So, did you or did you not discuss this with your instructor?
Actually, sounds like you did NOT read the FCOM, because if you did, you'd know that:
1. Cargo smoke indication is on DC Bus 2;
2. Said DC Bus 2 is not powered on Battery Power only with speed below 50kts;
3. Cargo fire extinguishing is on DC Bat Bus;
4. Said DC Bat Bus IS powered in that scenario.
Ergo, on Bat only you don't have cargo fire indication, but you do have extinguishing capability.
You're welcome. Next time actually read the book, don't just say you read it.
Last edited by Amadis of Gaul; 14th Jun 2017 at 13:23.