Heavy duty spot welding electrodes.

flippy · May 17, 2018

I am starting to build bigger and bigger batteries.
So far i worn out 3 chinese spot welders and currenty running a german one and have one on spare if it does blow up.

My main problem right now is being unable to hold the electrodes due to heating and having to stop to let them cool. I already have fans running to blow air over the battery wich does help a bit.

But in the near future i need to build a 30ish kWh battery. That means building the 3000 cell pack requires double the time as i spend half the time waiting to cool the welder and electrodes.

Are there watercooled electrodes or something? I cannot find anything as google assumes i need to weld a car together.

Ps:i need flexible electrodes. Fixed station is usless due to the small work area of station based welders.

dustNbone · May 17, 2018

Would wrapping the parts that you have to touch with some kind of insulating tape work? I use this fiberglass type stuff to cover hot oil lines, etc that are in places where they might accidentally get touched by bare skin. Something like this:

https://www.texpack.it/product/general-catalogue/texil-en/texil-textape-tape/

Of course the flip side is that by insulating part of the probe, you reduce it's ability to reject heat. But that might not be an issue, as there's several hundred degrees between where you can't touch it and where it's in danger of melting.

flippy · May 17, 2018

i considerd that but it only makes the problem bigger as the electrodes will heat up more and wear out really fast. active cooling is much more effective and better for the hands.

if i cant find anything i will have to construct my own with very thin copper tubing wrapped around it or something.

fechter · May 17, 2018

I made a hand held electrode holder out of some very heavy aluminum. The aluminum would eventually heat up, but there's a lot of surface area there. I used super flexible welding cable. I have never run it long enough to make anything warm.

https://endless-sphere.com/forums/viewtopic.php?f=14&t=89950&p=1336769&hilit=welder#p1336769

You could also try wearing welding gloves and let the electrodes get hot.

spinningmagnets · May 17, 2018

Liquid-cooled electrodes would be simple to design, but a pain to construct. Copper pipe conducts liquid and also current. I've seen a resistance soldering transformer with 2 turns on the output (2,000A?) that was made from copper tubing (with insulation, of course). The two ends were terminated with a "T" fitting. Two legs of the T's had flow from one bucket of water to another (6V), the remaining leg on each had a copper plug that was connected to a cable. It's doable, but...there's gotta be a better way.

An option you might consider, is using very large connectors on the output welding cables, and simply have two sets of cables. Pop on, pop off. I mention large connectors to ensure that those connectors have a solid connection, and they will not get very hot with repeated use. Something like arc-welding 6ga/4ga connectors. The male probe is slightly conical, and after you insert it, you twist it to compress it deeper by a single "interrupted" coarse thread. This is a simple and cheap way to ensure a solid electrical connection on a joint that is frequently cycled on and off...

I have plenty of 7/16th's diameter solid copper rod (almost a half inch rod), in four-inch long lengths. I use them for electrodes, and I can sell you some at the wholesale cost, dirt cheap (no profit to me). I could also drill and tap 1/4-20 threads for set-screws for free if that would help... I also have some 1/4-inch carbon gouging rod you can have for free. You can clamp onto the gouging rod with 1/4-inch copper tubing that has a split on one side, and using tiny automotive fuel-line hose-clamps to compress.

I have an interest in this, because you are spot-welding at a high frequency rate, and I want to see what works best to help alleviate the hot cable and electrode issue...

xxxxxxxxxxxxxxxx

I just checked with onlinemetals.com, the copper rod I use is $8-fiddy/foot, plus tax/shipping/handling, so roughly $12/ft delivered to my door, or $1 per inch.

https://www.onlinemetals.com/merchant.cfm?pid=21965&step=4&showunits=inches&id=1112&top_cat=87

jonyjoe303 · May 17, 2018

what size gauge wire are you using? My advice is to get 6 gauge pure copper welding wire. Its thick and heavy but works great. I had the same problem of overheating probes where I could only do about 20 batteries then had to take a 20 minute break to let the cables cool down.

