A123 UPDATE

These welders have many variables and depending on the size cables, probes and capacitors you used etc. will determine your weld settings. I have done hundreds of welds on A123 batteries and determined that they are no different from any other batteries. When your tabs are too thick to make decent welds, you have to improvise. Current always takes the easiest path and by making dimples and a cut in the middle (picture below) on the tab you are welding will force the current into one dimple, through the battery and out the other dimple. Concentrating the heat on the dimples and produce very strong welds.

You can punch your own dimples and use two pieces of nickel like the picture below.

 The probes are also very important, don't use probes with  flat tips unless you have a weld head that pushes the probes perfectly flat on the piece that gets welded. Make your tips round on a lathe with a file, like the microscope pictures of my probes below and then use very fine sanding paper to smooth the tips. Rounded tips will make perfect welds every time, won't stick and you can hold the probes at almost any angle.

PULSE ARC WELDING

I'm looking into adding pulse arc welding to this welder. Pulse arc welding is like TIG welding. By adding Argon gas through a special gun with a tungsten tip will produce a very hot plasma arc that will melt almost any metals together( including aluminum, gold and silver).  This welder was originally designed to use a contactor and  can easily be converted to activate an argon gas solenoid and a retractable tungsten tip. I will appreciate any input. 

ESR TEST AND A123 CELLS

I have measured the ESR of my welder and its much lower than anticipated. The ESR of the welder bus bars at the front of the welder measures less than 0.0005 Ohm (500 micro Ohm). With such low resistance, this welder can produce astronomical currents and will only be limited by the resistance of the probe, wire and material being welded.
I am way behind schedule with my version 3 processor and spent most of my time getting the new welder built.

 Most companies and people out there that are welding A123's are very tight lipped about how they do it and I would like to get to the bottom of it!!! I'm  doing some experiments with inverted resistance welding and was wondering if there are some of you guys that would send me some of your old A123's to play with ??? I will post all my findings on here!!!

NEW WELDER

I started my new welder up today and did a couple of test welds. The welds look really good and much better than my previous welder.  I welded some copper to a washer at very low voltages and also checked to see how fine the settings can go by welding  80 micron gold plated tungsten wire to a washer (the photo below was taken with my microscope) and I placed a small BC 847 surface mount transistor next to it. My probe tips are all messed up and I am busy cutting new ones with my lathe which will make much better looking welds. I will also test the ESR this weekend and I'm hoping that it will be in the 0.001 to 0.0015 Ohm range.

WELD POLARITY

I have many guys asking me why their welders  burn  holes every now and then and what the big deal is about the polarity of the probes.

Resistance = heat, meaning that the higher your resistance, the more heat you will have. Probe pressure is very important and the harder you push on the probes the better it will make contact and the lower your resistance will be, causing welds that are  colder and with too much pressure too cold to melt the metals together. If the probe pressures are not firm enough, it will cause a higher resistance causing too much heat and burn holes. That is why many companies that sells these welders have Weld Heads that are adjustable and make  welds when a settable pressure is achieved.  That does not mean that we cannot make any good welds by holding the probes in our hands.

Polarities are also very important. when a weld is made it forms a nugget  between the metals being welded. This nugget is the melted metal between the two metals that joins them together and you want this nugget to be in the middle of the metals being welded.

When you do a weld the nugget gets attracted to the positive electrode more than the negative electrode and also gets attracted to the metal with the higher resistance. When you weld copper and steel together the nugget will form in the steel with the higher resistance and little or nothing will form in the copper making the copper not stick to the steel or a  very weak weld.

A way to move the nugget to the middle of your weld  is to always put your  positive electrode on the material with the lowest resistance, like copper and your negative electrode on the steel with the higher resistance. If you weld thick and thin metals together you will have to put your positive electrode on the thicker material(thick metals take longer to melt) and your negative on the thinner material.

 By looking at the photo below, we can clearly see the electrode positions.

The welds at the bottom of the "stock welds" and " My welds"(I got this pic from a guy that bought one of my boards) are deeper than the top ones and kind of went through the metal, making them weak welds. The positive electrodes were at the bottom of these welds and the negative electrodes were at the top. To overcome the deep welds at the bottom you have to put more pressure on the bottom probes (making  colder welds) and put less pressure on the top probes (more resistance = more heat which will make deeper welds).

NEW CASE

                  THE 4 SCREW HOLDING THE LCD WAS WELDED WITH MY CD WELDER

                                                  CNC CUT OUTS ON MY NEW CASE

UPDATE

I was promised a case for my welder but it seems like I'm not going to get it after a  5 month wait. I decided to buy the 12 X 12 X 19 case from mouser ($140 including shipping and taxes) HERE. This case is bigger than what I need but I guess it will do for now. I'm going to cut out the face with my CNC milling machine this weekend and rebuild all the circuitry into the new box.
I did some tests on my welder to determine the ESR and Max weld current. I connected 3 X 1 Farad computer grade capacitors with #8 welding cable and got an ESR of 0.0020mOhms. At 20V you will get 10 000 amps. The Mosfet board can  handle 15 000 Amps and by using bigger cable, copper bus bars and better connections can increase the current to give you much better and deeper welds than Sunstone Engineering can ever give you for $8000

New Version3 MicroProcessor

I have been working very hard on a Version 3 Microprocessor for this welder. Version 3 will change this welder from timed pulses to energy pulses. Energy pulses will give you more control of your weld by calculating and  adjusting the pulse width automatically to the resistance that you are welding, preventing burned holes due to the wrong probe pressure and a change of resistance. This processor will also have features showing the capacitance of your capacitor and a feature to change the max voltage  to 24V.

ORDERING MOSFET PCB's

I placed an order for more Mosfet PCB's and I should receive it by  4/12/10.

MOSFET PCB's ON ORDER

I've checked  the board for fabrication errors and the only small problem that I could find was that the holes for P1 and P2 are a little small. The terminals still go in with a hard push though and it should not be a problem.
If you look at the board it is hard to believe that it is 3oz copper but by running your fingers over the edges of the copper you can feel the the difference. The board is also heavier. The camera and lights make the silver color on this board look like it is copper.

Mosfet PCB's shipped

The Mosfet PCB's are on their way to me and should arrive Friday.