Any interest in DIY battery tab welder?

[RobertB]

Back to the regularly scheduled program

[LightRider]

I always thought they put the slots it the tabs to annoy the person taking them off.

[delete]

@DavidEF

@delete

i have a question.everybody advice me. please.
if i don’t spot welder. but i Place button on top of cell only.Will it works?

and 2nd choice
if i use little magnet place between button and flat cell .Will it works?

1. It will possibly work for low drain applications where there is a strong spring to hold it in place, and the button top never gets any side load (twisting).
2. AFAIK, a magnet won’t do any good, as the button top is non-magnetic material. (I’m likely wrong about this, though.)

Thanks.i wish use with haikelite mt01 or manker mk34/35  
Is magnet can works on that.?

[RobertB]

@delete

@DavidEF

@delete

i have a question.everybody advice me. please.
if i don’t spot welder. but i Place button on top of cell only.Will it works?

and 2nd choice
if i use little magnet place between button and flat cell .Will it works?

1. It will possibly work for low drain applications where there is a strong spring to hold it in place, and the button top never gets any side load (twisting).
2. AFAIK, a magnet won’t do any good, as the button top is non-magnetic material. (I’m likely wrong about this, though.)

Thanks.i wish use with haikelite mt01 or manker mk34/35  
Is magnet can works on that.?

Don’t use magnets on the MK34, or the Haikelite MT01. Magnets ok on MK35

[delete]

@RobertB

@delete

@DavidEF

@delete

i have a question.everybody advice me. please.
if i don’t spot welder. but i Place button on top of cell only.Will it works?

and 2nd choice
if i use little magnet place between button and flat cell .Will it works?

1. It will possibly work for low drain applications where there is a strong spring to hold it in place, and the button top never gets any side load (twisting).
2. AFAIK, a magnet won’t do any good, as the button top is non-magnetic material. (I’m likely wrong about this, though.)

Thanks.i wish use with haikelite mt01 or manker mk34/35  
Is magnet can works on that.?

Don’t use magnets on the MK34, or the Haikelite MT01. Magnets ok on MK35

What the trouble when i use magnet on mk34 or mt01?
I thought,Because the magnet has twist,is right?

[RobertB]

@delete

@RobertB

@delete

@DavidEF

@delete

i have a question.everybody advice me. please.
if i don’t spot welder. but i Place button on top of cell only.Will it works?

and 2nd choice
if i use little magnet place between button and flat cell .Will it works?

1. It will possibly work for low drain applications where there is a strong spring to hold it in place, and the button top never gets any side load (twisting).
2. AFAIK, a magnet won’t do any good, as the button top is non-magnetic material. (I’m likely wrong about this, though.)

Thanks.i wish use with haikelite mt01 or manker mk34/35  
Is magnet can works on that.?

Don’t use magnets on the MK34, or the Haikelite MT01. Magnets ok on MK35

What the trouble when i use magnet on mk34 or mt01?

Look at the 4th picture in this thread. ENEDED

If you had loose magnets on top of those cells, they might dislodge when you screw the light back together, and potentially cause a short. That type of light needs button tops or solder blobs, which is what this thread is about with the DIY spot welder.

[delete]

I think to do this.the flat top inner diameter about 8-9mm. I will use 8mm.magnet put on and lock it by paper insulation gasget(inner diameter 6mm.) and final use shrink tube warp them.
Will it work?

[DavidEF]

@delete

I think to do this.the flat top inner diameter about 8-9mm. I will use 8mm.magnet put on and lock it by paper insulation gasget(inner diameter 6mm.) and final use shrink tube warp them.
Will it work?

If you’re determined to use a magnet, you should at least “tack” the magnet down with some Super Glue (cyanoacrylate) around the edges. Don’t let glue get between the magnet and the battery, since it is non-conductive. If your paper has 6mm hole, I think a 6mm magnet is best. The paper will then also help to hold the magnet from moving side-ways. Then, use the shrink-wrap to hold the paper.

[aarone]

Posting a quick update. Sorry for the delay guys there were several issues with the BOM the circuit designer who created the instructable did and I had to take time to find their errors and correct them. I also let them know of the issue and they’ve corrected the issue on their end as well.

