This is interesting:
AGM batteries are becoming more and more popular. They excel because most are better equipped to handle shock and vibration, and will typically give you several years of maintenance free service. Unfortunately, most AGM batteries vent at 1-2 PSI causing them to corrode surrounding electronics similar to the Gel batteries. Almost all AGM’s today use recycled lead shortening their service life. They are typically more sensitive to charging than a flooded batteries, however they are less sensitive than a gel. There are many AGM’s on the market but don’t just go out and buy an AGM battery and think you have the best. You may have been better off saving that additional money you just spent and bought that 100 year old technology found in a new flooded battery.
The Odyssey Battery however is an AGM battery that is very unique and technologically advanced. It was designed to meet the demanding needs of the US Military with respect to heat, cold, shock and vibration, and to last much longer than other batteries. It is currently used in tanks, fighter jets, battle ships, and many other military applications. On top of this it delivers higher cranking power while also being the best deep cycle battery available (two to three times the cranking amperage of other similar sized batteries and the ability to be drawn down to 100% over 400 times). Other attributes include the ability to sit dormant for up to two years and still hold enough charge to start the motor it was intended for. This is very important because we often don’t get to use our boats as much as we would like during the season. The Odyssey battery actually lasts up to 6-10 years which is attributed to it being manufactured with 99.9% pure virgin lead. The US Coast Guard has 500 batteries in 50 Bollinger 87 foot protector class cutters since 1998 without a single failure to date. On top of all this, it is maintenance free and will not vent during normal operation due to its patented technology to reuse its internal gasses. It is also the only battery to claim an explosion proof design.