Somewhere else here within the RH Forum, the consequences are discussed of a total electrical failure in case of a Robinson piston product (
Hypothetical - Robinson Total Electrical Failure). As Robbie pilots know, if after an alternator failure one continues to fly until the battery is flat, the donkey would continue to run, but one would lose all electrically driven instruments incl the RRPM tach.
However, if for example in case of an electrical fire one elected to switch off both ALT and Master, the tach's would still be energised via a special circuit straight from the battery.
How does this work in a Cabri?