What do you use for cell welding?

[WheezyRider]

I bought a Sunko 737 welder, and I used it to build a few packs, but it is not at all safe and reliable.

It relies on a 20A fuse in the 13A plug (with a mains cable probably rated at 10A) and after every 30 or 40 welds, it will blow that 20A fuse. It can also only be used in houses that don't have power trip circuits, because it will cause them to trip after one or two welds.

It overheats after about 100 welds and sometimes it gets so hot, smoke comes out of the transformer in the welder, if the thermal trip fails to shut it down.

Recently I bought a MOSFET/microcontroller based welder for connecting to a car battery, but it failed doing the first weld.

What are other people here using?

 

[wheeliepete]

i'm using a Sunko 709 which works OK and has prob. paid for itself after 4 years and a dozen or so battery packs. If I was to replace it, I would go for the Malectrics Arduino welder which is well supported.

Malectrics - rc and electronics development

Home of the DIY Arduino Battery Spot Welder - You can get prebuilt kits or parts to built your own Spot Welder here.

malectrics.eu

 

[vfr400]

I have a Sunko 788+, which I've used for loads of batteries. The electrode arrangement is a bit wafty. I had to put n insulator between them, and I file my own electrodes out of 3mm copper. The electrodes get hot after a few welds, which you'd expect when welding current goes through thin copper. I have to take a trest after about 10 welds.

Hint: For the best welds, specially in a second layer, cut a slot in the strip to stop the current taking the shortest and easiest path through the strip between the electrodes, or buy slotted strip..

 

[Nealh]

I use the Malelectrics one, even these mini/micro welders one has to be watchful of the heat build up. Though they do have an integrated fan.
The key with these is to buy a quality high 65C rate 4 -5ah lipo.

 

[WheezyRider]

Interesting stuff. Here are some links I found that people might find useful:

Sunkko 788+ Welder failure and repair

I have a Sunkko 788+ Spot Welder. It failed on me rather quickly, either from a faulty triac, or from overheating the triac due to an aggressive duty cycle (I’d say I exceeded the rated duty cycle, but that would imply there was enough documentation to determine this, which… not so much). The...

www.sevarg.net

DIY Arduino Spot Welder

The ATmega328 based Spot Welder MicrocontrollerEarlier when i did mini projects it was hard to solder the 18650 batteries that i had salvaged from old laptops. Not recommended by the manufacturers …

georgehobby.wordpress.com

DIY Spot Welder – Max Weld MOI

The previous version of the spot welder was limited to work only on 230vac. This could be modified to be used with 120 as well by an experienced person but maybe not that easy for the novice users.…

georgehobby.wordpress.com

 

[WheezyRider]

This guy took quite drastic action to get his Sunko 788 working properly:

 

[WheezyRider]

This guy replaced the secondary winding to get his to work properly:

 

[wheeliepete]

There are some clever buggers around, eh! I think there's some threads on ES with people doing Chinese welder mods.

 

[hlensavi]

Thanks for the info, guys!