This week getting more done on the spot welder has been my goal. There is a lot of details. I got more parts from Halted. The fet board in now tested and fully modified and assembled. I’ve gutted the chassis that the spot welder will be mounted into. It’s going to be a very tight fit. I’ve cut a base plate to mount the electronics onto.

Here is the modification that Fritz has everyone do to their boards. We are suppose to just use a piece of solid wire down each open path. I used copper plate to make it even more robust.

To help keep warmer parts cooler, they get mounted up off of the pcb.

With my experience with motor controllers, it seemed prudent to add a schottky diode and 10 ohm resistor to each fet’s gate pin. There is an issue with ringing on the fets. We are suppose to add a board full of schottky diodes to lower the ringing’s peak value to less than the voltage rating of the fet’s diodes. I used a pointed spiral bit for cut across each gate’s trace. The gap is just wide enough so that an 0805 sized resistor can fit across it. I used a 1/8″ endmill to remove the green solder mask to make solder pads for the new components. A very light touch was required to remove the solder mask without removing any copper. I used my Bridgeport mill for this mod.

Here the parts are mounted next onto the gate’s trace. A perfect fit on the width of the trace.

Here is 1 of 3 heatsinks with fets mounted, ready for pcb installation.

Here they are with the heatsinks mounted. The one row of parts on the right, just clears the heatsink due to the double sided foam tape thickness. I still had to space the heatsink up off of the pcb a little more so that it did not contact the delicate glass diodes. The other two rows of parts were totally clear of the heatsinks.

I found on the Endless Sphere forum a BMS that matches my needs and philosophy of being simple, but with a processor. Here is the link. He talks about his design as he builds it in other threads. I just don’t see anything since late 2009 on the progress of the design. I’ve emailed him. We’ll see.

Here you can see his prototype layed out. It communicates using infrared leds. That helps get around the EMI issue.

Tonight I finally got this system debugged. Turns out it had a bad transformer on phase A. Runs smooth as glass now. I left it outside since it’s so cold here now. This will cold soak the Dolphin and help to test if it’s prone to classic dropouts or not. Cold and humid weather pushes any marginal board right into classic dropout mode. Clunk clunk!

Got another customers board today from Hawaii. It needs the dropout mod and also I’ve been requested to add the 70kw upgrade. Busy weekend.

I have have gathered up all of my individual schematics of the Dolphin system and am drawing them up to make a master schematic.

Since I’ve been hammering away at debugging this east coast system, I built up another system to help me. So now I have another completely assembled system that runs.

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