Have you checked the voltage on the secondary battery when the fridge turns off or before you take it for a drive to see what it is getting down to?
Not knowing how you’ve set up your fridge connection, I’d be leaning towards insufficient gauge wiring and earth connection which has been highlighted with an alternator possibly on the way out.
I ran 6 gauge positive and negative from the battery to the boot dedicated for the fridge, and that has always worked well. My battery is getting close to 4 years old now, so maybe due for replacement soon as well
Sent from my iPhone using Tapatalk
Reply With Quote