Load shedding and radio connection?

Load-shedding:

Basically, where a train is say gapped off the juice [the live rails] the unnecessary equipment will begin to shut down, to conserve the batteries.

It may depend stock to stock what equipment will shut down first and in what order, but usually the Air con will go first, then half the main car lights... and so on as the batteries progressively run down...

Not knowing how the 73ts works, I'ts probably a relay to keep the radio 'alive' as priority equipment... Thus something else would have to be switched out...