I've got an R/C vehicle used in various stage demonstrations. Two motors (left and right) with tractor steering. The motors are gearmotors that pull less than an amp nominal and are rated at 25 amps stall. No caps on motor terminals.

Speed controllers are AI Super Reverse Digital controllers. (I have tried several different types of AI controllers with no affect on the behavior I am about to describe.) These controls self-calibrate them selves to the transmitter.

Transmitter is a Spectrum DX5e. Only two channels are used with the sticks forward - center off - reverse.

Battery is a 7.4v LiPo.

Here is what is happening: Testing in the shop, everything works great. Power up the transmitter, power up the vehicle, receiver lights up. The vehicle drives forward and back as it should.

When you get to the stage situation, all hell breaks loose. The vehicle might 'boot' with one or both channels inverted (forward stick reverses that motor). Or it might boot normally, drive correctly for a while, and spontaneously have one or both motors reverse the controls. Once in a while one motor/channel might go completely dead. The net of it is that the vehicle is spontaneously uncontrollable.

The one thing I know is that everyone there has a cell phone, so perhaps whatever this is is exacerbated by interference???? Or are the receiver/controller.motor components mismatched? I feel confident that the problem is not any loose connections or an undercharged battery.

My first posting, thank in advance for your help.