I have a problem MOT spot welding

[peleap]

I build MOT spot welding 18650 .It worked well with 0.1-0.12 mm nickel plated but It can not weld nickel plated 0.15 mm thick sheet.Do you have a way to improve performance?To be able to weld sheet thickness 0.15 mm


detail spot welder
- cable welding : copper 35 sqmm
- electrode : copper

[youtube]UK3ahgJyOjE[/youtube]

Please help me
thank you

 

[fechter]

You're doing pretty good welding those to that massive lock. You should try an old battery for practice. The steel in the battery end is way thinner and will heat up much easier than that lock. Try welding two nickel strips to each other without the lock. This will give you a better idea.

What weld time are you using?

How many turns of wire on the MOT?

 

[peleap]

You're doing pretty good welding those to that massive lock. You should try an old battery for practice. The steel in the battery end is way thinner and will heat up much easier than that lock. Try welding two nickel strips to each other without the lock. This will give you a better idea.

What weld time are you using?
How many turns of wire on the MOT?

i use time 60- 80ms

welding turns 3

and Electrode diameter 2 mm

 

[fechter]

That looks pretty good. My guess is you really have enough current to make decent welds on batteries with .15mm nickel or even thicker. Get an old laptop battery and tear the cells out for testing. I've also seen guys use the bottom of an alkaline AA battery, which is fairly close. Make sure you have it dialed in before using on expensive cells.

Slotting the tabs will help also. A lot of work with a Dremel tool. The idea is to minimize current going across the nickel so you get more through it. For .15 nickel, slots are generally not needed. For heavier strips, it really helps.

If you are still not getting enough current, your options would be more turns or heavier wire or anything to reduce the resistance of the weld circuit. With more turns, you have more EMF to overcome resistance in the path. Only so much wire can fit in the core, but I think you want to stuff it as tight as possible. Using thicker weld electrodes might be an easy thing to try. I think the ones I'm using are 5mm and cone down at the tip like a pencil.

 

[peleap]

That looks pretty good. My guess is you really have enough current to make decent welds on batteries with .15mm nickel or even thicker. Get an old laptop battery and tear the cells out for testing. I've also seen guys use the bottom of an alkaline AA battery, which is fairly close. Make sure you have it dialed in before using on expensive cells.

Slotting the tabs will help also. A lot of work with a Dremel tool. The idea is to minimize current going across the nickel so you get more through it. For .15 nickel, slots are generally not needed. For heavier strips, it really helps.

If you are still not getting enough current, your options would be more turns or heavier wire or anything to reduce the resistance of the weld circuit. With more turns, you have more EMF to overcome resistance in the path. Only so much wire can fit in the core, but I think you want to stuff it as tight as possible. Using thicker weld electrodes might be an easy thing to try. I think the ones I'm using are 5mm and cone down at the tip like a pencil.

thank you .I will try as you suggest.

 

[kocetoMR]

Only one transformer is not enaf for 0.15 pure nikel.You must add secont transformer connected in series.You must remove the iron plates between coils

 

[peleap]

Only one transformer is not enaf for 0.15 pure nikel.You must add secont transformer connected in series.You must remove the iron plates between coils

Normally i remove the iron plates between coils .Does the series transformer have to be the same size?

 

[kocetoMR]

Only one transformer is not enaf for 0.15 pure nikel.You must add secont transformer connected in series.You must remove the iron plates between coils

Normally i remove the iron plates between coils .Does the series transformer have to be the same size?

not necessarily.
primary coil in parallel
secondary coil in series

 

[peleap]

Only one transformer is not enaf for 0.15 pure nikel.You must add secont transformer connected in series.You must remove the iron plates between coils

Normally i remove the iron plates between coils .Does the series transformer have to be the same size?

not necessarily.
primary coil in parallel
secondary coil in series

Do you have a schematic for connecting two transformers to me safely?

 

[kocetoMR]

 

[peleap]

thank you
i have transformers 900 watt and 1500 watt. Can i use it ?

 

[fechter]

thank you
i have transformers 900 watt and 1500 watt. Can i use it ?

It should be fine.

 

[kocetoMR]

I recommend you this controller: https://item.taobao.com/item.htm?id=525532538122&_u=t2dmg8j26111
You will get most power then arduino board
Use thicker cable for secondary coil!!!