I would like to use 3DR Power Module with my APM 1.4. Which pins of the APM should be connected for Voltage and Current Sensor?
Which pins should I best use for powering the APM via the Power Module instead of BEC?
…have already killed a APM with wrong wiring…
The PM is really not designed to power the APM1.4 due to its unique APM2.5/6 power connector.
I would suggest that you continue to power the APM1.4 with a BEC and split the APM input/output bus power rails as shown here: http://diydrones.com/profiles/blogs/simple-apm-2560-power-hack
Then use an AttoPilot Voltage/Current senor as described here: http://copter.ardupilot.com/wiki/common-using-a-current-sensor/ You will have to get an APM1.4/Oilpan schematic to see where the Analog pins are on the Oilpan so you can measure the voltage and current signals coming from the AttoPilot module.