Using 6 gauge pure copper wire fix my problem. Not only are the probes cooler but I'm able to use a lower power setting to get the same high quality welds. Thats one thing that keeps the probes cool. You can get 10 feet (50 black/50 red) for less then 20 dollars on ebay. Just make sure its pure copper, not that cheap copper clad audio wire. It will fix your problem. Some people use copper nails as there probes. I solder some 10 gauge solid copper wire to the 6 gauge wire, works good. No need to liquid cool just get 6 gauge (at least) wire and lower the power setting.

After getting the 6 gauge wire I was able to tab weld a battery pack with 80 cells without stopping, I could easily have done more, cables got warm but nothing I couldnt handle.

flippy · May 18, 2018

spinningmagnets said:
Liquid-cooled electrodes would be simple to design, but a pain to construct. Copper pipe conducts liquid and also current. I've seen a resistance soldering transformer with 2 turns on the output (2,000A?) that was made from copper tubing (with insulation, of course). The two ends were terminated with a "T" fitting. Two legs of the T's had flow from one bucket of water to another (6V), the remaining leg on each had a copper plug that was connected to a cable. It's doable, but...there's gotta be a better way.

An option you might consider, is using very large connectors on the output welding cables, and simply have two sets of cables. Pop on, pop off. I mention large connectors to ensure that those connectors have a solid connection, and they will not get very hot with repeated use. Something like arc-welding 6ga/4ga connectors. The male probe is slightly conical, and after you insert it, you twist it to compress it deeper by a single "interrupted" coarse thread. This is a simple and cheap way to ensure a solid electrical connection on a joint that is frequently cycled on and off...

I have plenty of 7/16th's diameter solid copper rod (almost a half inch rod), in four-inch long lengths. I use them for electrodes, and I can sell you some at the wholesale cost, dirt cheap (no profit to me). I could also drill and tap 1/4-20 threads for set-screws for free if that would help... I also have some 1/4-inch carbon gouging rod you can have for free. You can clamp onto the gouging rod with 1/4-inch copper tubing that has a split on one side, and using tiny automotive fuel-line hose-clamps to compress.

I have an interest in this, because you are spot-welding at a high frequency rate, and I want to see what works best to help alleviate the hot cable and electrode issue...

xxxxxxxxxxxxxxxx

I just checked with onlinemetals.com, the copper rod I use is $8-fiddy/foot, plus tax/shipping/handling, so roughly $12/ft delivered to my door, or $1 per inch.

https://www.onlinemetals.com/merchant.cfm?pid=21965&step=4&showunits=inches&id=1112&top_cat=87

using water cooling is something i already am considering. there are no electrodes that can you can buy that can do this job in a decent way. it does need to be a split system indeed.
i am thinking about using 15mil copper rod as the handle (as you are already using) and wrap it in 2mm thin copper tubing (and insualtion as a handle). drill a hole and slit in the end and put a (flat) tunsten tip from a welder on the ends. that should last pretty long and not heat up enough to be uncomfortable. copper tips just melt away (litteraly) with constant welding. tungsten is mroe expensive but should last extremely long.

i would love to take you up on your offer, but shipping a few copper rods would be prohibitivly expensive, unless kansas is in china. :mrgreen:

i will order the rods locally and order other assorted crap like pumps on ebay in the coming days and start messing around between building batteries i already have customers for. those take priority over messing around in the shop.
right now i already use 7AWG welding wire. the wire does not get hot, barely warm. but i do want to exend them a bit more (they are 1,5ft now) so i plan to upgrade them to 5AWG and prehaps use a bungee or something on the overhead rack to take up the weight of the cables a bit. the added weight of the water cooling wont help. having to hold more then a pound of copper in each hand is quite a workout.

for reference: most batteries i build are between 200 and 450 cells. or bigger ones made from 200 cell blocks. in a few months i may get a order for a battery (multiple ones if the prototype works out) in the 30~40kWh range. that is 4000 cells for a single battery so efficiency matters ate those numbers. just in welds that is more then 30.000 welds per battery so lifespan is a factor for me.

Heavy duty spot welding electrodes.

flippy

1 MW

dustNbone

10 kW

flippy

1 MW

fechter

Administrator

spinningmagnets

Moderator

jonyjoe303

100 W

flippy

1 MW

Similar threads