maybe im doing something wrong but every time i have to solder a new xt60 onto a pack i end up with either a cold joint or i overheat the connector and it starts warping slightly. ive got a decent iron, hakko fx-888d, and im using 63/37 rosin core solder which i thought was the good stuff. tinning both surfaces first, trying not to hold the iron on too long but also need enough heat to get proper flow.

the lipo tabs themselves are fine, its specifically where the wire meets the xt60 cup that i keep struggling with. sometimes it looks ok but when i do the tug test it feels a bit sketchy. been doing this like 6 months and built probably 4 or 5 quads at this point so not a total beginner but this one thing just keeps bugging me.

hakko 888d is a great iron so its not that. my guess is your tip is either oxidized or too small for the job. xt60s need a lot of thermal mass to get the cup up to temp fast enough that you can flow solder before the plastic starts caring. i use a big chisel tip specifically for connectors, way more contact surface. also crank the temp up, like 380-400c, get in and get out fast rather than babying it at lower temps for longer. lower temp just means youre sitting there longer and thats what actually warps connectors.

yeah xt60s are annoying, i always pre-tin the cups way more aggressively than feels necessary, fill them almost halfway with solder before the wire even goes near it. then when you push the wire in and touch the iron it just flows together instantly. also are you using a third hand or some way to hold the connector still while you work? trying to hold it with pliers and solder at the same time is a nightmare and usually how you get those sketchy joints imo