RE: Hitec Eclipse 7 battery life
Nicad cells sometimes suffer from a phenomenon known as voltage depression (VD) -- sometimes erroneously referred to as "memory".
What happens is that, after a number of partial discharges and full recharges, the batteries begin to operate with a reduced output voltage early-on in their discharge curve.
The result is that, when used in any "smart appliance" that monitors battery voltage (like your transmitter), they appear to be going flat when they actually still have a goodly amount of charge left in them.
A full discharge (down to 1.1 volts per cell -- 8.8v for a 9.6v pack) and recharge will reverse this VD effect and restore the higher operating voltage.
Make sure you don't discharge your battery to less than 8.8v however, or your risk reverse-polarizing some cells which can damage them.
If you're using Nicads, a battery cycler is not a bad investment -- especially if your flying habbits tend to result in only a very light discharge between recharges.