How do i solder this tab?
- Thread starter eikido
- Start date
eMark
100 kW
Soldering on 18650 cell ends shouldn't take longer than 3-4 seconds with the right soldering iron and tip temperature.eikido said:
This is my 2 cents ... FWIW ... if i was soldering the following pack ...
First use an abrasive to prepare the cell ends. Second apply a spot of solder to each cell end. Third apply just enuf solder to fill copper slit (on bottom side) that will come in contact with the previously soldered cell ends. Fourth position the copper plate holding it in place with tape. Fifth solder each copper slit opening to previously soldered cell end using just enuf solder to make secure connection (shouldn't take more than 3 seconds).
Practice on some dummy cells until your soldering techniqque is perfected with secure connections in 3 seconds.
Older ES soldering threads (spot-welding now favored) ... https://endless-sphere.com/forums/viewtopic.php?t=76237 ... https://endless-sphere.com/forums/viewtopic.php?t=74007 ... https://endless-sphere.com/forums/viewtopic.php?t=88166
Another advantage of soldering is easier to make repairs when you need to remove a bad cell and replace with a good cell. It's not that soldering isn't suitable, but rather the skill of the builder. One could contend that whether spot-welding or soldering it all depends on the knowledge, experience and skill of the builder. If both (solderer & spot-welder) are "Master" builders than each technique has its successful application in a DIY 18650 pack build.
https://www.youtube.com/watch?v=CkbKCwelx0g ... https://www.youtube.com/watch?v=XyCTtZ0hRW0
https://www.youtube.com/watch?v=TU0M7QB_Itc ... https://www.youtube.com/watch?v=OtHw-RNyl3g ...
Nice tutorial. I feel it worth emphasizing that the best, lowest-resistance electrical connection is achieved when there is firm contact between the battery-or-circuit-board-or-whatever contact point and the wire or copper sheet BEFORE solder is applied excepting only a thin layer of nicely flowed solder to
'tin" the conductor. Solder should not be the conductor. Best conduction is copper-to-copper. Solder is the "glue" and gives mechanical stability. It has much higher resistance than a tight copper-to-copper joint. Binding or clamping or weighting the elements into solid mechanical contact before final heat and sparing solder is applied is the ticket.
'tin" the conductor. Solder should not be the conductor. Best conduction is copper-to-copper. Solder is the "glue" and gives mechanical stability. It has much higher resistance than a tight copper-to-copper joint. Binding or clamping or weighting the elements into solid mechanical contact before final heat and sparing solder is applied is the ticket.
999zip999
100 TW
Use electrical flux and a damp sponge also good for cleaning tip. Best to have tip tinned as shiny as chrome or just wipe on damp sponge to clean tip
You're not going to be soldering onto a lithium cell, but you still need to solder it quite quickly. If you haven't soldered before, I'd take it to someone who has experience.
The first thing I'd be worried about is what else got damaged when the pack was dropped. I'd check that the metal tab is still attached to each of the batteries with a magnifying glass under a decent light. If not, they're going to need spot welding back onto the relevant cells. How about the opposite end of those cells, are the tabs all ok? Are the main power leads firmly attached. Does the BMS have any damage?
If everything else is ok, normally I'd say bend the end of the tab back towards the PCB (printed circuit board) until it's in contact... but it looks like the PCB track has been peeled off the board, so you'll need to remove the transparent green coating around the rest of the pad with something abrasive and solder something bigger than the missing section across the gap, to be able to bend the tab against it and solder it back down. Some flat copper braided wire might work.
Use a chisel blade tip, clean it, get the hot iron, paint a dab of flux paste onto the two surfaces to be joined. Melt some solder onto the tip, apply heat to the tab and the repaired PCB pad at the same time (they're already touching when you bent the tab into the right position) and feed a bit of solder into the edge where the tab meets the PCB pad. After 2 or 3 seconds, it should start melting and flowing through between the tab and pad. Keep it hot and adding solder until it's appeared all the way around the tab, maybe 6-8 seconds for the whole thing. Remove the soldering iron, and watch that the joint doesn't spring apart. It should look shiny at the end, if it's dull or has a speckled finished, or if it didn't flow smoothly, it didn't work.
