ive been looking for a battery spot welder for 18650 batterys ive fix a few batterys using soldering but ive sold a few items from my tool kit and some money is there and if i dont buy one they money will just be spent on paying a bill or sutch so got to buy one

but what one as im not using it that much im torn on chargable ones the small pen ones seam to have a bit hit and miss reviews the ones that run off a car battery seam ok but means i have to keep a large car battery lying around for that now and again use there are ones that just plug in to 240v that seam to me to more ideal but a lot more in the price range so i have to justify the spending and would be top of my buget

Can't you use a decent bench PSU instead of a car battery?

The Fnirsi portable battery spot welder seems to rate well on reviews. Short leads are the main gripe. I'll see if I can dig out a link.

Link:

A few large capacitors and a car battery will do the job.

Can't you use a decent bench PSU instead of a car battery?

I do have a bench supply but I was thinking if getting rid of it sat in a drawer taking up room ive only used it once does 30v but would it out put the amps over such a quick time im thinking not

Link:

Will have a look at reviews on that thanks

A few large capacitors and a car battery will do the job.

Thinking on something small easy to store rather than that large

I have one that uses a car battery and it's quite good. You can also use some of them off radio control power packs which would be more compact.

@JOEPRO bought one recently that was compact and worked well.

A bench power supply will not work because you need a sudden dump of a lot of amps to spot weld. If you added some large capacitors into the circuit it could work.

It will depend too on how many welds you need to do. A small supply battery will quickly get exhausted but maybe ok for a few welds.
I can assemble a 5s2p battery no bother using a car battery, that's 52 welds. I usually have to pause a few times because the electrodes get too hot to hold! When I'm finished the battery can be stored away leaving the bench clear.

https://www.ebay.co.uk/itm/25476822...attery+spot+welder&sacat=0&relatedSearch=true

This is the one I started out with. I carried out the common upgrades to the circuitry and it served its purpose well for a few years but I always had to have it set to 99, full whack to get a decent weld.
But recently it started producing poor penetration welds. I suspect one or more of the mofsets has failed.

I got on the battery forums and this one seemed popular.

https://a.aliexpress.com/_EJ0pqAw

It's an improved design with more mosfets. I've practiced with it and it is a lot more powerful than the original, doing decent welds at half power.
Only downside is that there is no facility for a foot button control. When you touch down the electrodes it automatically sends power.
On the old one you were able to make sure the electrodes were in the correct place before using the foot button to switch on the power.

I should talk about the nickel strip you use to weld the battery.
Nickel plated steel strip welds better but conducts badly compared to pure nickel.
With the same welder you can weld thicker plated strip so you have a stronger assembly but compromised power output.
I only use pure nickel strip but my old welder would only do 0.15mm max thickness. I think this new one will do 0.2
Most decent brand batteries use 0.15 to 0.2mm pure nickel strip.

Be careful where you buy the strip because there are a lot of cowboys selling plated stuff as pure nickel.

I always use this seller.
https://www.ebay.co.uk/itm/193857900011

His stuff is genuine pure nickel.

Here's a very simple car battery version. The pushbutton which triggers the car starter solenoid could be replaced by a floor switch. I think you would need a better handle to hold the electrodes. Adding a capacitor bank ( e.g. 100,000uF at 25v ) would be an interesting experiment, and might allow the 12v lead-acid battery to be replaced with a small 12v lithium power tool battery.....

Here's a very simple car battery version. The pushbutton which triggers the car starter solenoid could be replaced by a floor switch. I think you would need a better handle to hold the electrodes. Adding a capacitor bank ( e.g. 100,000uF at 25v ) would be an interesting experiment, and might allow the 12v lead-acid battery to be replaced with a small 12v lithium power tool battery.....

Simple Battery Spot Welder

Simple Battery Spot Welder: As part of an electric bike project I needed to weld 70 18650 Li-Ion cells together. I could have just bought a battery welder but where's the fun in that? This is my build. Nothing complicated and it didn't need to last too long.

www.instructables.com

Unless you already have the materials it is going to cost more than the one I linked to for less than £20. And with it you have acurate control of the power you are applying.