The summer of weird and nerdy electronics projects continues… Lately, I’ve been using a lot of 18650 based Li-Ion battery packs in 2, 3, and 4s. As such, I’m thinking I need a battery spot welder. It seems as though a lot of guys prefer the Arduino based DIY kits and I was wondering if anyone had any experience with these. The most popular seems to be from Germany, but there are others… Anyone have any experience with this? If so, I could use some guidance!
American Locomotive
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Seems interesting. I've successfully soldered to 18650 cells before, but it's tricky and you do risk damaging them if you take too long to do it.
theoldwizard1
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I am working on the ultimate, CHEAP design. 12v car battery, wires, relay, push button. V1 did not work well, probably because I was using 12AWG wire.
V2 is almost done. Double up the 12AWG feed wires. The wires from the relay to the "contact" (solid copper nails) are now 8AWG. The biggest problem I have had location the correct size connector (ring terminals).
I'll keep you posted, as it should be complete in the next couple of days.
(That one from Germany is WAY over priced !)
V2 is almost done. Double up the 12AWG feed wires. The wires from the relay to the "contact" (solid copper nails) are now 8AWG. The biggest problem I have had location the correct size connector (ring terminals).
I'll keep you posted, as it should be complete in the next couple of days.
(That one from Germany is WAY over priced !)
OP
I fried an 18650 soldering... hence my hunt for knowledge!
Please do... I think I'm going to power mine with a LiPo just so it's a little more manageable from a size perspective...
theoldwizard1
Well-known member
The kit Ryan is looking at is sold here
As a V3 kit, it is clear the inventor has learned quite a bit. I like the way the it BOLTS to 12V lead acid battery clamps and has a built in fuse (300A is way over kill ! you could probably use a 100A fuse because the length of the pulse is so short). The welding cable set appear to be well made !
Shipping is kind of pricey, but it is coming from EU.
Assembly video
As a V3 kit, it is clear the inventor has learned quite a bit. I like the way the it BOLTS to 12V lead acid battery clamps and has a built in fuse (300A is way over kill ! you could probably use a 100A fuse because the length of the pulse is so short). The welding cable set appear to be well made !
Shipping is kind of pricey, but it is coming from EU.
Assembly video
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todd_fuller
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theoldwizard1
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That is the one that both Ryan and myself mentioned that came from Germany. Around $200-$250 (depending on options and including shipping) with everything.
The Maletrics Arduino kit can be bought "complete" or in "pieces". Many of the "add ons" (foot switch, cables, mega fuse, etc) can be purchased in the US at substantially less cost.
Shipping is €15. Total is about $105US. They accept Visa and Mastercard.
If you are a really an electronics DIYer, the PCB and BOM (bill of material) is available on line. If we had a couple dozen people seriously (as in put up cash upfront) I would be willing to get the PCBs manufactured. You buy the components and assemble.
pcmeiners
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Spent a couple hours going over what systems are out there. I build a welder a few years back from regulator electrolytic capacitors, just before super caps came out, from (10) 200k UF caps, expensive and bulky. Works great but lacks pulse width/multi pulse.
First, I do not like the car battery units, as the volt/capacity can vary which can affect the circuitry negatively. Again bulky, for occasional use it is ok. Another point, seems many of the designers place a fuse and circuitry at a battery terminal, blown fuses and frying wires are not good around lead acid batteries. Main issue is bulk/portability
After reviewing many circuits I am going to hold off buying for a year. I want a circuit which works with super caps, variable power, pulse width and multi pulse. So far I have seen a few circuit board sold with this ability but almost all have multiple versions revisions due to issues ; I do not need issues frying parts. This brings the other issue, support if it goes south, there is little or any from China or India. Preferable I would like a kit designed from state side.
First, I do not like the car battery units, as the volt/capacity can vary which can affect the circuitry negatively. Again bulky, for occasional use it is ok. Another point, seems many of the designers place a fuse and circuitry at a battery terminal, blown fuses and frying wires are not good around lead acid batteries. Main issue is bulk/portability
After reviewing many circuits I am going to hold off buying for a year. I want a circuit which works with super caps, variable power, pulse width and multi pulse. So far I have seen a few circuit board sold with this ability but almost all have multiple versions revisions due to issues ; I do not need issues frying parts. This brings the other issue, support if it goes south, there is little or any from China or India. Preferable I would like a kit designed from state side.
