Boyntonstu
10 kW
I have made many solder connections to 18650 cells but I have recently found that some brands will not solder.
Has anyone found a way to solder these stubborn cells?
Has anyone found a way to solder these stubborn cells?
18650 cells that are unsolderable.
- Thread starter Boyntonstu
- Start date
Chalo
100 TW
You'll need a caustic flux to match whatever alloy the terminals are made of.
Between the unpleasantness of working with such a flux, and the inconvenience of cleaning it all off, you may find it's better not to bother with cells like that. If they're not tabbed, you're probably damaging them anyway.
Between the unpleasantness of working with such a flux, and the inconvenience of cleaning it all off, you may find it's better not to bother with cells like that. If they're not tabbed, you're probably damaging them anyway.
Boyntonstu
10 kW
This 1 minute video may change you thinking about soldering the positive terminal of an 18650.
https://www.youtube.com/watch?v=SpKSewcqdgU
[youtube]SpKSewcqdgU[/youtube]
The easy solder 18650's look like my new "6 pack battery on a stick" design shown at the bottom of this post.
A hose clamp with hold the positive leads tight to the negative cans above as it gathers the 6 pack cell onto the dowel.
There will be a disk insulator between each 6 pack.
The result will be an easy access, easy removable cell battery.
[moderator edit to fix links]
https://www.youtube.com/watch?v=SpKSewcqdgU
[youtube]SpKSewcqdgU[/youtube]
The easy solder 18650's look like my new "6 pack battery on a stick" design shown at the bottom of this post.
A hose clamp with hold the positive leads tight to the negative cans above as it gathers the 6 pack cell onto the dowel.
There will be a disk insulator between each 6 pack.
The result will be an easy access, easy removable cell battery.
[moderator edit to fix links]
Boyntonstu
10 kW
riba2233 said:
The 6 pack on a stick will be an easy cell access, easy removable cell battery.
Soldering a wire with a 40 Watt iron is cheap, fast, and reliable.
A hose clamp is cheap, fast, and removable.
The dowel makes for a very versatile mounting method.
After you weld up a brick of cells, how do you remove one?
Does Tesla Motors weld their 6831 NCR18650 Panasonic batteries in the "Battery pack"?
rscamp
1 kW
The video shows the wrong tool and the wrong method for the job and results in heat being applied at least 4X longer than necessary. Instead, after preparation coil up the total amount of solder required on top of the battery and use a hammerhead tip.
Boyntonstu said:
40 w?? only? that must take a really long time to heat up, poor cells. And yeah, tesla does weld their cells! It's actually 7104 cells. They do it ultraconically. these cells are so reliable that you'll never have to unweld or something like that.
Alan B
100 GW
Depending on the plating they use, soldering might not work well at all. Since soldering is not recommended by the manufacturer, they have no reason to use solder compatible plating on the contacts.
It would be better to get the proper tooling for the job (a welder), lithium batteries are dangerous enough without this.
It would be better to get the proper tooling for the job (a welder), lithium batteries are dangerous enough without this.
Boyntonstu
10 kW
Alan B said:
The cells that I use are from old laptops and they are expendable.
Many DIYers use solder to connect their cells.
Look at the huge iron that Rinoa uses.
[youtube]https://www.youtube.com/watch?v=Rjr2LKmhdVw[/youtube]
Alan B
100 GW
That doesn't mean that it is a good idea, or that it should be done. Soldering may block the pressure relief valve and turn a cell into a potential time bomb.
Just say no to soldering 18650's.
Just say no to soldering 18650's.
Given that many of the 18650 spec sheets out there explicitly say, "Do not solder onto this cell," I'm not really surprised that they're not easy to solder. It's not really a design goal.
You generally don't. Because you typically try to build a pack with high quality, matched cells, instead of building a junk pack. Also, you can easily enough remove the welded tabs from a cell by pulling them free and hitting the remaining points with a file. If you're repeatedly soldering and desoldering to a cell, you're just doing more and more damage to the cell. They're not designed to take that kind of heat. After spot welding a tab to a cell, the tab and cell are barely warm to the touch. I assure you, you don't want to be touching a cell shortly after soldering to it. Given that the LiCo chemistries can start running away thermally around 130C, and standard solders require 180-200C to melt, I'll pass on putting that much heat into the batteries, thanks.
