Taken from a website...
The Odyssey Battery 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.
Charging the Odyssey battery is similar to a flooded battery. It is not sensitive to charging like other AGM’s and the Gel batteries. In fact, the Odyssey battery has no restrictions on the inrush of current and will recharge in one third the time of a conventional battery. This allows the battery to be utilized with traditional flooded chargers and typically does not require replacing your current charger in many applications. Most marine three stage chargers available today work very well for charging the AGM batteries.