Soldering iron for 18650 packs

I know the consensus here is to spot weld all battery packs with nickel strips however I don’t plan to buy a spot welder at the moment.

I have a high wattage Weller soldering station and I already built a couple of packs which turn out perfect, been using the packs for several moths with zero issues.

I need some advice to solder cells together:

  1. There are no youtube videos showing how to solder 18650s with nickel strips, have you got one with good quality results?
  2. Soldering flexy silicone cables to 18650 cells is much easier to solder nickel strips, is this a good approach or should I stick with nickel strips?

Hope you soldering gurus could give me some input on this.

Just soldered a new pack gonna make it airplane travel safe I recommend wire if u wanna make it flex and it’s easier high strand but u sacrifice space

Are you using 12AWG flex silicone wire?

Can you post a picture of your work?

Nickel strips seem almost impossible to work with a soldering iron

Nickel strips require lots of flux and heat along with some scuffing

My work is in one of my previous threads, I used 12 awg but I don’t recommend that

What would you recommend then?

What size pack are u making?

I’m working on a 10s4p

This is the build of my 10S4P using a soldering iron and nickel strips.

I would say pre soldering the strip helped and plenty of flux was useful. You need to be in and out quick to stop the battery heating up. I hot glued my cells together first and would recommend doing this. You will probably want to reinforce the nickel strip with single core copper across the series connection.




I did some testing on Nickel strips I got off eBay. at 12v 10 amps they got hot, and at 20 amps they discolored and began to fail. At 40-50v 20A I don’t think they will work well at all. nickel (or nickel plated steel like most eBay strips are) don’t conduct electricity well. If you are going for 18650 batteries, it’s probably because you want a premium battery. One that can output a ton of current, so it’s worth making sure all the connections can handle the current. The 12 AWG wires will handle 20A no problem. The 8 AWG will handle 60-70A no problem. Might be able to go to 6 AWG if you have more than 4 in parallel. The concern of soldering batteries I believe is over-rated. As long as you are careful not to overheat the battery, I don’t see the problem.


i just used normal 1,5mm copper wire for my 10s3p and iam happy with that , no issues so far.

But much tbh

Get some 14awg high strand awg and decent flux, some nice solder and a Denzel with sand bit and ur good to go this is what 12awg looks like

How necessary are sticky insulators? And where did you buy the copper braid?

I read somewhere, on Endless Sphere I believe?, a story of a guy’s 18650 pack using nickel strips. When he was using a lot of current from his battery, the strips got so hot they melted through the plastic insulation on the 18650 cells and shorted them out. The picture below shows the positive and negative are actually right next to each other, only separated by a thin plastic insulation. If that’s damaged or melts, the cell will short out.

The idea behind the sticky insulators is that they protect against heated connections, either through the soldering process or thin nickel strips that heat up under high current loads.

The copper braided wire was ordered form McMaster Carr - the link is in my post above. You can also find copper braid from eBay, but I found it’s sometimes a lot thinner and may not be 12AWG equiv.

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Thanks for the quick and informative reply!

Sorry I also forgot to ask of rosin core solder is particularly important, as I do not have access to that at the moment.

My understanding is that rosin core solder is just solder with a type of flux built into it. It helps the solder “stick” to whatever you are soldering. I don’t see a reason why you couldn’t just use flux and regular solder together.

you can totally use flux and regular solder. You can also use flux and rosin core for stuff that’s giving you a hard time.

also… if you buy flux in bottles like i do…

these are awesome. and dirt cheap. and they don’t really seem to clog much with dried flux for some reason.

i got some of these and a solder pot for tinning big wires and now tinning is no longer a hassle. its actually kind of fun watching the flux boil out of the wire as the 50/50 wicks up the 10awg wire like oil in a lamp wick.

The solder pot i got was $20 on amazon too. along with a big bar of 50/50 solder to go in it.