I screwed up 😶 toasted connectors **update**

Ok, I pointed out a few hiccups I had when I accidentally put together a xt60 to xt90 and wasn’t really thinking when I put on the xt60 on the polar opposites. Then I plugged both balance plugs in for the two batteries, plugged the screwed up connector in first, then when I plugged in the regular one it sparked all over, and quickly unplugged it. The connectors were charred up, and I can’t really get a great connection between them anymore. 4 balance connectors burnt off, but I checked the voltage on all of my batteries and they were all the same. Taking off the case would be a lot of work, so I’m wondering if it would be worth it. I’m wondering if this has ever lead to anything bad, I come from the world of multicopters and know it is better to be safe than sorry, but it’d be a big expense to replace the batteries.

ya ive toasted my connectors before its not fun, and its scary… there are people on here that can guide you through fixing it… replacing xt60 is easy but the balance cables might take a little more effort… I wouldnt give up the picture doesnt look that bad… im sure your batteries are fine, just work slow once you have the replacement connectors

You can definitely repair these just a matter of the time and care you’ll have to take while doing that vs the actual cost of the batteries. You can buy new balance cables with the connectors already attached, but in my experience you also need aluminum solder and flux to easily solder to the battery tabs. You might get away with reusing the solder already on the tabs but if it drops off or comes off with the wire good to have some around (regular solder without flux doesn’t stick to aluminum for crap)

If you short the main discharge leads while replacing the main plug that would be the biggest danger point since if you short those you have a path that can deliver a lot of current so will make another heat and light show.


If you decide to do the repair just remember to only cut or work on one exposed wire at a time to avoid more shorts.

definitly agree with you, only cut/work one at a time or POOF!!

Should I check and see if the main leads are loose? Is that a serious possibility?

There’s a chance the solder started to cook off of the mains leads or some of the balance leads where they connect to the battery tabs but I’m guessing those balance lead wires are fried most of the way through, they likely left around the rubber/silicone sleeve but the inner copper core is likely toasted out of there so you probably need to replace those wires from the battery tabs anyhow.

Ok, update: I’m realizing my enclosure for the batteries might not have been the best idea. I opened it up, and here it is:

I see a rip in one of the plastic heat shrinks. It is one of the ones that shorted, but the one battery that was not involved in shorting, looked very similar. I’m sure I could clean up and maybe wrap it in a soft rubber or something. I took a look at the balance leads and a few are completely friend, and it looks like I need to replace the leads on them. Is that where the aluminum solder comes in? I’ve never heard of that type. Can someone recommend a brand?

Here’s what I found: Alpha Fry AM53718 Cookson Elect Lead Free Aluminum Wire Braze Solid Wire and Flux Kit https://www.amazon.com/dp/B000G31NWU/ref=cm_sw_r_cp_apa_5PLDzb1YV48WR If I have the balance leads, and this aluminum and flux, I should be fine with soldering the lipo tabs?

Yeah if you carefully cut and peel back the plastic around where the main leads and balance wires go into there you’ll see the individual cells are connected to each other with little “tabs” for lack of a better term that are soldered together and have the balance wires soldered into the connections.

After they solder them they fold them over and cover with foam and some kapton tape usually so you have to take all that stuff off (be careful you don’t want to further damage a cell by poking it hard or squeezing it or anything). Once you have the plastic off and the kapton tape and foam off the tabs you’ll be able to bend the tabs out a bit (be careful they can break off the cell and then it’s pretty much toast), pretty sure the foil is aluminum because I tried soldering things to it with regular solder and wouldn’t stick at all got some aluminum solder that came with flux and it worked really well (still sketchy working with the soldering iron by the battery but it works).

Stuff I have is called UNI-4300 I just searched amazon and got one that looked promising it worked well.

Regarding soldering onto the tabs, unlike the 18650 packs soldering onto these tabs is the regular way of connecting them, you’ll see a blob of solder from the factory on there, but you still need to be careful not to overheat the packs, heat is the enemy batteries.


Regarding the pack getting scraped up make sure there aren’t any blow out holes in any of the cells but if the voltage looks good on all of them you’re probably fine. I got some roll of foam sheets that you can tear off and just wrap my batteries with that and has some extra cushion from the thick duck tape lining my enclosure.


https://www.amazon.com/Uniweld-P4KD9S-Aluminum-Solder-Applicator/dp/B010UMSB9Y/ref=sr_1_2?ie=UTF8&qid=1500929400&sr=8-2&keywords=uniweld

^^ got that stuff, more $$$ but it did do the job pretty quick


Also already lots of warnings but if you decide to do this make sure you are very cautious and deliberate about what you’re doing and be ready to just dedicate some time to it and have safety gear around. Glasses so you don’t splatter some hot solder in your eyes, something to drop the battery into if it blows into flames, have an ammo box or other metal container big enough to easily throw the battery into near by and ideally sand to dump on it in the worst case scenario… I had a fire extinguisher around but honestly that won’t do much except stop it from burning too much stuff around it.