Charging 2 Battery Banks with Solar Array

Question:

I am fitting a 50W solar panel to my boat to charge the starter battery and house battery while I am away from the boat. I live in Japan, and the boat is moored 500 miles away so I visit about once every 6 weeks to sail, so I need a trickle charger to keep her topped up. My Marina manager advised me to get a dual solar charge controller, so I can charge both batteries, but very few makers offer a dual MPPT controller. This made me think that maybe most people don't use a dual controller. I'm confused about what to do. Can you advise please. I only intend to run one PV panel. The main draw on my house battery is my Raymarine ST2000 tiller pilot, and I have recently fitted a B&G Triton multifunction system (wind speed, depth, boat speed sensors), so I need to keep both batteries topped up. Can you advise please? Thank you in advance.  - Jeremy

Answer:

Hi Jeremy, a dual output MPPT controller would be the best application to take care of 2 batteries banks with one controller. An alternative would be to install a single output controller to your house batteries and have a directional battery combiner (like Xantrex Echocharge) between house and engine battery. That way the house battery would share a charge from the solar controller to the engine battery. Your solar array needs to be able to get the battery voltage to at least 13.4 or 13.5 VDC to make this combiner to work properly.  - Jeff