I really do not know much about this make. My understanding is that it is a quartz movement
Can you describe the box and perhaps post some pictures?
I have a Glasshutte Marine Chronometer that uses two batteries, but is happy to run on one. That gives it, effectively, maintaining power because you may leave one battery in place while changing the other one and then replace the second one without ever losing power. Mine has been tracking standard time to within one or two seconds for a couple of years now.