Good success today!
I replaced the bottom resistor in the picture above in my previous post so I can push the voltage to 63V. I pushed up to 62.5V, and left it running for 20 minutes and nothing got very hot.
I did not have a 2.7k resistor so I soldered 2x1.3k resistors in series, and made a little arch above the 0603 pad

I took some readings, while adjusting the pot 100mV each time. The results are pretty great - very linear curve of potentiometer voltage vs output voltage. An R^2 of 0.9994!!!!
After scanning the range of the output, I got one of those spools of plastic coated steel wire (used for gardening) in a bucket of water as a loadbank. I only ran a 12A load for 5 minutes before the plastic started to make smoke bubbles... the wire was wound too close together and could not be cooled with the water!
Also I'm in an apartment so I can't get easy access to 230Vac (I would have to pull out the oven) so I used my homebrew re-wound microwave oven transformer for testing purposes.
My next step is to have a larger load (45A?) and run the power supply at 62V for many hours... I want to make sure the power supply does not explode/overheat. I'll probably borrow a Flir camera for this test. Not many charging stations can supply that amount of kW so it's overkill, but I like testing in more extreme conditions then it will see in use.
SpmP said:
I think we need a wiki page for these beasties, or are they a bit of a _has-been_ thing?
Nice Idea! I'd be game for contributing to a wiki page although I'm not sure how to make one. There is a wiki page which links to this thread lol.
https://endless-sphere.com/w/index.php/Chargers_LiIon_Bulk_Chargers_HP_Server