atreis wrote:
My AGM batteries usually read 13.7 volts. When I turn something on they'll drop pretty quickly to 12.8-12.9 and decrease very gradually from there.
If yours drops to 12.1 as soon as you turn the furnace on, either there's a large voltage drop for some reason (wire too small) or the batteries have a lot of internal resistance (they're nearly shot).
Well, it had been a couple of weeks since they were charged completely up before I performed my test. I hope they are not shot they are only 3 years old.
I know the furnace fan always runs a lot faster when I am plugged into shore power then what it does from the batteries. But, I can go for 3 days without them getting run down if I am careful and don't use the furnace too much. The batteries are at the front of the TT and the furnace is near the back right next to the power converter. I always just figured the wire was too small and too long. I could use some new ends soldered on the ends of my cables but, I usually don't need to run the furnace when I'm dry camping anyway and it is the biggest draw. Everything else seems to run fine this way.