Well this Trimax unit has outlasted 2 modern switchmode chargers and once I had sorted the effects of my very poor storage for 10 years its back up and running happily.

NO fan cooling and generally quite quiet after I jammed a piece of broomstick in between the RHS of the case and the edge of the choke which was humming like bee and varied wildly according to output.
Dunno how they got their fingers in there to bolt components in place but I could not get at the choke mounting bolts to remove it and tighten up the core bolts to shut it up without removing heaps of other stuff. So I took an easy option.

It is controlled by a Victron SOC meter which kicks in when the SOC of the Lithium bank gets to 30% SOC and charges flat out 20 odd amps until the SOC gets back to 50% & then stops. Is worked quite hard and then given a bit of a rest and usually only during winter when the solar O/P is way lower than what I see in summer.

There must have been thousands of these things made by Trimax for PMG/Telecom as almost every place I worked at had similar units working but in widely varying ranges of ouputs.
However once they got over 50A they tended to use servo driven variacs to control the output as we found that BIG SCR fired chargers would drive the standby gen sets nuts with the sudden inrush currents.
The Serial No on this one is 530 and was removed from service about 1988 and I acquired it 2 years later when the building it was installed in was about to be demolished and nobody wanted the gear and a mate of mine wanted the relays in this PABX for his model train work so I helped him clear the room and for that I got the batteries and all the power gear associated with it.