Nobster146

That's a good price, where'd you find them at that price?

there's a third resistor in the schematic that is not on the BOM. Any help you can offer?

If they are wired in series then you have a 16.2V 58F capacitor bank. You should be able to use up to a 16.2V charger, but I think most would recommend something more conservative like 14V.

I'm building a battery tab spot welder. Lot's of info out there and people using all sorts of capacitor banks pumping out loads of energy. Consensus says 1farad at the weld is what we want for a good weld. This has to factor in a guesstimate of what the circuitry resistance will be from the capacitor bank to the probes. Amy way to ballpark guess what the loss of farads due to resistance may be? Trying to save money and be efficient in capacitor selection. Do I need to have 58F at the bank to get 1F at the weld or would I be safe with 10F at the bank to get 1F at the weld?

the BOM says use a single 2.7V 350F cap but the instructions say use a 16.2V 50F cap and the pictures clearly show a bank of six 2.7V 50F in series to equal the 16.2V 50F cap. While the single 2.7V 350F is better for space and holds about 100 joules more energy, is 2.7V enough to overcome the resistance it needs to go through to get to the weld?

what would be the reason to not use a power mosfet in place of the IGBT? Cost seems to favor the power mosfet.

thank you. I'm trying to find the most fiscally conservative way to build this. MOSFETs look to be significantly cheaper than the equivalent IGBTs.