QS8 connectors smoke

[kaiserbasher]

HI,
i soldered QS8 to my zee 5200 100C 4S batteries and ESC. Before i used EC5, everything was fine with same batteries, same ESC, everything same.
When i tried to charge one of the batteries made troubles, could only charge over balancers (0.1A)

Voltage was 3.99V on all 4 cells at the "broken" one, the good one showed 4.19V on every cell.

Then i gave a try putting them in my limitless (series). ESC (XLX2) started and gave me green signal LED, but no real 8S power came out of system.
After a couple of seconds i recognized smoke is coming from QS8 connector.
Batteries were connected for maybe 10seconds, i immediately unplugged

I double checked poles maybe 100times, double checked cell voltage 100times, maybe i'm blind, but still clueless ...
any ideas?

 

[Starfox2005]

Maybe it doesn't have a secure connection?

 

[kaiserbasher]

Maybe it doesn't have a secure connection?

no way to plug them wrongly, or what you mean with secure connection?

 

[Starfox2005]

Like the wires are some how moving around. Causing a bad connection?

 

[3d-rc.myshopify.com]

I recently had an issue with mine. Solder didn't stick well enough. I didn't have my iron turned up hot enough

 

[KingKeif]

Like the wires are some how moving around. Causing a bad connection?

This was my thought as well.

 

[Adiabatic]

A bad solder joint would explain all your symptoms. It won't charge because the high resistance of the joint causes a large voltage drop in the circuit at charging amperage. Similarly, you get a status light on your ESC because there is a complete circuit, but when you apply throttle and the motor tries to draw power from the battery, current surges through the high resistance joint, the voltage in the circuit drops and instead of going to your motor much of the power is dissipated as heat at the bad joint, causing the connector to smoke.

 

[kaiserbasher]

problem found, as a software guy i would call it a layer8 issue, user was too dumb.

Lessons learned: when dealing with that much power, don't hurry, take your time and allways properly plug your connectors:

thanks for all your answers and sorry for beeing dumb. But blood preasure reached a normal level again

 

[Exc3l]

problem found, as a software guy i would call it a layer8 issue, user was too dumb.

Lessons learned: when dealing with that much power, don't hurry, take your time and allways properly plug your connectors:

View attachment 176074

thanks for all your answers and sorry for beeing dumb. But blood preasure reached a normal level again

That was the issue? When I am testing rigs I never do a full connection just in case smoke goes up.

 

[Adiabatic]

That will do it, I suppose my explanation still holds but it wasn't a bad solder joint causing the high resistance, it was poorly mated connector pins.

problem found, as a software guy i would call it a layer8 issue, user was too dumb.

I like to call those PEBKAC.

 

[kaiserbasher]

That was the issue? When I am testing rigs I never do a full connection just in case smoke goes up.

yes, same idea here, if smoke goes up, be able to unplug quickly ... but don't give full throttle then

That will do it, I suppose my explanation still holds but it wasn't a bad solder joint causing the high resistance, it was poorly mated connector pins.

for sure you are right. I even measured resistance on all my connectors anc cables wherever it is possible. Also checked everything for short circuits.

If you are interested i can post the ohms of my measuring points, to be honest i got surprised

 

[kaiserbasher]

good

not so good

 

[Engineer]

good

not so good

Kind of jumping into this without reading the prior messages - but by "not so good" are you reading the value of the anti-spark resistor in the connector?

 

[kaiserbasher]

yes

 

[K-BASH]

With the xlx2 better be careful.it'll go up in smoke if you have bad connetions.must have good sodered connections

 

[SrC]

Food for thought...
The QS8's have internal resistors to prevent sparking when connecting. They can go south easily with excessive heat and just fail.
Short of a poorly soldered "Cold joint", I cant see anything to be the issue.
You need a very hot iron ( over 600F) with a large Blunt tip iron.
Soldering needs to happen fast. Flux paste can hasten the speed of soldering also.
My thoughts..

 

[K-BASH]

Food for thought...
The QS8's have internal resistors to prevent sparking when connecting. They can go south easily with excessive heat and just fail.
Short of a poorly soldered "Cold joint", I cant see anything to be the issue.
You need a very hot iron ( over 600F) with a large Blunt tip iron.
Soldering needs to happen fast. Flux paste can hasten the speed of soldering also.
My thoughts..

I have lhs soder my hi power connectors.8awg is hard to get hot enough without high dollar sodering systems .I've burnt up 3 xlx2.CC rep said from my $HITTY SODERING.ive learned my lesson,lhs guy has a hard time sodering 8awg with good soder gun

problem found, as a software guy i would call it a layer8 issue, user was too dumb.

Lessons learned: when dealing with that much power, don't hurry, take your time and allways properly plug your connectors:

View attachment 176074

thanks for all your answers and sorry for beeing dumb. But blood preasure reached a normal level again

I did the same thing charging a qa8.not plugged all the way in.was smoking.melted the inside,was very hard to clean burnt plastic out.

 

[Adiabatic]

8awg is hard to get hot enough without high dollar sodering systems

Get one of these, works well for large wires and connectors and under $40USD.

 

[kaiserbasher]

I have lhs soder my hi power connectors.8awg is hard to get hot enough without high dollar sodering systems .I've burnt up 3 xlx2.CC rep said from my $HITTY SODERING.ive learned my lesson,lhs guy has a hard time sodering 8awg with good soder gun

I did the same thing charging a qa8.not plugged all the way in.was smoking.melted the inside,was very hard to clean burnt plastic out.

for EC5 and QS8 i use a 120W iron, bought it for 20€. But you can have bad luck with it

 

[Spoc85]

I have lhs soder my hi power connectors.8awg is hard to get hot enough without high dollar sodering systems .I've burnt up 3 xlx2.CC rep said from my $HITTY SODERING.ive learned my lesson,lhs guy has a hard time sodering 8awg with good soder gun

I did the same thing charging a qa8.not plugged all the way in.was smoking.melted the inside,was very hard to clean burnt plastic out.

I have lhs soder my hi power connectors.8awg is hard to get hot enough without high dollar sodering systems .I've burnt up 3 xlx2.CC rep said from my $HITTY SODERING.ive learned my lesson,lhs guy has a hard time sodering 8awg with good soder gun

I did the same thing charging a qa8.not plugged all the way in.was smoking.melted the inside,was very hard to clean burnt plastic out.

Give this flux a crack