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  1. #1
    simplecj's Avatar
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    I can spot weld A123 cells!!!

    If you are interested I can probably assemble packs for anyone willing to send me their cells in exchange for a few cells or money. Whatever configuration you need that's not overly huge.

    I'm getting good strength welds and I have PLENTY of material for the connections, all 0.005 stainless clad nickel ribbon.

    Right now my welding platform is still in it's test bed stage... I will be improving on it as I go. I managed to assemble it for only a few hundred dollars, but that was with some thrifty shopping... one particular component I got for about $50 would have cost over $300 new.
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  2. #2
    snellemin's Avatar
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    RE: I can spot weld A123 cells!!!

    That's a pretty cool thrifty setup. Props for your creativity man.[sm=thumbs_up.gif]
    GTP-Pletty Big Maxximum+RX8. GTP-C50-6L Hacker+RX8. CRT.5-C50-Maxx+modded RSpro. TM buggy-1400kv Teknoneu+125B Quark.

  3. #3
    simplecj's Avatar
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    RE: I can spot weld A123 cells!!!

    Thanks!

    I even hooked it up with a Yamaha foot pedal switch to activate the weld. The results are amazing!

    Last semester I drove all the way to Colorado to use some really expensive dual-pulse welder (about $1500 i think, maybe more). The results I got with this simple single pulse welder are every bit as good! And I did it with car audio capacitors! The SCR was the expensive part. I got the biggest one I could find for cheap, 210A to be exact. New ones sell for nearly $300, I got it from a surplus outlet for super cheap and it works like a charm!

    I didn't think it would work, but I figured for only a few hundred dollars it was worth a try. I didn't want to drive all the way to Colorado again, I am so happy!

    I figure if there's anyone out there like me who doesn't access to the right equipment and can't afford to build something like this, I'd be willing to assemble some packs (strapping and welding only) for them to help pay for my setup.

  4. #4

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    RE: I can spot weld A123 cells!!!

    I can see the basic electrical setup here. Just two questions.
    1) Is the driving light there for the light, or as an indicator?
    2) Which side of the computer PSU are you pulling from, the 6V, 12V, or one of the odd ones for the motherboard?
    I have most of that stuff laying around already, and my try one of my own. Thanks.
    P.S. I personally get nervous having work done by someone else, even work on my 1:1 truck at a shop.
    If ya ain't breakin it, ya ain't drivin hard enough.
    Too much power, no such thing.

  5. #5
    simplecj's Avatar
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    RE: I can spot weld A123 cells!!!

    1. The light is for the inline resistance that is needed for the audio capacitors to charge from a discharged state. They include a resister with the caps, but i thought the light was cooler.

    2. I actually ended up using a 6-15v Pyramid bench @ 15V. Caps would pull about 5 amps tops (I think the headlamp acted as a current limiter). I powered the SCR from the same source. I also think a slightly higher voltage, maybe around 16-20v would do a bit better, but the car audio caps yelled at me for exceeding 16v, so the 15v PSU was perfect.

    I actually had to give one of the caps back to my buddy who let me borrow it. I didn't get very good welds on the positive terminal until I hooked all four caps up for a total of 21F. I think the caps are over rated though, higher quality ones might do the job with less.

    I also successfully soldered several cells that had lost the thin nickle plat on the positive terminal. It kind of sucked though and took a 260W iron (my 140W didn't cut it) and a combination of zinc solder and flux on the aluminum cell and lead solder on the tab; heated and dropped together.
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  6. #6

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    RE: I can spot weld A123 cells!!!

    Very nice packs there. I could certainly use a tool like that around the shop. What are these packs going in?

    - David

  7. #7
    simplecj's Avatar
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    RE: I can spot weld A123 cells!!!

    They're going in my electric trike (already got 37+ miles on them). I've got a thread on Endless Sphere about it.. follow the link. Check out my removable trunk with ventilated battery boxes!

    My electric trike thread on Endless Sphere

  8. #8

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    RE: I can spot weld A123 cells!!!

    I'd sure like to see a HOW-TO write up on your micro spot welder build. It seems much better suited for battery spot welding than the crude MOT based instructables posted out there?

    Any interest in collaborating on a write-up?
    Jim

  9. #9

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    RE: I can spot weld A123 cells!!!

    have you tried using a car battery instead of capacitors ?
    I have heard many stories of people welding with car batteries

  10. #10
    simplecj's Avatar
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    RE: I can spot weld A123 cells!!!

    Basic components...

    * Benchtop power supply @15-16v (amps depend on cap charging rates... mine used about 5A max using a foglight for the charging control resistance)
    * SCR (Thyristor) 220v/220a Single or Dual channels. You only need one unless you want to add a second set of capacitors and a reed switch for dual-pulse welding, but that's much more expensive I got a used dual channel one from an ebay surplus store for about $40, would have cost hundreds to buy one new
    * Charge controlling resistance - not sure how to calculate for different cap set-ups, but mine ran as stated above using an automotive foglight @ about 5A max for ~40 second charges
    * Foot peddle ON/off to activate SCR switch and weld (I used the same 15v power source for the switch, which is fine with such a heavy duty SCR.)
    * Heavy 2gage braided copper car audio wiring between main cap lead, SCR and contact points
    * Thick solid copper grounding wire, clamped to braided wires and filed to a point at the ends (you can fix these however you want, just make sure your hand isn't going to be in danger of becoming part of the circuit!
    * ~21+ Farads total capacity - I used: one 10F, two 5F, and one 1F car audio capacitors all wired in parallel with 6g wire. You can find these cheap on ebay.


    How you wire it up is up to you, this is just a rough list of what I used. Keep in mind there are many factors that will effect the quality of your weld.

    * Clean all welding surfaces with a non-residue cleaner like high % alcohol. You want to optimize the metal to metal contact, so it must be free of oils and debri
    * Keep the welding tips clean by regularly filing them to a rounded point. The size of this point will effect your weld, too large of a point won't weld fully, too small and it will likely blow the tip off before it welds the material.
    * Play with voltage and capacity, using my values as a baseline. I had a feeling that if I went to a bit higher voltage I might have gotten better welds, but the circuitry of the audio capacitors limits it to about 16v and sets off the alarm (my PSU maxed at 15.5v anyways). The caps are rated to 24v, so if you could bypass the control circuit you could easily try out the 16-18v range if your PSU can do it.
    * Make sure you apply adequate pressure to both contact points and that you are only welding within the center button area. A strike to the outer edge of the positive terminal can easily rupture the cell. It's not particularly dangerous, but fluids will leak out. I managed to seal a couple that I ruptured during wiring, by accidental arc across cells, with JBweld, only apparent affect on the cell was a minor reduction in capacity. According to the California Materials spec sheet for A123 cells, they do not contain any toxic or hazardous chemicals.
    * Always wear eye protection, you'll be throwing sparks in your face for hours!
    * Ventilation is recommended

    Here's the site that gave me the idea in the first place... however they hadn't been successful with A123's with their setup.
    Here is the basic wiring diagram:


    EDIT: More recently I was able to repair my RC packs using only 16F, you just have to make sure everything is flat and clean so you get good conduction.

    If you'd like to give the dual-pulse welder... here's some more info (click go there)


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