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dtfiori
Active member
I have that exact spot welder and have been using it for the better part of the last year or two. I haven't hooked up to an old car battery and it works great. I build battery packs for electric skateboards and pretty much everything else I need. I highly recommend the Arduino spot welder. It gives perfect welds every time, and I really like the timing feature it has which allows you to not have to use a foot pedal.
Not sure about the arduino version, probably fun but at 109EUR that is crazy...
I have been eyeing on these controllers, minus the welding transformer and what nots chromium copper tips they use.
https://www.ebay.com/itm/110V-Spot-...attery-welder-includ-transformer/283009560494
I have been eyeing on these controllers, minus the welding transformer and what nots chromium copper tips they use.
https://www.ebay.com/itm/110V-Spot-...attery-welder-includ-transformer/283009560494
Rabid Badger
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I'm in the middle of building one from scratch based on the v2.2 Maletrics design.
It'll be handy once it is finished and it has been a good learning experience.
It'll be handy once it is finished and it has been a good learning experience.
pcmeiners
Well-known member
You get what you pay for. You can also weld battery tabs with a single super capacitor, if your lucky.
This looks pretty good
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Haven't bought that unit at all, but I would like to know whats wrong with it... it's supposedly an AC control to the welding transformer like those made from a MOT. It's not a capacitor charging discharging welder. like the one in the Arduino project.
pcmeiners
Well-known member
Not saying you can not weld with this, compare the specs in two kits mentioned by others, specifically current and weld thickness and your support option; the mention of 100 amp scr means little, does not give anything about peak current, the .15mm max gives a hint, none of the info is verified. Using a transformer is an old design. Personally I do not want Chinese support or do I believe what is quoted.
I don't want to derail this thread, but SCR/Thyristors are typical solid state switching controls for AC currents stuff.. 100AMP is just the rating of the SCR/thyristors they selected and used on that controller... nothing to do with the welding current.. If I read that correctly... Other than design is old and you are having some sort of COO bias... what else is wrong with this controller ? Keep in mind that 100A is not the welding current. It's the current pass to the primary of the AC welding transformer... most spot welder probably don't even take that much if anything more than 20A on the primary side.
pcmeiners
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"I don't want to derail this thread, but SCR/Thyristors are typical solid state switching controls for AC currents stuff.."
SCRs control DC
Thyristors , AC
I do not have an issue with the COO....I f you read through many (almost all) descriptions of electronics from Chinese retailers they generally have multiple mistakes due to translation, do you really want to take a chance of the translation being wrong? Also there is no liability if there product does not work.
"Keep in mind that 100A is not the welding current. It's the current pass to the primary of the AC welding transformer."
This not case, the 100a is the current maximum capacity of the steady DC current. Yes the actual welding maximum during millisecond welding could be much higher. The current flowing through the SCR does not flow to a transformer, it is an ON switch for what ever your powering your welder with (battery, caps, power supply). The small transformer powers the circuit on the PCB and other controls only .
Issue with SCRs is once the gate is fired, the feed need to be interrupted to reset the gate, basically you have little control over the power, there is only ON as the gate is fired , thus the use of MOSFETs which allow varying the power and to act as a ON/OFF switch.
On my battery welder I used SCRs, firing banks of 2 capacitors, and I could parallel multiple banks (5 banks) to raise/lower charge from a power supply to control the welds. Workable but primitive. Capacitor bank alone weighs about 20 lbs .
SCRs control DC
Thyristors , AC
I do not have an issue with the COO....I f you read through many (almost all) descriptions of electronics from Chinese retailers they generally have multiple mistakes due to translation, do you really want to take a chance of the translation being wrong? Also there is no liability if there product does not work.
"Keep in mind that 100A is not the welding current. It's the current pass to the primary of the AC welding transformer."
