My engine battery keeps dying overnight even though I have nothing on. I have the house battery which will say its good and charged but still dont use anything electrical and by morning everything is dead. I even bought a brand new battery and same thing keeps happening. I have an invertor box in the rv (Im VERY new to RV's and how all of this works) and I dont think its working. How do I tell if its working? Does anyone have any idea why the battery is dying constantly? Please help. Im on the road alone and dont know much about how to fix this problem so any advice would be greatly appreciated.