Long ESC-lipo connectors?

[foxkilo]

I've read before that using long ESC-lipo wires will tend to kill the ESC rather quickly due to inductive voltage spikes.

But in some electronic arrangements like for EDF, it is unavoidable to use these long wires because the lipo sits at the nose end while the ESC usually buried in mid-fuselage near the fan.

My questions are:

How long is too "long" before the inductive effects are significant? (ok, sounds funny... but basically what's the longest wires you have used without observable effects on the ESC.)

How to reduce this effect? I've got suggestion of using capacitor in parallel to cancel the inductive effect - but would like to hear from practical experience.

Thanks.

[nicedude]

The one that gets damage is the input capacitor due to increase inductance.

Simple solution is extend the motor wire and twist the cables to prevent interference.

[foxkilo]

Thanks for the pointer.

I'll try twisting the wires for inductance cancellation. I can't extend the motor wires because in my case, the ESC got to sit up in the nose for balance, sharing cowl space with the motor. It's a E-flite Hawker Sea Fury, by the way - and that's the way the ESC is mounted in the manual.

[nicedude]

Twisting the lippo wire wont solve the issue, the problem with long wire is inductive voltage spike will kills the input capacitor. Twisting is to reduce interference.

If you cant extend motor wire, the other solution is adding more capacitor in parallel with the current input capacitor.

[Super-Hornet]

Ehh... I not sure about inductive or capacitive that kill ESC....but based on electronics point of view:

If 2 wires (positive and negative...like signal or power wire) running in parallel and over a long distance or long cable, the wire running parallel will have more "Capacitive" behavior/effect instead...not inductive.
The reason is that, when two conductive wires carrying positive and negative signal and running in parallel together, they behave like a long strip of conductive and separated by dielectric (in this case, air and insulator).
That is actually how a capacitor is created. Thus, u have MORE capacitive effect instead.

To produce inductive effect (or to create inductor), a single wire have to be coil in a circular manner. Thus, if u coil the wire together, you produce more inductive effect.

As for twisting wire, the twisting wire will cancel off each wire EMF effect and thus, reducing EMF noise.

SH

[dt2133]

This is an interesting topic. Actually when two cables are twisted together, it will have both inductive and capacitive effect.
Yes, when the cable get longer, the capacitance is more. But, only up to certain length. Above a certain length (depending on
the frequency), both the inductive and capacitive effect will remain constant even if the cable is longer. This is called
transmission line effect.

Now, your problem (when cable length is too long) is not so much to do with the inductance or capacitance. It is more to do with
the resistance of the cable. When the cable get longer, the resistance is higher, and so the voltage drop on the cables (both
positive and negative) will get higher. This will result in higher voltage spikes on the power line.

The idea is you should make the cable as short as possible. If at this shortest possible length, it still give you problem. Your
only choice is to use a thicker cable (i.e. lower AWG wire).

[perfect1]

.......

My ESC to Lipo wire is about 50cm long. If i will to add capacitors, what value of capacitors should i use?

[foxkilo]

Just to update, since I started this thread.

I extended the lipo end of the ESC wires (Hobbywing 40A) another 8 inches in addition to the stock length.

Used in my Sea Fury... flies happily ... 5 takeoffs... and equal number of landings , no excessive heat or weird happenings.

[perfect1]

Just to update, since I started this thread.

I extended the lipo end of the ESC wires (Hobbywing 40A) another 8 inches in addition to the stock length.

Used in my Sea Fury... flies happily ... 5 takeoffs... and equal number of landings , no excessive heat or weird happenings.

I think I should shorten the lipo-esc wire instead of adding capacitors. Currently the shortest length i can go is still about 25cm.

[perfect1]

....

Did a stactic test using full throttle for 3min plus using hobbywing 60A ESC. The ESC was 37deg c and the capacitor is 40 deg c. Using half throttle the temp on the ESC is slightly higher.