Soldering batteries using tab wire

[fixit7]

I was thinking of replacing the 18650s in my Dewalt battery when they go bad.

When using tab wire, what temp do I set my iron for?
The iron is a Hakko wanna be.

My iron goes up to 450C if I am reading the dial correctly. (It had no manual.

I read that you should go hot and fast to avoid ruining the battery.

 

[audioguru]

Are you using 18650 lithium battery cells that have solder tabs welded on each end? My soldering iron has a fixed temperature of 370 degrees C for all soldering that takes only one second. Maybe your soldering iron has a light dimmer circuit for variable power without controlled temperature.

You do not want to cause a lithium battery to explode by soldering directly to the ends of it that has no solder tabs. Years ago Ni-Cad batteries were soldered directly to the ends because Ni-Cad does not burn like Lithium does.

 

[fixit7]

I will find some with solder tabs.

 

[Nigel Goodwin]

I will find some with solder tabs.

AG is scaremongering as usual, Li-Ion batteries solder quite easily, clean them first with abrasive paper, and solder them as quickly as you can. We use leaded solder (lead-free solder is useless stuff!), with an iron set to 325 degrees C - I presume AG's is for lead-free, as it's rather hot for leaded.

Mostly though now, we spot weld nickel strips to the cells.

 

[fixit7]

 

[Nigel Goodwin]

Like I said, they are easy to solder.

 

[audioguru]

In Google, there are articles explaining the damage that soldering can cause to a Lithium battery and people are saying to use gloves and eye protection in case the battery cell explodes. That is why manufactures safely use spot welding.

 

[fixit7]

Another reason is probably cuz it is much faster.

 

[Nigel Goodwin]

Another reason is probably cuz it is much faster.

That would be the main reason - and why we do it.

 

[audioguru]

I have never seen nor heard spot welding to a battery cell. Is it fast enough to make a POP sound? If so then obviously there is no thermal damage to the inside plastic insulators of the cell.

 

[Nigel Goodwin]

I have never seen nor heard spot welding to a battery cell. Is it fast enough to make a POP sound? If so then obviously there is no thermal damage to the inside plastic insulators of the cell.

It's how battery packs are made, this is the type of machine we have:

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For those who might like to make one? - you can buy a number of different cheap electronic control modules and make your own using a microwave oven transformer:

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[fixit7]

I may consider making one. How would you hook the circuit up to the oven transformer?

The videos I saw, showed them cutting the transformer up and using 4 gauge wire.

 

[audioguru]

All the 18650 cells I have salvaged from laptop batteries are spot welded together with metal strips. I simply solder to the metal strips. When I use a cell with a strip welded on it then it is easy to rip off the strip to use the cell in a cell holder.

 

[Nigel Goodwin]

I may consider making one. How would you hook the circuit up to the oven transformer?

The videos I saw, showed them cutting the transformer up and using 4 gauge wire.

If you google there are numerous examples out there, usually rewinding the secondary with VERY thick wire.