[Myrddin]

The battery busses in a telco central office are carrying -48 volts @ 5000 amps continuous. They are built with laminated aluminum to remain strong enough to deal with the generated magnetic field without twisting out of the support frameworks. The battery racks have lead/acid cells the size of a 30 gallon trash can with the acid open to room air.

The picture above is a lot nicer than what was common when I was a telco central office equipment engineer in the early 80s. The batteries looked like a 30 gallon trash can made of a thick, transparent lucite. It was filled with acid and plates submerged. There were still SxS and #5 crossbar switches mixed with new #1AESS, Northern Telecom digital switches and D4 carrier banks. T1/T1C DSX cross connect panels were new installs at the time.

[lewislynn]

48 v 5,000 a Battery banks connected with zip cord from table lamps?

[eartick]

You did not mention chargers.

Surely this battery system was not powering the 48vdc grid continuously? Life span of these would be nil. Had to have a battery charger from hell to keep them topped off

Of course all the switch gear in the nation (electric grid, pumping stations) use 12vdc charger battery BACKUP system

[Wilhelm Tell]

I’ve been in a few central offices way back in the 1980s. Besides the switches- rows of them - the batteries and also a generator room. I think with the changes in technology there are a lot fewer such central offices.

[Made In The USA]

Great picture! Remember touring a downtown CO as a kid, still remember being dwarfed by rows and rows of switching equipment and clicking from (I think) relays.