What you have is a transformer that have several windings;
see and read the message :
- Re: Interesting Discovery
The same or equivalent unit that had an output set for the 36 volts battery supply.
Still, I asked what other parts You got and you have not replied with an answer.
You may have big diodes rectifiers, and for sure large capacitors for the resonant section of the regulating transformer.
36 Volts at 30 amps capability as you read the info.
The charger was based in a regulated 46 volts to give a 56 volts charging voltage that when charged a relay may have tripped to disconnect the input power, no need to disconnect anything else.
One simple way is to use two rectifiers and two SCRs to charge the battery bank up to and including bulk charging then drop to Float charge.
Are You SURE that is a half way rectifier ?.
Normally, full way rectification would have been for the charger the best arrangement, specially for a Resonant regulated transformer.
A small circuit to trigger the SCRs to regulate the output voltage and current.
Are you going to charge 36 or 48 volts battery bank ?.
If 48 volts ( 56 volts peak) then You need to make some measurements.
Nando