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ContinuousWave: Small Boat Electrical
Dry cell batteries
|Author||Topic: Dry cell batteries|
posted 12-21-2002 11:22 AM ET (US)
The boat manufacturer I used to work for installed dry cell batteries as an upgrade/option. Although they're substantially more expensive, the dry cells became very popular for a number of reasons: They are smaller, very durable, and they can be mounted horizontally - which makes terminal access easier in many in-console applications; it also makes it easy to mount the batteries on a bulkhead "above the flood plain" so the batteries and wiring can be run in areas less subject to flooding. The dry cell batteries also tolerate long periods of sitting, deep-discharge abuse, and extrordinary vibration. If memory serves, they also have a much longer life-expectancy - which helps justify the purchase price. If I had space and weight constraints in a small boat I would use twin Odyssey dry cells...my .02
posted 12-21-2002 12:54 PM ET (US)
Optima is another brand that will work as you stated. They are a gel cell.
posted 12-21-2002 03:36 PM ET (US)
Duck twin, do the gel cells respond as well to charge-deep-discharge cycles? Are they similar size and weight? I've had the dry cells in two boats and they were wonderful in every respect but price. I'm feeling poor right now, and there's a lot I still need to do to finish my boat, so went with the ol'standard batts...and now I'm regretting it because of the space they take up. In a couple years I'll be looking at gel/dry alternatives. BTW, what's the origin of "Ducktwin"? Our state university mascot is a duck...and my wife and kids are twins... My wife is a duck-twin too...
posted 12-21-2002 05:05 PM ET (US)
Consumer Reports (www.consumerreports.org) has an auto battery test online (starting batteries, not deep cycle). They tested a pile of batteries for output and for life (charge, discharge, recharge, over and over). In its class the optima was rated 2nd overall out of 11 batteries in that class. It did excellent in the life test and above average for CCA and reserve. It also cost more than any other battery in the group ($140 for the 750CCA model).
Interesting side note; of the 5 classes of batteries tested, 1st place in 4 of the 5 went to a DieHard brand battery.
Interesting side note 2; the same company that makes DieHard also makes several other brands in the test. Those batteries did not test as well as the DieHard models on average. So much for saying "well it was made by company x so it must be as good as a brand x item".
Anyway, the article is a very good read.
posted 12-21-2002 10:10 PM ET (US)
Warrior, I went to the Consumer Reports page and used their search engine to look for battery ratings...but I didn't get to see the test results because I'm not a member. (I didn't bother with seeing what I had to pay to join.) I also put Odyssey in their search engine and got no hits. I'm thinking that it's possible they haven't tested the Odyssey batteries - but that seems unlikely given their success. Were they tested against the others in the reports you saw? BTW, I've got FOUR new Die Hards in my boat (two with switch on each engine); I guess I made the right band choice by accident...
posted 12-22-2002 05:06 PM ET (US)
I looked at the ratings page and I did not see the odyssey battery listed. I see Diehard, Napa, Exide, Interstate, Motorcraft, ACDelco, Champion, Kirkland (costco), Duralast, Optima and Everstart listed. They're all car starting batteries, but it gives you a neat look at which brands tend to do better than other brands on a brand by brand basis.
Subscription is $4.95/mo or $24/yr. If you get the magazine then it's only $19/yr for the online subscription
posted 12-23-2002 10:59 AM ET (US)
I'm certain the "dry cell" batteries you describe are not really dry cell...they are most likely Absorbed Glass Mat (AGM) type batteries. I have used four AGM batteries on my Mako 17 for the past 5 years (2 for the boat & 2 for my bow mount trolling motor). I agree with you, they are great batteries...longer life, quicker recharge, maintenance free, lighter weight, & they work at almost any angle. They are much more tolerant of complete draining & recharge than conventional batteries. They are supposed to last 3 times as long as conventional batteries...I'll see if that's true, but all four are still operating perfectly after 5 years for me.
They are similar in design to wet cell batteries, but the water in the battery is held in glass matts inside the battery. They are less sensitive to charging conditions than gel cell batteries, and are a better investment than gel cells in my opinion.
Mine are "Trolling Thunder" brand, these were aimed at the bass boat market, but the parent company has stopped marketing to the marine market (although they still make the same AGM baqtteries for industrial uses). But there are several brands of AGM batteries available now, including Optima and Lifeline. They are expensive, but I feel they're worth it.
posted 12-23-2002 11:15 AM ET (US)
My experience with "gel cells" has been with primarily emergency vehicles (police, fire).
These vehicles, when working a scene, typically draw much more power than the alternators can provide. Thus the batteries are given a thorough work out. They are discharged to near flat and recharged continuously. No lead/acid battery has held up as well as the Optima.
As I mentioned, the gel cell batteries also give them some mounting alternatives.
By the way, I responded to your "ducktwin" question via e-mail.
posted 12-23-2002 01:21 PM ET (US)
ducktwin, just for clarification, the Optima marine batteries I am familiar with are AGM, not gel-cell. These are two different battery technologies that have similarities in terms of being maintenance free & handling deep discharge, but AGM & gel cell batteries are different from each other. To my knowledge Optima does not make a gel cell battery.
