If you are trying to charge a 36 volt DC battery array you need about 42 volts of DC yet you're output specification say that it's putting out 36 volts. Could you explain that at 36 volts you would never charge the batteries.
Should batteries be boiling after being on this UY 900 charger after 20 hours of charging and charger showing 44.2 volts 7.2 amps on the display. Batteries have no load .