ORIGINAL: rctom
It's my guess that it's a combination of a charger with too-strict rules and batteries with too-high internal resistance.
Your approach of using a wall wart is good, but they are 50ma, not 500ma, and charging yor 2700mah pack from zero would take at least 4 days.
I suggest you look for a different pack with low internal resistance, the kind designed for electric motors. I'll bet that the plane will fly better also, I doubt you are getting full power to the servos as it is now.
TF
I have only had one flight on the pack and that was to see about how much would be used per flight.
I did a first charge as per Dave Thacker at Radical RC and then flew the plane after some radio set up time and used about 500mah
I then discharged the pack and first tried tried 2700 with the Triton and it kicked at about 625mah and the second time tried at 500 and it kicked again at about 275. I then tried the Activator and it kicked at around 325.
I checked back with Radical RC about using a WallWart that I had at the house from some old something that no longer works, but the transformer still does. It is a 9v 500mah wart that they said will work fine and it will then take about 6hrs. I will have to start doing a routine of Friday & Sat nites that I dis on the Triton and charge on the wart. Gone are the days of only charging at the field.