The West Marine catalog has an "advisor" page on the differences & similarities between wet cell, AGM, & Gel Cell battery technology...it's a good read if you have the cartalog or find it online.
posted 12-23-2002 01:26 PM ET (US)
I believe you are correct. The "slang" "gel cell" what is used in the industry I speak of. It is probably not technically correct.
Thanks for the clarification.
Regardless, they offer mounting alternatives and can withstand repeated discharge/charge. They also withstand heat (the real battery killer) better than anything I've seen.
posted 12-23-2002 08:50 PM ET (US)
The Optima line is available at Costco. Bought a "red top" for about $105.
posted 12-23-2002 09:00 PM ET (US)
John W, you may well be right. I used the phrase "Dry Cell" because that's how they're marketed by Odyssey. Whatever they are, I found their performance remarkable - and much superior to traditional deep cycle batteries. I'm surprised more peope don't use them for marine applications. (I'd have them in my boat but I'm running short on money for my restoration project.) The Odyssey factory web page contains interesting performance data. I have included it here for the curious: http://www.odysseyfactory.com/
posted 12-23-2002 10:42 PM ET (US)
Here is a link to West Marine's Battery Chemistry page:
I've got two Optima D34Ms. These are the blue top, deep cycle, marine version.
I've read that some of the benefits of the Optimas include:
Optima's site is http://www.optimabatteries.com/
They ought to be better since they cost 2 to 3 times as much. The best deal I've found on the Optimas on the Internet is at www.batterymart.com . Although www.batteryweb.com and www.1st-optima-batteries.com also have them.
posted 12-24-2002 01:17 AM ET (US)
Interesting to hear how well Die Hards were rated. I've used them in my various boats and Jeeps for years with great results, after being let down by cheaper batteries in the past. I dont' even bother looking at anything else. They have always outlived their rated life for me, often by several years.
posted 12-24-2002 09:52 AM ET (US)
It is clear from the Odyssey website that while they choose to promote the term "drycell" to describe their batteries, the technology involved is that which is more generally known as "glass mat" or "AGM".
I have been very happy with the Lifeline AGM baatery I've had in My Outrage 22 for the past couple of seasons. I had a group 27 gel cell battery I was using in a single-battery application, but I wanted to go to a two-battery system, one cranking battery and one deep cycle battery, and my plan called for group-24 batteries mounted beside each other in desert-sand BW OEM boxes on the starboard deck of my splashwell.
My research led me to conclude that I wanted a typical lead-acid high CCA automotive battery for cranking, so I picked up something from Autozone with somewhere close to 1000 CCA and a good replacement warranty.
My second, deep-cycle battery took a little more consideration. Gel-cell batteries can be permanently damaged if they are inadvertantly overcharged, so they require more specifically designed land-based charging equipment that will sense the state of charge and go to a very light trickle charge or shut down when the battery reaches certain levels of charge. Additionally I came to understand that the technology in the charging system of my 1992 Evinrude 225 was such that with two batteries present one of which was gell and one of which was not, under some conditions the motor's charger couldn't tell when the gell battery was charged and would continue trying to work until it burned itself up, unless an isolator was added to the system. The wiring scheme and space available in general to accomodate a battery switch *and* an isolator in my open center-console boat left me not wanting to go that route.
Research into the AGM batteries showed that *both* of those concerns would be alleviated with the use of an AGM. The AGM was not sensitive to overcharge like gell cells were, and the charging system on my motor would sense the AGM was just another lead-acid battery, and would not be confused as to when the battery was charged; no need for an isolator.
I couldn't be happier with the results I've gotten from the Lifeline AGM, and would recommend the technology to anyone who feels they can afford the up-charge from a typical lead-acid application for a deep-cycle battery. The day may come when I'll replace my lead-acid cranking battery with another duplcate AGM; I'd lose a little in the CCA category, but not much.
posted 12-24-2002 10:09 AM ET (US)
The West Advisor on battery types is at
Die Hard has AGM batteries for motorcyles.
When you add the acid to AGM batteries, you
posted 12-24-2002 10:20 AM ET (US)
Kingfish, that was very helpful analysis. And you and John W were right. I spent quite a while on the Odyssey web site after I posted it here. The ADM-type battery seems like a good solution for the guy who wants to keep a back-up charge stowed somewhere on board.
posted 07-25-2005 12:37 PM ET (US)
my friend has a 12v dry cell battery on his boat, can we charge this up with a 'normal' car battery charger or do we need a special one? it's a sailing boat with no self means of charging
posted 07-25-2005 01:47 PM ET (US)
When you say dry cell, to you mean a gel cell, or AGM type battery? You need to know for sure, every type has different charge specs. The best thing to do is contact the battery manufacturer, or check their website, to get their recommendations. Better chargers have settings for each of the different types. You can get a charger from WalMart for around $50 that will do Wet Cells, Deep Cycle, and AGM/Gell types that has three different charge rates too. BillS
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