Re: House battery system charged by solar & alternator
I have 2 deep cycle house batteries and one engine battery all in the same battery box. I used a constant duty 12V solenoid to connect my engine battery to my house batteries to charge them while under power. I use a switch with an indicator light in my control panel to turn the solenoid on and off . By watching my amp meter when I turn the switch on I can tell if the house batteries are needing a charge or not. If I forget to turn the switch off it's no matter, it automatically goes off when I turn my ignition switch off, a fail safe system. If I wanted to start my engine with my house batteries I just jump the solenoid in the battery box to connect all my batteries together to start the engine (your switch panel in your bus goes dead when you turn your ignition switch to start so you have maximum voltage going to your starter, my battery solenoid won't work when ignition is in start position). With this system there is no way to run my engine battery down with my house batteries yet I can charge them while driving down the road but never worry about whether I forgot to turn the connection off. As stated I put my solenoid in my battery box where I can access it easily. By using regular battery cables and lugs with my solenoid I can connect all batteries together for maximum power no matter what the issue.
You could buy a battery isolator to charge both sets of batteries at the same time from your alternator without any worry of feedback (it's just a couple of diodes in a box) but you would't have the option of coupling them together in case of an emergency.
Including a solar panel into this system may take more thinking but make it fail safe or you will find out your weaknesses at the most inopportune time. On second thought I have talked to my electronics buddy before and he said a solar panel is just a large diode. You can hook it directly to your batteries and not worry about running them down by feeding back to it when the sun isn't shining. I guess you could always put a diode in line to be sure your batteries won't be feeding back to your solar panels no matter what. Of course if you use a charging controller you don't have to worry about it at all. sportyrick