This not case, the 100a is the current maximum capacity of the steady DC current. Yes the actual welding maximum during millisecond welding could be much higher. The current flowing through the SCR does not flow to a transformer, it is an ON switch for what ever your powering your welder with (battery, caps, power supply). The small transformer powers the circuit on the PCB and other controls only .
Issue with SCRs is once the gate is fired, the feed need to be interrupted to reset the gate, basically you have little control over the power, there is only ON as the gate is fired , thus the use of MOSFETs which allow varying the power and to act as a ON/OFF switch.
On my battery welder I used SCRs, firing banks of 2 capacitors, and I could parallel multiple banks (5 banks) to raise/lower charge from a power supply to control the welds. Workable but primitive. Capacitor bank alone weighs about 20 lbs .
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pcmeiners
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Comparison between the Maletrics and Kweld welders.
https://malectrics.eu/
https://www.keenlab.de/index.php/portfolio-item/kweld/
https://endless-sphere.com/forums/viewtopic.php?t=93274
Spent some time looking at the Malectrics and the Kweld welders. Both are excellent welders. Both have support on forums, both are continually being updated hardware and software wise. From many comments I have read, the affordable Asian spot welders are not well liked due to reliability issues.
“In my understanding, KWeld is discharge energy based welder, it does not need 2 pulses and welds will be more consistent, as they do not depend much on contact and time consistency, every weld receives same amount of energy, time is the variable.
Time fixed welds can vary from one to other because of current path inconsistencies, caused by varying pressure on the tab, distance of electrodes, cleanliness of the weld patch, some of those issues are fixed with 2 pulses, where 1st is to clean and clear the path, but there is no guaranty that every weld receives same amount of energy at the end.”
With the KWeld changes to power /time vary due to the weld materials conditions and user interaction, basically changes to resistance during the actual spot weld in real time. The KWeld is slightly better for building multiple large battery arrays in a professional atmosphere.
With the Malectrics, the time and power are manually preset before a welding session. For occasional/light professional use the Malelectrics is still excellent.
There are a few common issues for me with either unit…..
I do not like the enclosures, either kit should be in a larger metal case with a decent size muffin fan. A tiny muffin fan does not cut it
The control knob , screen, inputs should be able to be mounted away from the main PCB as on a front panel of a metal case, all doable but with extra effort.
The 300 amp fuse I find amusing. I understand the reasoning for such a large fuse, as power cable resistance is extremely critical on these welders, the slightest milliohm resistance increase drops the welding current maximum considerably. This also interferes with the cable size limit. Due to the fuse, increasing the cable gauge for higher weld currents has less of an effect then it should, as the resistance of the fuse is the deciding factor, the fuse resistance is a bottleneck. Thicker cables allows lower current loses which allows cooler electrodes, it also allows for longer cables if lower resistance is obtained (no fuse).
With both units, I think the electrode bodies should be thicker to produce less heat and transfer the heat to the cable for cooler operation.
https://malectrics.eu/
https://www.keenlab.de/index.php/portfolio-item/kweld/
https://endless-sphere.com/forums/viewtopic.php?t=93274
Spent some time looking at the Malectrics and the Kweld welders. Both are excellent welders. Both have support on forums, both are continually being updated hardware and software wise. From many comments I have read, the affordable Asian spot welders are not well liked due to reliability issues.
“In my understanding, KWeld is discharge energy based welder, it does not need 2 pulses and welds will be more consistent, as they do not depend much on contact and time consistency, every weld receives same amount of energy, time is the variable.
Time fixed welds can vary from one to other because of current path inconsistencies, caused by varying pressure on the tab, distance of electrodes, cleanliness of the weld patch, some of those issues are fixed with 2 pulses, where 1st is to clean and clear the path, but there is no guaranty that every weld receives same amount of energy at the end.”
With the KWeld changes to power /time vary due to the weld materials conditions and user interaction, basically changes to resistance during the actual spot weld in real time. The KWeld is slightly better for building multiple large battery arrays in a professional atmosphere.