Yes.
That it can be done and work for some limited period of time does not mean it's a good idea. The cell manufacturers say not to do it, and they know more about their cells than anyone else.
Boyntonstu said:
You generally don't. Because you typically try to build a pack with high quality, matched cells, instead of building a junk pack. Also, you can easily enough remove the welded tabs from a cell by pulling them free and hitting the remaining points with a file. If you're repeatedly soldering and desoldering to a cell, you're just doing more and more damage to the cell. They're not designed to take that kind of heat. After spot welding a tab to a cell, the tab and cell are barely warm to the touch. I assure you, you don't want to be touching a cell shortly after soldering to it. Given that the LiCo chemistries can start running away thermally around 130C, and standard solders require 180-200C to melt, I'll pass on putting that much heat into the batteries, thanks.
Yes.
Boyntonstu said:
That it can be done and work for some limited period of time does not mean it's a good idea. The cell manufacturers say not to do it, and they know more about their cells than anyone else.
dnmun
1 PW
laptop cans can push 1A max so there is no need for a 12AWG wire or 10AWG wire some guy was gonna use. i have recommended many times that people use a thin copper link of 1-4mm^2 cross section for these cans, depending on their capacity and chemistry since the newer NCR cans can push up to 10A in a surge it appears.
in this case 1mm^2 is enuff and it would be euff to use a 26AWG wire max to carry the 1A of current the laptop cans can provide safely.
that reduces the amount of heating needed and if you pretin both the serial copper link and the can before soldering then you can keep the heating to a minimum and then as soon as the pretin spot melts and you have reflow then hit it with the wet sponge to cool it rapidly.
in this case 1mm^2 is enuff and it would be euff to use a 26AWG wire max to carry the 1A of current the laptop cans can provide safely.
that reduces the amount of heating needed and if you pretin both the serial copper link and the can before soldering then you can keep the heating to a minimum and then as soon as the pretin spot melts and you have reflow then hit it with the wet sponge to cool it rapidly.
fellow
1 kW
I agree with dnmun, 1mm^2 is enough for one 10A cell. I'm using 0.75mm^2 wire per cell on my latest project (NCR18650PF). On the other side, I do not recommend thinner than 0.75mm^2 per cell, it is the lower limit.
Thin wires can serve as a fuselinks in case something shorts, use always silicone&copper wires.
Thin wires can serve as a fuselinks in case something shorts, use always silicone&copper wires.
E.Engineer
1 µW
- Joined
- Jun 2, 2016
- Messages
- 1
First plate the cell ends with Nickel. Use so called "Woods strike" solution. Premix 500 ml & keep it around. Make a gadget to hold the cell as you only want to plate the ends & don't want cell voltage interfering with the plating process. Immerse sequentially both cell ends ~15 to 30 sec, adjust your PS for at about 25-50 ma to produce about a 20 micron plate. On ss or nickel like surfaces you won't see a thing. Test on brass or copper to if you want to confirm plating action. Woods solution is Nickel Chloride + HCl. A workable solution is 25g Nickel Chloride dissolved in 400 ml distilled water & add ~ 100 ml HCL Acid ( I use pool acid) to yield 500 ml - lasts a long time. Anode needs to be Pure nickel strip. Obviously use appropriate PPE. Plated Cells ends then accept solder very readily.
LewTwo
1 MW
Here is a really stupid question. If one is determined to solder 18650 cell would it not make sense to use a tool that can deliver a lot of heat to a small area very quickly ... like a Welder soldering gun rather than a low wattage iron ?
IIRC in various threads about soldering cells, tabs, etc., it's generally been found good to use large "hammerhead" or "chisel" type tips on ~80-100w irons. The large tip holds a lot of heat, so when you put it on something that sinks a lot of heat, it can dish enough of it out quickly enough to preheat the stuff solder needs to stick to without getting the rest of thigns around it really hot by sitting there too long with the heat source.
