I too use duracell 2650's and found them to be great cells.. what charger are you using??
Again, most of my comments are a limited to the 24 batteries I've played with.
My comments about duracell 2600s were from a "one time" occurrence after a quick charging. They actually worked fairly well after a trickle charge.
But the latest "quirk" discovered in testing the 4 duracells is the uneven discharge rate. Two of the cells continue to act as if they are some how less chargeable, and therefor discharge to a greater extent when mated the other pair.
My only guess is that I damaged two of the batteries - or somehow the chargers do not charge both pair evenly......
I did discover that an unloaded cell can still report 1.15 volts but not be on average = strong enough to run my Stella "double eh"--- blinks outs almost immediately.......
And like I said, I have no experience, so far all my batteries have less than 5 cycles of usage.... my own concern is to be carrying the right amount for any given overnight ride.....