Solder my 60/40 radio shack stuff

[999zip999]

It's been melting letting go of 4mm bullets gold plated H.K. stuff. At 72v 30amp lyen controller and and 20s 6p 21700 Samsung cell .Mxus 4t 3,000 ?
Why is solder melting ?

 

[amberwolf]

poor connection between connector contacts.
resistance of connector is so high it acts as a heater
so high in this case it reaches hundreds of degrees, enough to start a fire

replace connectors with better-connecting ones, and that are also appropriate to the current being used.

 

[999zip999]

Should I use a higher temp solder or do I have a false pos. As I'm only running 2,200 watts ??? On a mxus 3,000 4t. Could my phase wires have a false pos ?

 

[liveforphysics]

60/40 solder is fine solder.

Your goal is to get the copper conducting elements in your joint as close as physically possible to each other before soldering. This is because the solder itself (all types) are terrible electrical conductors compared to copper.

 

[gobi]

op, pls watch this

https://www.youtube.com/watch?v=qEdysiZAYZ4

can you measure the ohms across your connectors (both + and - individually) please

 

[JackFlorey]

Should I use a higher temp solder

No! That solder melts at 360F. If it is melting and causing a disconnect, it is saving your wiring and connectors from overheating and/or catching on fire.

Fix your resistance problem.

 

[4πr^2]

60/40 solder is fine solder.

Your goal is to get the copper conducting elements in your joint as close as physically possible to each other before soldering.

Yes, good point. Plus there is a whole art to soldering. Ideally, the wire would have a mechanical joint such as a crimp, dog-leg through a hole, a twist, or some inter-wire brading. The solder would then secure and enhance electrical conductivity of that mechanical joint.

Several considerations:

What is your wire size and is it compatible with the amps you want to run and the connector you're using. Too small wire will obviously heat up no matter how good the solder joint. But too big of wire might not fit properly in the connector and can create a high resistance joint.

Is the wire and connector clean, non-oxidized before soldering? Often solder won't 'wet out' on oxidized copper. Copper should be bright and clean before the process is attempted.

Are you using plenty of flux? For tiny electronics joints, 'flux core' solder is often enough. But for large wire joints, you should ideally paint the joint with flux before soldering. This keeps the copper from oxidizing while heating which can then create issues mentioned above. Flux also has some cleaning effect in case the copper wasn't spotless to begin with - though don't count on it blasting off heavy oxidation.

Is your solder iron big enough to heat the whole joint? Ideally, your solder would flow like water through the strands of copper wire and fully 'wet' the joint. Cooling into a smooth/shiny surface. If you are getting a 'pasty' or 'grainy' surface, or can only melt small blobs of solder at a time, then your iron doesn't have enough capacity. If doing large joints, a small torch can come in handy for extra heat - but then flux is critical to prevent oxidation.

What size (diameter) solder are you using? If you have relatively small diameter solder (for electronics work), but trying to solder a large joint, sometimes you can't feed the small stuff in fast enough. Possibly use larger diameter solder, or take some of the small stuff and fold it double/triple/quadruple/[or more] over itself, then twist it together to form one large 'stick' of solder.

Are you letting the joint cool completely undisturbed? Large joints/connectors can take some time (minutes) to cool down. If you bump or pull on the wire before then, you can make a pasty / high resistance joint.

Probably a dozen more things, but hopefully some things to consider.

 

[999zip999]

Lyen 9 fet phase wires from controller grn-grn, blue- yellow, yellow- blue the melted one.. Hall wires grn-grn, blue-yellow, yellow-blue. A time ago one of the phase 4mm connectors had melted apart. So had replaced with 5mm H.K gold plated ones.
Now taking apart I found the melded bullets were loss, yes the one that melted. No I don't remember which one melted before. I looked up radio shack 60/40 and melt point 477f. ??? What temp should I set my Weller 101 for 5mm or use the Weller 80amp iron ? Thanks for the help.

 

[Eastwood]

Yep as live for physic mentioned you need to have both surfaces at equal temperature when soldering. If not it creates a superficial bond which would disconnect like you’re saying with heat. Amber Wolf brought this to my attention a few months back and it makes perfect sense that both metal objects need to be similar temperature for the solder to bond well.

Are you using extra flux?






We all love you AmberWolf, we’re all rooting for you sir!

 

[999zip999]

Yes this one looks crooked this is the wire for the motor side the other side is the melted Yellow 5 ml connector

I will resolder yes have radio shack flux.Flux.
Maybe use these ? And 80 watt iron

 

[999zip999]

Ok resolder the blue as it was seated wrong and a new 5mm on the yellow wire. I hit it and turbo works so much better. Yes it show 2,200 watts on the C.A and goes up the test hill a lot faster. Like it Zips.
Thanks guys I also think the color combo is correct also right.

Yes I thought I had the wire combo wrong for 2,200 watts

 

[Eastwood]

Nice, good to hear :thumb: