Might be that once the batteries are dead the camera does not know how many frames are left, or what ISO I was using so takes no chances and rewinds.
That's not the case .
I've swapped batteries between cameras while I've been out when one set has died .
One camera with colour film in , the other with black and white in .
When fresh batteries are put in the camera it comes back on still on the correct frame number .
The ISO when read of the DX markings remain the same , and if I'm using bulk film , whatever I set it to also remains the same .
If I'm not planning on using a camera for a while , I take the batteries out .
At no time have any of the Minolta cameras done an auto rewind due to batteries dying , being swapped , taken out etc .
Same goes for the Nikon , Canon and Pentax Autofocus SLR's I own .
Only once has a film rewound on me before it should have , and that camera has never done it since .
I reckon the film was either too tight or the central part of the cassette bound and wasn't moving freely .
The camera would have thought I reached the end of the roll and rewound .
Can't remember if it was bought film or a reusable bulk one I fill myself .