If you back in history you will find that a BAC 111 or Viscount, I'm not sure which, suffered a total gen failure in IMC at night in the UK some 20 odd years ago, perhaps longer...I'm scratching the memory bank here!...
They ended up on battery power only, lost that on descent still IMC, and ploughed into the ground from about 15 grand inverted, I think!
It was a freighter. The details will be in the archives somewhere.