AMP Draw Issues

I know it is tough to avoid taking the battery below 50% charge and damaging it. I did it on our first lengthy trip. We drove every day, engine charging took the batteries' voltage up over 13 volts and it stayed there until we went to bed. We didn't use the furnace during the night (April in southern British Columbia) so the first clue of my lack of understanding was the furnace not working in the morning. It soon got worse so hours of driving didn't allow any evening heating. My basic problem was too little charging (engine charging isn't very effective) and not realizing the voltage chart is overly optimistic for hours after charging. New batteries and much less use got us home fairly comfortably. We never plugged in to shore power and I now know that our old converter is pretty much useless anyway, only "charging" at 13.6 volts.

I worked hard to improve engine charging, getting rid of voltage drops in the connectors of the wire from engine to house batteries, eliminating the battery cutoff switch and its wires. LED lights reduced the power draw (fridge, lights and furnace being our only loads). That was better but I was always wondering what the state of charge was. A cheap eBay battery monitor indicating the per cent of charge all the time helped a lot. But it became obvious we needed to give up boondocking, use a generator or solar panels. We chose solar and it turned out just a 100 watt panel solved the problem completely for us doing only summer camping with modest power needs.