[Midair]

Last month, while setting up the electronics for my electric 3D Hobby Shop AJ Slick, I had an interesting experience that could have proved to be the demise of my new aircraft. The servos, ESC (a Hacker X-70 Pro) and motor were already installed in the model and the only thing left to do was set-up the servo rates and end points. Rather than hook-up my 2200 mAh four cell LiPo to power the system through the ESC, I decided to simply plug a standard five cell NiCd airborne pack into the receiver’s extra port, but I didn’t disconnect the ESC from channel three (throttle port) of the receiver. It powered up OK, but after about ten minutes of operation the NiCd batt died; not a big deal because I was pretty well finished with the set-up. Anyway, when I did finally hook-up the LiPo I couldn’t get the motor to run for more than a few seconds before it shut down. Also, when I did hook-up the LiPo, the ESC didn’t give me the customary four “beeps” (indicating a four cell LiPo was connected) followed by two “beeps” that I was use to hearing on start up. Thinking that I might have screwed up the ESC programming when I plugged the NiCd pack into the receiver without first disconnecting the ESC, I tried to reprogram the unit using the traditional throttle stick and “beep” method. Although I did manage to get the system to function, I never did get confirmation that the ESC recognised the four cell LiPo. I’ve been flying the model for a couple of weeks, but I was always concerned about the ESC’s ability to read the LiPo cell count, so I ordered a Hacker ESC programmer to reprogram the ESC properly. When the program arrived, I loaded it onto my computer, hooked up my ESC and learned that the ESC would read a four cell LiPo as only a two cell. What this essentially means is that the ESC would have continued to provide power to the motor and servos, theoretically down to 6.4 volts well below the standard motor cut-off voltage for a four cell and not only potentially damaging the LiPo, but, by the time the motor used up all of the power, there would not have been enough batt left to power the servos! The only thing that saved my aircraft was that I strictly limited my flights to five minutes (based on a friends similar set-up) so my batts were never completely used up. The purpose of this rather lengthy post is, first, to warn others to be careful about hooking up a NiCd to a receiver without first disconnecting the ESC; the lower voltage and capacity of the NiCd could screw up the ESCs programming and secondly, I should have confirmed the correct operation of the ESC before flying; I was lucky that I didn’t loose the aircraft, or worse.

Peter

[OLD PRAIRIE RED NECK]

Thanks Midair, I too have used a nicad pack to set up the radio but have always disconnected the ESC first. Why? Didn't know, just seemed like the thing to do.

Now I know why!

[Max]

Thank you for a very interesting report, Peter. I learned something from it. I am glad you took the time to share it with us.

Originally Posted by OLD PRAIRIE RED NECK

Thanks Midair, I too have used a nicad pack to set up the radio but have always disconnected the ESC first. Why? Didn't know, just seemed like the thing to do.

Now I know why!

I have done the same, but never gave it any thought, You can bet I will be more careful to MAKE SURE the ESC is disconnected next time I do this!

[Cougar429]

Were you successful in reprogramming the ESC?

[Midair]

Yes I was. The computer programmer woks well.

Peter