Servo testers power supply

[Catfish Will]

I am new to R C and recently got a servo tester.  I connected it to an ESC which was connected to a battery.  This set up worked.  I purchased a four cell AAA battery box and soldered an end off a servo extension matching the positive and negative ends.  It would not turn on the servo tester. The lead from the ESC has three wires with the outside wires the positive and negative.  The battery box only has two leads which I connected to the positive and neg..  What is the function of the third wire on the ESC? Is this why the battery box will not work the servo tester.

[OV10]

RE: Servo testers power supply

Hello Catfish,
Welcome to the forum.
Would really like to give ya a complete answer but without knowing what brand of servo tester you have the only thing that I can respond to for sure on is with regards to your question "What is the function of the third wire on the ESC?" The center wire which is red will be the voltage supply wire(+Vc). The two outside wires are brown or black(ground) and yellow or white(throttle signal control to receiver).
Now if your servo tester is like most of the brands I have used the power connection is usually three pin with the center being +Vc(power) and one of the outside pins being ground and the other outside lead nonfunctional(usually the appropriate pin is labeled + and -). If your tester was of this configuration when you plugged it into the ESC then the tester may have been being power in a reverse loop from the ESC(the yellow/white signal wire served as a ground) and may have possibly damaged the ESC. If you had it plugged the other way around (red and black/brown) then you shouldn't be concerned. Please check you ESC prior to using it on a plane for proper function.
If your tester is as I described then all you have to do with the battery box is make sure that the positive and negative leads location in the connector match that of the pins on the tester. Hope  this helps.
Best Regards,  

[Grossman56]

RE: Servo testers power supply

Heck, I just purchased an adaptor, works great on my GT Power servo tester

Grossman56

[rc4ever]

RE: Servo testers power supply

What i did was velcroed a 2s 1000mah to the back of the tester and spliced the power and ground to the main lead, now can turn on the tester at anytime, and if the lipo gets low i charge it with my charger. real easy done