Salut Christiaan -
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That "strange voltage" 112V DC was used in the DH Comet and SE Caravelle.
I have no operational experience with these types, but I did fly them a few times (just providing my body as co-pilot for ferry flights) long ago... in the 1970s. The 112V DC requirements was a nightmare for ground handlers.
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The RR Avon engines fitted on the Comet and Caravelle had 112V DC electric starters. Both types had a large bank of multiple lead-acid 28V DC batteries in the belly, and the F/E had a selector for "Start 112V DC" or "Normal 28V DC"...
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The batteries were switched by this selector to be connected in "series" to obtain 112V DC, for start purpose, then after engine start, the selector was moved back to normal (or parallel) to supply the aircraft 28V DC for most of the electrical requirements, and into inverters to produce 112V AC for various avionics.
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United Airlines operated 20 SE210-6Rs in the USA, and while at their stations they had a ground transformer/rectifier to change the regular 115V AC ground power units, these airplanes often carried a portable unit when flying to other destinations.
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I had old manuals from Comet 4C (Argentina) and Caravelle (United) but they probably ended in trash somewhere, so I can only inform you with what I remember from them.
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I ferried a Comet 4C from ABQ to ORD (ex Mexicana) as F/O around 1975, and the battery bay showed a lot of corrosion (due to the lead-acid batteries). I think the FAA had approved to install big truck 28V DC batteries, for the ferry flight, as the aircraft batteries were dead and beyond their useful life. Other than rather "non standard", both Caravelles and Comets were very nice planes to fly.
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They had 4 hydraulic systems - two were engine driven pumps, two were driven by 28V DC pumps - for gear, brakes and flight controls - I think they were named "red", "blue", "green" and "yellow"... Funny is, in case hydraulic system reservoirs were running dry, the AOM mentioned that "coffee or strained tea could be used in case of emergency"... makes me laugh (and milk was NOT recommended) - I actually quote the Hawker Siddeley Comet 4C manual.
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Oh, après tout, ma petite MGA "Twin Cam" '58 (ma première auto) avait 2 batteries 6 volts, connectées en série pour produire les 12 volts.
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Happy contrails