the Deka is an AGM battery where the odessey are gel based..
for a little reading:
AGM Pro's: better cycling and depth of dischager over the wet or gell batteries. While most wet batteries are supposed to only go to about 50% depth of discharge, the AGM's are able to go to about 20% depth of discharge without harming them PROVIDED that you don't overcharge them at too high a voltage on their return. What does this mean in numbers? If you have a Golf Cart battery that is 220 amp/hours for both the wet and the AGM, then the AGM would be able to have 176 ah. of useful capacity (220 X .80) vs. the wet battery at 110 amp/hours.
When comparing price for value's sake, if the GPL-4C costs $205.29 for 176 ah, that is a value of $1.16/ah. vs the wet battery at $69.20/110ah. with a value of $.623/ah. (54%). So why would a person buy an AGM? Read on.
AGM's need no watering and will receive a charge faster than wet batteries or Gell batteries. How much faster?
Concorde, our manufacturer of the Lifeline series, says over twice as fast. Throw Peukert's law out the window: the physical compression of the plates in the cell compartment, when coupled with the better quality of materials in an AGM give it far less internal resistance than the other types. Practically speaking this means less time to recharge your batteries while underway.
AGM's can be mounted in any position, require no room for venting and therefore can be installed in living quarter sections of your boat. This can be especially important if you already have a cramped space in mind for your batteries. Under the bunk, in the lazarette, under the molded seating area, or way up in the dark part of your boat are just fine for the AGM's. Also, because of the low internal resistance of the batteries, they were tested by the Coast Guard for their potential for explosion and they passed with flying colors (excuse the pun) by not exploding when heated to 200 degrees f., then dead shorted! So these are some amazing batteries.
AGM's also are virtually maintenance free: although everyone should visually check the terminals and general condition (for swelling, corrosion, black post, or high temperature) of a battery at least every six months, or before a big trip. The charts that Lifeline has also state that they have more life cycles than Gell Cell batteries (insert chart). Will they last longer than the wet lead acid batteries? Who knows: we have an old addage in the battery stores that states that "batteries don't die, their owners kill them."
AGM Con's: Price is pretty stiff when compared with the wet lead acid batteries--generally by 2 or 3 times. This difference begins to fade if any of the above items listed are important to you: cramped space, no maintenance, difficult mounting, rapid recharge, explosion-proof and non-gassing. But if you are from Missouri, the Show-Me state, and if you don't need any of the fancy features, and you are willing to slosh a little water or acid on your jeans from time to time, then the wet lead acid battery is a tough design to beat overall. As a value of Dollars per Amp/hour or Dollars per year life expectancy, the AGM takes a back seat to the wet lead acid battery if you don't need any bells and whistles.
Gell Cell (or gelled electrolyte where the acid is suspended in silica) Pro's: According to some of the folks who really need a higher number of shallow cycles, the gell cells do better. This contradicts the Lifeline chart but the folks who use the Kangaroo Kaddy and some wheel chair folks claim that the gell cells last for a longer period of time. At our stores, we have seen both AGM and Gell Cells poop out with too much cycling. I think that the jury is still out on this "Pro." This isn't much of a "Pro" is it?
Gell Cells were the first and some of the original Prevailer batteries from Sonnenschein are still out there. Exide has bought the brand and the technology from the Germans and is selling them today. We currently do not sell Gell Cells or any other gelled electrolyte batteries where the acid is suspended in silica. Read on for more Con's.
Gell Cell Con's: Price and a convincing argument that they hold up better and longer than the AGM batteries.
Although they were the first, they are not very popular at all any more. Perhaps this is yesterday's technology that has moved on.
Gell Cells do not do well in high heat locations (over 80 degrees f.) because of the voids that develop as the gelled acid hardens with cycling. As it hardens and dries, the capacity diminishes and the battery begins to swell as if ready to hatch. The voids that develop as the hardened acid pulls away from the plates is another reason for lost capacity. Eventually, the silica suspended acid pulls away from the plate and is no longer useful in the charging or discharging process.