With the Malectrics, the time and power are manually preset before a welding session. For occasional/light professional use the Malelectrics is still excellent.
There are a few common issues for me with either unit…..
I do not like the enclosures, either kit should be in a larger metal case with a decent size muffin fan. A tiny muffin fan does not cut it
The control knob , screen, inputs should be able to be mounted away from the main PCB as on a front panel of a metal case, all doable but with extra effort.
The 300 amp fuse I find amusing. I understand the reasoning for such a large fuse, as power cable resistance is extremely critical on these welders, the slightest milliohm resistance increase drops the welding current maximum considerably. This also interferes with the cable size limit. Due to the fuse, increasing the cable gauge for higher weld currents has less of an effect then it should, as the resistance of the fuse is the deciding factor, the fuse resistance is a bottleneck. Thicker cables allows lower current loses which allows cooler electrodes, it also allows for longer cables if lower resistance is obtained (no fuse).
With both units, I think the electrode bodies should be thicker to produce less heat and transfer the heat to the cable for cooler operation.
theoldwizard1
Well-known member
This is a home brew, DIY, hobby battery welder, or doing maybe a dozen or so cells at a time. The muffin fan was clearly an addon. Better than nothing.pcmeiners said:
So do I ! The multiple MOSFET in parallel, in theory, should be good for more than 300A, but I bet they would blow before the fuse !pcmeiners said:
People need to understand that fuses can go 150% OVER THEIR RATED CURRENT for multiple seconds without blowing. I have watched several dozen inverter/switching power supply repair video. Either the switching diodes or the MOSFETs . Never the fuse.
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pcmeiners
Well-known member
"but I bet they would blow before the fuse !"
Agree
This is a Neanderthal solution. Again the main reason for this fuse size is the lack of resistance. If any smaller, it would severely limit the welding current; why put it in the kit, like you said, it sure as hell will not protect the circuit. The fuse can easily accept >1500 amps for milliseconds while spot welding. Put odds a fire could start before the fuse blows.
"The muffin fan was clearly an addon. Better than nothing."
True.. but what I like about this size fan is they do not make noise, so when they stop working, the circuits over heat without warning. At least with a 3-4" fan, you can hear them in a decent size enclosure.
Anyway I will be spending money on a new battery welder kit in the very near future....this forum gets pretty expensive.
Agree
This is a Neanderthal solution. Again the main reason for this fuse size is the lack of resistance. If any smaller, it would severely limit the welding current; why put it in the kit, like you said, it sure as hell will not protect the circuit. The fuse can easily accept >1500 amps for milliseconds while spot welding. Put odds a fire could start before the fuse blows.
"The muffin fan was clearly an addon. Better than nothing."
True.. but what I like about this size fan is they do not make noise, so when they stop working, the circuits over heat without warning. At least with a 3-4" fan, you can hear them in a decent size enclosure.
Anyway I will be spending money on a new battery welder kit in the very near future....this forum gets pretty expensive.
Rabid Badger
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Rabid Badger
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I based it on the Malectrics v2. 2 design but made a few changes based on how I planned to use it and the parts I had available.
pcmeiners
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Rabid, are you interested in Maxwell 350F ultra caps ?....
https://www.ebay.com/itm/60-Maxwell-Technologies-350F-2-7V-Supercapacitor-Ultracapacitors-6F-160V-EDLC/274379002217?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649
Cheaper for 100F caps...
https://www.ebay.com/itm/MAXWELL-TE...&brand=Maxwell&_trksid=p2060778.c100290.m3507
Plan for the inductance causing a good deal of kickback on the power leads, enough inductance to make the electrode leads jump.
Good luck
https://www.ebay.com/itm/60-Maxwell-Technologies-350F-2-7V-Supercapacitor-Ultracapacitors-6F-160V-EDLC/274379002217?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649
Cheaper for 100F caps...
https://www.ebay.com/itm/MAXWELL-TE...&brand=Maxwell&_trksid=p2060778.c100290.m3507
Plan for the inductance causing a good deal of kickback on the power leads, enough inductance to make the electrode leads jump.