As far as a BOM http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=54cbf7c8a2

It might be cheaper to get the mosfets from an overseas seller on a place like eBay. They’re $18+ through mouser for 8 but I picked up 10 on ebay for $7 shipped. I’m currently waiting on those to come in to test them

Some of the resistors on the BOM are qty 10 because of the price break for 10+, if you need 3 it’s cheaper to get 10

RobertB was nice enough to send me some button tops to test and those do appear to weld ok http://i.imgur.com/Q8Jm5iY.jpg

Two of the welds were a little over done so I turned down the pulse time and got the second 2 on the left.

I’m going to be doing additional testing over the next week or so and then I should have about 7 bare PCB sets if anyone wants one to build themselves.

[DavidEF]

YES! Thanks for the update! :partying_face:

[Lazy-R-us]

This is good news! What were the issues / errors that you found?

[aarone]

@Lazy-R-us

This is good news! What were the issues / errors that you found?

Component count on their BOM was wrong for a resistor leaving you to have one less than the spaces on the board for them.

The BOM from them had the mosfet driver part number as MCP 14E10-E/P. This part number was wrong and when you used that part the board would not function. It had a part name on their BOM of MCP1407-E/P. That MCP1407-E/P was the correct part which makes it work properly.

[RobertB]

Nice work aarone!

[kennybobby]

Can the mcp1407 drive 8 fets—the datasheet calls it a single gate driver.

[Lazy-R-us]

@kennybobby

Is the BOM, quantity 1, correct for that fet gate driver chip? The [old] schematic shows 4 drivers for the 8 fets.

can the mcp1407 drive 8 fets—the datasheet calls it a single gate driver.

i’ll check the new schematic.

I’m pretty sure this is correct, from the Instructable, the list of changes includes this statement:

Update 03.2017
The Spot Welder has a new PCB layout ! Improvements in the V2:

• only one mosfet driver instead of four

[aarone]

correct the one mosfet driver can drive all 8 mosfets without issue… once you use the right one that is

[aarone]

Welp I’m going to suggest no one buys mosfets from china on eBay as they’re fake and self destruct.

Here’s a fake one on the left next to legit ones on the right. http://i.imgur.com/9OftEhR.jpg

Here’s a group of fake China mosfets which grenaded in 1 pulse some in spectacular fashion http://i.imgur.com/fxhgfzr.jpg

I ordered some more legit ones from mouser and waiting for them to come in now. I think the soldered wire connection to the bottom of the mosfet board might be preferable to the bottom aluminum piece. I’m doing some side by side testing once the new genuine mosfets come in.

[Lightbringer]

@aarone

Welp I’m going to suggest no one buys mosfets from china on eBay as they’re fake and self destruct.

I always see them as “Something you might be interested in…” on Amazon, probably used by vapers for vaping mods. I like the cases often used for “box mods”, so that’s how I think I got on that list…

Yeah, I wouldn’t trust those critters for heavy-duty current-handling. Figured at worst they’d just pop and open up. Uhh, electronically, not literally.

At least on Amazon, you can get your bux back, especially with impressive pix like those.

[kennybobby]

Getting FETs to run in parallel successfully can be a tricky proposition. IR has an application note on this subject, AN-941.

Do you know the duration of the pulse, was it auto_connect with the 2 second delay or manual with foot pedal, etc?

Is there anything in the circuit to limit the current to stay within the safe operating region as found in the 1405 datasheet:

[DavidEF]

@kennybobby

Getting FETs to run in parallel successfully can be a tricky proposition. IR has an application note on this subject, AN-941.

Do you know the duration of the pulse, was it auto_connect with the 2 second delay or manual with foot pedal, etc?

Is there anything in the circuit to limit the current to stay within the safe operating region as found in the 1405 datasheet:

I have no clue, so take what I say as it is: coming from an ignorant person…

I would think that for this particular application, the best way to make sure the FETs themselves stay within their safe current limit would be to put more FETs than the power source can ‘feed’. So, if each FET could handle 20A, and the source could supply 200A, don’t just put 10 FETs, but maybe 15 or 20 FETs instead. Let the source itself be the limiting factor. If I were welding, I can imagine I’d want no artificial limits on the output of the welder. But, I’m no welder, so the possibility of my being wrong… :person_facepalming: