Anyone have any information on the new "Duracell" AGM 31 series batteries that Sam's Club sells? The price seems to low compared to other AGM batteries. Junk maybe?
Sam's sells them for $166.32. From what I can find out they are made in the USA at "East Penn"
They're the same as the East Penn Deka Intimidator 8A31DTM battery. List price on the Duracell branded battery is $250, and on the Deka branded battery is $350. $166 is an excellent price for that battery.
It's a "marine" hybrid, which is exactly the same as a "truck" battery. You'll see many batteries marketed as "truck" batteries, and the same identical battery but with different posts or a different color top will be marketed as a "marine" battery. For example, Optima yellow tops are truck batteries, and the blue tops are marine, yet they are the same identical battery in the same group size.
(I mention Optimas only because they are well known and widely available, but I don't recommend them at all. Exide is the other manufacturer offering spiral design AGMs, and they have the same inherent problems as the Optimas. Some people find they work just fine, but they have a horrible customer return rate due to an unacceptable failure rate of more than ten percent. The spiral design of the cells dictates they can at the most be 73% as large as a more common rectangular or cubical design, and is more prone to failure. So it's most definitely less bang for the buck.)
Hybrid batteries give you the best of both worlds, to a degree. It's best to use a battery designed for cranking as the cranking battery, and a battery designed for deep cycle operations for deep cycle, as each will out perform hybrids. A hybrid won't perform cranking operations as well as a cranking battery will, but it'll be close. Nor will it perform as well as a deep cycle battery, but it'll be close for modest deep cycle operations (lower amp draws especially). If your amps draws are 5 amps or less, a hybrid will perform quite well. These batteries have enough plate surface area to crank your engine quickly, with battery plates tough enough to withstand moderate deep cycling.
Marine AGM batteries are specially designed for engine starting and the long deep discharges typical of marine applications, with "long deep discharges of typical marine applications" meaning a trolling motor and a few lights, not a microwave and a refrigerator and a rice cooker and a crock pot and a TV.
As with all AGM batteries, with reasonable care (not routinely discharging them too much below 50% Depth of Discharge, and properly charging them) the Duracell / Deka should well outlast the warranty by several years.