None of my solder joints stick to xt90 connectors

Hi team, been trying to redo a solder joint and have spent 2 hours already and cant get the wire to bond with the xt90 conector! It sticks to the wire, but it literally will drip off the connector. What gives? Any insight?


1 Like

Did you use any flux?


Plenty of heat… a small iron won’t cut it.


Youre using flux core solder which means you just need more heat. Tin both ends. Melt together.


Can you take a picture of the solder iron you are using? I can almost guarantee that it won’t get hot enough to solder wire of that gauge. To get the best adhesion you also need to heat up the wire, not just the solder.


tin the wire with solder, full up the pin with solder to the half, heat it up till it stays liquid for some seconds and than just stick the wire in the hot solder filled pin. Should work like this

Prime the xt90 with solder first. Also disconnect the plug so heat isn’t lost to the other end and to the wire on the other end.

Definitely need to tin both sides first. Especially on the xt 90


I was told to leave them together to keep the Connectors true and straight

1 Like

You can plug into a new one without wire soldered to it is what I meant.


Yes keep them together Put the wire on the connector “slot” and press it with a soldering iron

Also maybe you can get a bigger tip

20min ago I menaged to solder a 29mm2 cable with a 40w soldering iron perfectly


1 Like

Watch this:


Just from the look of that broken connection it seems untinned. You don’t use the solder to bridge the two together, you solder the connector and the wire individually, making sure the solder sinks into the wire properly. Then you put them together and apply the solder to them so that they both melt at the same time and “fuse”, then remove the iron and hold a sec to allow the joint to cool.

1 Like

Lots of heat and just drip the solder in over the wire untill the cable is surrounded in a nice little tin bath. When it’s all in and surrounds the cable heat it all up so it becomes fluid again. That way you won’t have cold solder joints.

Don’t worry about the heat. It will be a nice learning procedure when you melt your first xt90 connector :smiley:

Just watched the whole 9 episodes. Actually full of good information, this should be put in the beginners wiki for those first time solderers!

It’s a GREAT intro to soldering. Should be mandatory viewing IMHO.

1 Like

Hey guys thanks for all of the fast responses, i think more heat is the solution, i maybe didnt make it clear that its my solder that wont stick, i can tin the wire easily but when i try to tin the xt90 connector the solder literally just balls up and falls off.

Sounds more like a dirty connector to me, did you pre clean the surface with IPA/rosin or acetone?

photo of your soldering iron? bigger tip helps a lot