SimonSolar2C

We just got ourselves a 1993 Toyota Hilux Galaxy Fibreglass motorhome with just 46,000km. The person that sold it to us installed a 190watt solar panel with a Steca MPPT charge controller which they connected to the new 80AH leisure battery. I added another 100AHDeep Cycle battery in parallel. Here's the problem - I'm running a little Electrolux 3 way fridge on the 12v system. (The AC and gas don't work) It draws about 7amps. So the solar panel won't be enough to run the fridge and lights 24/7. Therefore I need to run the engine as well to charge up the battery. For some reason, the battery doesn't seem to charge much off the alternator. My theory is that the solar panel lifts the battery voltage about 1 volt even at its comparatively low current, and the alternator sees that as a fully charged battery and doesn't send it any power. Or at least doesn't top the battery up. The result is the fridge only runs for about two hours after sundown, until the MPPT regulator disconnects it (at 10.5v?). Assuming it's all hooked up correctly, is there a solution to this problem? Or maybe there is an isolator with two inputs, one for solar and one for alternator? Or do I need to disconnect the solar panel when running the engine? Picture of the existing isolator and a little thing between it and the leisure battery. Maybe that's a self resetting fuse.