The old DC board on the website is for the 144v 500amp controller. The new one is here:
https://pandspowerelectronics.ecwid....egory=16287307
It plugs right into 3 IGBT half bridges. I don't have much useful stuff to say about chargers. When I did the charging, I just used several 12v chargers that had isolated outputs so that they could each charge their own 12v battery. You could do that with 24v chargers and it would work fine.