Good luck
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Rabid Badger
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Who isn't interested in ultracapacitors?
My welder is designed to run on a 3-4s lipo battery, but I might have to pick up one of those boards just to have on hand.
pcmeiners
Well-known member
The first link with the 60 caps is a great price if it was not abused, which does not seem likely. It should be sold with flash gear . I bought one yesterday. Figure I could put together a 6S4P setup, and only partially charge the caps for welding....and still have some extra caps.
If you want an insane read.....
http://www.turtlesarehere.com/html/continuied___.html
The last couple chapter goes into issues with the need for TVSS devices, ended up getting a few of each on Ebay
15KPA28A LITTELFUSE
30KPA28A LITTELFUSE
. I bought one yesterday. Figure I could put together a 6S4P setup, and only partially charge the caps for welding....and still have some extra caps. If you want an insane read.....
http://www.turtlesarehere.com/html/continuied___.html
The last couple chapter goes into issues with the need for TVSS devices, ended up getting a few of each on Ebay
15KPA28A LITTELFUSE
30KPA28A LITTELFUSE
Rabid Badger
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The first link with the 60 caps is a great price if it was not abused, which does not seem likely. It should be sold with flash gear
If you want an insane read.....
http://www.turtlesarehere.com/html/continuied___.html
The last couple chapter goes into issues with the need for TVSS devices, ended up getting a few of each on Ebay
15KPA28A LITTELFUSE
30KPA28A LITTELFUSE
I actually added a TVS diode across my input/output bars today. I need another to protect the mosfet gates but I don't have one in my parts bin. Gotta build up the Mouser cart to justify the $8 shipping fee.
pcmeiners
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Yes, I can remember when the shipping fees were just a casual thought, a buck or two.
Now they hurt.
Now they hurt.
Rabid Badger
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Maybe I'll order new mosfets. The salvaged ones I'm using now are good for pulses of up to 300A but they're not really designed for this kind of duty.
theoldwizard1
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This has been my struggle ! I can't find an "elegant" way to connect the 8AWG wire to my copper nails (contacts).
I want to use something like this, but the ones I have bought are either too small (10A rating) or too large (60A rating).
Attachments
Rabid Badger
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Maybe some large **** connectors?
pcmeiners
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Just received the Maxwell caps. They appear unused, figured they still could be 10 years old.... according to the date code they were manufactured in 2019, basically new. They were designed to be used on wind generators. In a 6S4P setup (16.2v @233F) I can use them on a welder or jump a vehicle.
Pretty amazing, the welder I made with electrolytic capacitors weighs about 15 lbs, 2s5p, total (2) Farads. The setup I want will weigh about 5lbs and be roughly 116x stronger .
Pretty amazing, the welder I made with electrolytic capacitors weighs about 15 lbs, 2s5p, total (2) Farads. The setup I want will weigh about 5lbs and be roughly 116x stronger .
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Rabid Badger
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Rabid Badger
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Thanks
I like using that dark plexiglass for my electronics projects. Hit it with an orbital sander and it looks opaque until it's backlit.
I like using that dark plexiglass for my electronics projects. Hit it with an orbital sander and it looks opaque until it's backlit.
pcmeiners
Well-known member
Have not worked on my project a great deal. In the middle of moving out to Penn state. Assembled a slew of parts, and as usually it is costing multiples of my original plan. Using a server 800 watt output power supply, which will supply a 5s5P Maxwell super cap array.
Ended up getting a $100 in Lexan to create the array and house the other components within the aluminum case. Now all I need in a medium size house with a 4 car garage, to get my 12 or so projects going again, hoping for the next couple months.
Ended up getting a $100 in Lexan to create the array and house the other components within the aluminum case. Now all I need in a medium size house with a 4 car garage, to get my 12 or so projects going again, hoping for the next couple months.
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Rabid Badger
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Yeah, DIY electronics is great for learning but not so much for saving money...or time.
pcmeiners
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Definitely not for saving money. As to the time factor, I spend a lot of time in research, part ordering and waiting for parts.... on the other hand I learn a great deal.
