Originally Posted by micro_builder
i found this problem too. i'm guessing there's something in the way between the charging socket on the plane and the battery, probably a chip of some sort.
There's a diode in the battery line as a protection against wrong polarity, and the Tx loader circuit is adapted to this. A standard lipo loader will always see a battery voltage that is one diode voltage drop too big, so it's fooled into thinking the battery is already full.
You can remove that diode and put it into the Tx' charging cable, but then you have to do this mod to all your planes if you still want to use the Tx charger. Or you simply add a new connector directly to the battery line.