BocaBen

I ran a quick experiment today as my Futaba BR-2000 voltage tester indicated a 0.5V difference between being plugged directly to the battery, or after a JR HD switch. My first impression was that the switch was bad but after evaluation, it seems like the connectors are the problem.
The battery is 5.97V (under a 2 Amps load)
Voltage after the connector, but before the switch is 5.43V (or a 0.54V drop) after a 3" pigtail.
Voltage after the switch is 5.40V (or a 0.03V drop)

Seems like a bad connector but again, using a standard 250mA load would have shown much less of a voltage drop, and made this problem invisible.

So, solder whenever possible and reduce the number of connetors to a minimum.

Ben

Rodney

You have just proven to yourself the value of good connectors. Use gold plated whenever possible and make sure there is no corrosion or dirt on the contacts. Bad connectors are probably the biggest problems evidenced by jittery servos, glitches etc. that often get overlooked. Switches are also critical for the same reasons.

BocaBen

The problem resides in the connector crimping, which with the age, became corroded.
I removed the plastic case and found that the copper wire at the crimp was dark brown on both the battery and switch side.
Just out of curiosity, I placed some liquid flux and soldered the 4 crimping areas (M/F positive & M/F negative).
The voltage at the switch went from 5.43V (before soldering) to 5.93V (after soldering)
PROBLEM SOLVED!

Lesson: I will solder all my connectors crimp from now on

rajul

My Feedback: (58)

Its a good thing that you stopped to analyze the situation. This saved you from a potential crash. Well done! Another thing you might want to consider is heat shrinking the connector joint to protect it from contamination and accidental loosening

BocaBen

Well, you generally feel better when you don't know about a problem (stick your head in the sand)!
I have so many connectors/extension to look at that it is not funny (9 models).
I will not feel comfortable flying now that I know this potential problem, which I am sure is latent in my other planes.

I always bought HD extensions from JR or Futaba (not the cheap stuff), but I come to realize that those are not better from a crimping standpoint.

Rodney

As to crimping versus solder, a rather extensive test in the commercial world has proven that a good crimp is far more reliable than a good solder joint. Note the word "Good" as all crimps are not good. Properly done, a crimp will outlast and outperform the solder joints. In our little world of RC though, I still prefer the soldered connections when I do it myself. As to putting heat shrink over a crimped joint, this will not help, in fact may be a detriment as it prevents visual inspection at a later date and is not total protection from corrosion.

JPMacG

My Feedback: (2)

There are all sorts of variables and it may be misleading to gereralize that crimps are always better or solder joints are always better. I expect it has to be examined on an application by application basis. For example, I expect that solder joints are more susceptible to stress fatigue. I expect that crimped joints are more susceptible to galvanic corrosion.

I like to solder RC connections whenever possible. I even flow solder over the crimps of Futaba J connectors, although I'm not really sure this is a good thing.

richrd

Interesting views I know that military de-rates crimps and NASA is also not fond of them. If low skill people are manufacturing then crimp is best in consistency, also crimps usually have a strain relief built into their crimps. As for soldering it has the lowest Resistance over time and over all will corrode much slower if ever at the wire joint.
BTW … I also solder all of my crimps in RC and other projects that I intend to last forever.
Rich

BocaBen

I use some citrus based liquid flux with a needle dispenser, very little qty is required.
I then tilt the connector upward about 30 degrees as for the gravity to push the soldering toward the cable and not the golden plated connector side.
Very quick heat, apply little bit of solder (thin wire), remove the heat and let it cool down.
The flux will help the soldering to flow all over the wires and the crimp area.
I then use a couple drops of rubbing alcohol to remove the remaining flux and clean the connector.

The real trick is to remove the connector from the plastic housing without damaging those little plastic tabs.

Geistware

My Feedback: (16)

Did this test a while back and that is why I use Deans connectors everywhere except the servo.

BocaBen

I am actually thinking about using Dean connectors as well between the battery and the switch.
Now, this means that the 'weakest link' becomes the connector plugged in the Rx, which is only rated for 3 Amps.
If I have a single battery going to a single switch (small size airplanes), I will then add a second lead in parallel between the switch and the Rx. This will provide redundancy and a reduction of the resistance as well.