Watt Meter Interesting Results

[mlachow]

I was checking the current draw on my new GPS Light model with an inline watt meter. It was just the fuselage with the RX, two servos, as well as the Sparrow GPS and telemetry module. When the motor was off, I was expecting 100 to 200 ma current draw, but I would see 700, sometimes up to 2 amps. The model is a P2K V-tail GPS version and that fuselage really has the radio gear and servos shoved into very minimal space. I was thinking I had some kind of damage to some wires or something like that. Or maybe the GPS unit.

Nothing appeared to be wrong and at times, things were perfectly normal. It turned out to be RF interference with the watt meter. I had both the Transmitter as well as the GPS Transmitter and both were pretty close to the meter. If I shoved the TX antenna close to the meter I could see it change. Eventually I stuck a conventional servo meter in the lead from the ESC/BEC to the RX and I had a nice current reading. It never changed. But the meter from the battery to the ESC would jump around if you got the RF close enough to the meter.

[lenb]

Ya see, my move would have been to install larger batteries!! Interesting though.

[mlachow]

The numbers didn't add up. My perfection with similar equipment would have crashed long ago if those were real numbers. And if you look at a P2k fuselage. There is very little spare room.