This topic is about the Importance of gold plated connectors and good solder connections on electric RC planes:
All are invited to give their comments and add to the topic as I believe this would be of interest to all.

Lets look at an electric setup of a BL2212-6 motor+ 30amp ESC + 3S1P 2200mah LIPO with a 6x4 prop. The max current can reach easily upto 24amps

Lets do a little maths:
24amps current draw at 12.6v means the ESC + motor + LIPO resistance is :
12.6/24 ohms = 0.525 ohms.

A voltage drop of 1v then requires a contact resistance of
1/24 ohms = 0.042ohms. If your connections have a contact resistance of greater than 0.042 ohms, you are already droping one volt i.e. 8% of your max voltage on the battery. As the battery charge depeletes, this will rise upto 9% when the terminal voltage of the LIPO reaches 11.1v. Below this, it is not safe for the life of the battery

Now we have 3 wires which are connected between the ESC and the motor firing in synchro with the commutation of the motor. If each connection has differring contact resistance, the voltage available  to the separate coils in synch with commutation would differ to a large extent if you do not have a proper connection, and can lead to motor stalling. At any given point of time, two of the connections are in circuit all the time. If each connection has a resistance of 0.042ohms, then you are loosing 2 volts. i.e. 16% to 18% of the battery voltage. Even a badly soldered connection can stop the commutation of the motor because of differences in voltage.

This is the reason why one should take great care of the connection of the electrical joints in an Electric RC model.

Saju

Interesting topic 

Santhosh here was saying that he once had a crash because his soldered connection came lose due to overheating (yes, it should have been prevented in the first place), so he moved to Anderson Powerpole connectors that are of the crimping type.  I guess it would make sense to do the crimping, and then to do soldering on top of that as a best of both worlds approach (safety and good connection) ? 

A proper crimp tool must be used. Don't use a pair of pliers for crimping. I too use Power Pole connectors and I always solder because I don't have a Crimp Tool.

I have been using the Dean type Ultra plug and 3.5 mm gold connectors  for all my models up to 60 size and have not had a problem till date.
But  have had issues with  some bad soldering .

I am not so technically knowledgeable  so not able to comment.

I did have a JST Plug melting on an EDF  and the resultant short  meant the battery was also a write off.
sai

here is the picture of the crimping tool i am using, if the crimping is perfect then there is no need to solder again ,bit difficult when using a powerpole above 30 amps.will surely die for anderson as anwar said


santhosh

Hmmm! So till now we have people who vouch for crimping the connections. Guys did the crimped connections give any lesser performance?

on the contrary properly crimped power poles are better than soldered ones 

 

santhosh

These videos help with soldering deans.  I have forwarded to many newcomers who have found this helpful.





Both show slightly different ways of doing the same thing, and the main ideas remain the same. Use only the correct amount of solder, and minimize the iron contact time.

wow, i never even bothered about resistance loss n stuff i just get some automotive connectors and use them (crimping type)

for 10/- a pair 

The solder that is commonly used for electronics melts at 188 degrees C. I am unable to understand:
1. How the connector became so hot
2. Nothing else was damaged.

More likely, the soldering was bad to start with and just gave way. Good soldering is a skill that has to be acquired.

well one reason i can think of is there was more current draw then the connectors could accept and heated the connector

I believe some other components got damaged also, don't remember all the details.

Santhosh bhai, please comment.

The connector doesn't have to be so hot to melt the solder, but hot enough that the contact gets "loose" and begins to jiggle under the pull of the wire. Or simply a poorly soldered joint.

I connected the battery to the esc in the reverse order, normally we cant connect an anderson in the reverse order,but that was the
big mistake made after soldering, inserted the positive wire in the powerpole's black casing... rest u can guess , lucky to have  no damage because i not crimped the wires, two weeks later the esc damaged may be a resultant of that reverse connection


santhosh

There is a subltle difference in the videos:
Video1: Do not use external flux while soldering. According to me this is a very good method/practice, because the soldering will not take place if the wire or the connector is dirty, untill you sand the surface and make it clean.
Video2: (Big-E-RC)
This uses external flux profusely and is not a preferred method. While this will work pefect most of the time, there are chances that even dirty surfaces can appear to have been nicely soldered due to excessive flux usage.
In any case since we are setting some benchmark, i thought of pointing out the difference
 

This is what I do:

1. Sand both surfaces till they are shiny (a.k.a clean with no grime). This "sanding" can be done with a blade to scrape the surface clean.
2. Tin both surfaces thinly with solder. Remove any excess solder from both surfaces.
3. Contact and apply the iron with some solder for a brief moment.
4. Let cool and then "drain" any excess solder once more.