Batteries: easier soldering with flat to button top conversion

I just found these on ebay: Magnetic adapters to convert from Flat to Button Top

Does anybody know what kind of current these can handle? Because this could make soldering custom packs even easier and less dangerous - you just solder the wires to the magnet and put it on the battery after all the soldering is done. Not sure how bad vibrations are for this type of connection though.

Soldering to those magnets would be pretty much impossible. Also the heat would damage the magnet’s magnetizing abilities, making it weaker

Well seems like there are mixed experiences with this type of thing. Not easy but doable - but I guess you are right: the difficulty of this is higher than simply soldering directly. So no reason to actually try.

Yep, the heat will kill those magnets in a hurry. Plus, after they are soldered to the magnets, what will keep the magnets from moving off target? Before you get the solder to stick to the magnet, a piece of metal like that will get super hot. And the whole corrosion/conductivity angle… Too sketchy… Bite the bullet and get a spot welder. It really is the “right” way to put together a battery pack. Unless you are really a stud at soldering, I would NOT try soldering direct to cell. IMO

Has anyone ever actually had an event related to direct soldering to cells? I mean here, on this forum. I know there’s anecdotal evidence on the tubes but I’m trying to gauge whether I should go for it or spring the $175 for the eBay spot welder…



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I got one of my good cells that i own and my old 80W soldering iron and pushed them together behind a small blast shield and had it sit there for 25 minutes, the worst thing that happened was some of the electrolyte leaked out of the top of the cell. That was at the 5 minute mark. The cell was around 350C at that point and later reached 450C. Never exploded.


Well yes, but it is dead

Obviously. He asked if anyone has had an event related to direct soldering to cells

Nothing dangerous because 18650 cells have a pressure control valve. But you could easily damage your cells and weaken your pack

Scuff surface, plenty of flux, high wattage to get quick joints. Will do very little damage when done properly

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Thanks for the feedback - if my cells ever actually arrive I’m going for it.

Just for fun, I’ll test the capacity of the cell before and after. If there’s a significant difference I’ll post.


@chaka has said you don’t need to scuff the surface since it’s a nickel bond

You don’t need to but it still helps a lot. For a few extra minutes you can save yourself some hassle with soldering

@DougM I was about to solder a 10s4p pack with 18650s and realized as I was getting prepped that it would be 100+ soldered joins to make. I bought the spot welder to save time and to eliminate the risk of damage to the cells.

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why would it be better to scrub? i thought the reason you scrub was to remove oxidation which nickel doesn’t have normally

Agreed I have soldered a 10s4p pack a bit a go and it was a B…

Now I’m working on a 10s8p and I just bout a spot welder because I’m not doing that again especially not double that

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Some cells have a coating of stuff on them i have found, not sure what it is. Also, some cells aren’t actually nickel, so scrubbing is very helpful.

Even if it is nickel and there is no oxide layer, scuffing the surface can still allow for a quicker and easier made joint.

I have soldered hundreds of cells over the past year and i am about to solder a crap ton more and i always scruff them with a light sanding wheel on my dremmel. Takes a few seconds per cell.

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On 10S4P it should be exactly 80 joints - not 100+. Or am I missing something?

Well, you usually do three pairs of joints per cell (2 at a time because there are 2 electrodes) so for 80 batteries you would have about 240 welds.

EDIT: We are talking about soldering so yes around 80 for the cells but then balancing cables. Now we have 91. Volt meters, on off switch ect.

But voltmeter, balancing cables etc. you can’t spot weld anyway - so you would have to solder them no matter what.