My cousin recently purchased an Optima marine battery from Bass pro shops hoping to get more run time out of a nice battery than we get from the old ones the local lake has. He purchased the biggest model I think the D31M but we've been pretty let down by it, It only lasts a little more than the other batteries if not less! We've been charging it on maintenance free on 2A and the charger has a gauge to tell when its fully charged. Did we just get bad battery or is there something we are failing to do or possibly didnt do? And we are not in a boat but a Jon.

never used optima ,i have aways liked the interstate marine batteries.

Why in the name of God are you charging at 2 amps?  :-?

The D31M battery is only 75 ah capacity. That is the same capacity of a group 24 conventional deep cycle battery. Most fishermen use at least a group 27 deep cycle with around 100 ah capacity.

Charging at the 2 amp setting is going to take at least 5 to 7 days to charge it.  Give it a real charge and try again.