditional wet-cell lead acid battery.
Additionally, as I move to replace these batteries, I am also planning to add an autopilot, which adds another fairly constant drain.
So, what I am looking for is: which type of battery is most tolerant of repeated deep discharges, fit in the space where my 2 batteries are now, and carry enough amp-hours to do what I need.
From what research I've done thus far, I think gel cells are fitting the bill. Overall, they may not last longer than a wet cell, so the final determining question is: "Will the added reliability be enough to justify the added cost?"
- AndyS
Note: Over this past winter I took my batteries out of the boat, charged them fully, and stored them in the garage - not on a maintainance charger - for about 6 months. In the spring, the charger topped them off very quickly, but I still think that leaving them without a maintainer charger was bad, and is probably why I am finding that my one-year-old wet cell batteries seem to have much less capacity this year than they had last year ... I almost had to try the pull-start method with my BF50 2 weeks ago...
Next time out, I'm going to go with the Trojan brand golf cart batteries. They are conventional acid style. They are a bit more expensive, but are designed for repeated deep cycle. For now, I'm using a couple big marine units by Costco, and an onboard Vectron (WalMart) smart charger. A fellow boater swears by the Trojan units....BTW, they seem to franchise their dealers...for example, only one or two places in Reno that carry them. Anyone else tried them? Jack
Moe wrote:Trojan T-105 golf cart batteries are VERY popular with RVers, as are similar sized Costco, etc ones.
. . . The second downside is that they're taller than the 12V versions, and won't fit in many RV battery compartments. Moe
Moe,
I thought golf cart batts were physically enormous, and, I've never noticed anything similar in Costco. Are you speaking of a footprint similar to G-27, just a little taller?
I'm thinking of just swapping to a pair of Wally's marine, dual-function (?) wetcells. After all, the factory starting batt plus a marine unit have lasted just fine for five years with only the Suzuki 60 for recharging.