Honestly though, given the question you've asked, I think you'd be better off asking at a local electronics company, a school or college, an auto-electrician or see if one of your friends knows how to solder. I hope you get it fixed ok.
The first thing I'd be worried about is what else got damaged when the pack was dropped. I'd check that the metal tab is still attached to each of the batteries with a magnifying glass under a decent light. If not, they're going to need spot welding back onto the relevant cells. How about the opposite end of those cells, are the tabs all ok? Are the main power leads firmly attached. Does the BMS have any damage?
If everything else is ok, normally I'd say bend the end of the tab back towards the PCB (printed circuit board) until it's in contact... but it looks like the PCB track has been peeled off the board, so you'll need to remove the transparent green coating around the rest of the pad with something abrasive and solder something bigger than the missing section across the gap, to be able to bend the tab against it and solder it back down. Some flat copper braided wire might work.
Use a chisel blade tip, clean it, get the hot iron, paint a dab of flux paste onto the two surfaces to be joined. Melt some solder onto the tip, apply heat to the tab and the repaired PCB pad at the same time (they're already touching when you bent the tab into the right position) and feed a bit of solder into the edge where the tab meets the PCB pad. After 2 or 3 seconds, it should start melting and flowing through between the tab and pad. Keep it hot and adding solder until it's appeared all the way around the tab, maybe 6-8 seconds for the whole thing. Remove the soldering iron, and watch that the joint doesn't spring apart. It should look shiny at the end, if it's dull or has a speckled finished, or if it didn't flow smoothly, it didn't work.
Honestly though, given the question you've asked, I think you'd be better off asking at a local electronics company, a school or college, an auto-electrician or see if one of your friends knows how to solder. I hope you get it fixed ok.
eMark
100 kW
There's enough length of that wide/thin tab going to the cell that will serve as a heat sink to lesson heat reaching the cell. Also the copper cell connection itself will act as a heat sink. With the proper soldering skill and equipment that broken tab soldering repair shouldn't have taken more than a few seconds resulting in a shinny/gloss silver surface. From the looks of the bottom photo way too much time was spent soldering and still resulting in faulty repair.
The same tab (corroded) by the lettering BC2 in top photo should have first been thoroughly cleaned with Dremel using a sanding disc and/or abrasive bit. From the looks of that same attempted tab repair (bottom photo) a cheapy soldering iron was used that wasn't hot enuf with the wrong tip. Looks like way too much time was spent trying to do the solder repair in the bottom photo. Thus his concern for too much heat reaching the end of the cell.
It's obvious from the bottom photo it's a poor soldering job as it isn't a smooth silvery shinny surface. Will now be even more labor intensive redoing to fix the poor soldering.
Need to have someone with the know-how and proper soldering iron to fix that faulty repair. Shouldn't mess with it any more ... instead have an experienced qualified technician with the know-how and right tools.
The same tab (corroded) by the lettering BC2 in top photo should have first been thoroughly cleaned with Dremel using a sanding disc and/or abrasive bit. From the looks of that same attempted tab repair (bottom photo) a cheapy soldering iron was used that wasn't hot enuf with the wrong tip. Looks like way too much time was spent trying to do the solder repair in the bottom photo. Thus his concern for too much heat reaching the end of the cell.
It's obvious from the bottom photo it's a poor soldering job as it isn't a smooth silvery shinny surface. Will now be even more labor intensive redoing to fix the poor soldering.
Need to have someone with the know-how and proper soldering iron to fix that faulty repair. Shouldn't mess with it any more ... instead have an experienced qualified technician with the know-how and right tools.
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