Newbie with electrical question..please help!

[Intruder345]

I just purchased my first Motorhome, a 1994 Damon Intruder 345B.
I have a few general questions, and i hope someone can help me.
1. Can someone explain the electrical system?
When sitting (not connected to 110 from the house) nothing inside works. I push the "Check Levels" switch i get nothing from the guages and i can't turn on the Generator, or lights. (I have just replaced the coach Battery's with new one's.) When i plug into 110 from the house everything works fine for a day or 2 then everything goes dead again, even while it's plugged in. I checked both batterys and the have 12 volts. Still can't turn on the Generator or lights. I have fliped every switch i can find ,and i'm stumped..If there is a link to help explain this that would be helpful.
Thanks in Advance
Jim

[RV Mech Tech]

Intruder345 - it sounds from your description that you have a wiring problem with the 12 volt side of coach electrical system - your RV has a high voltage (110 volts) system and a low voltage ( 12 volt ) system concerning the coach or 'house' side of the RV-( your chassis also has a 12 volt automotive system that is seperate from your coach with the exception of charging) - when you are not plugged in with the shore line you have 12 volts from the coach batteries that supply voltage to most of your interior lights (if not all) and other items such as your water pump, appliance control boards, ceiling fans, etc. but no high voltage - when you plug in your cord or run your generator ( either one or the other not both at the same time) you bring in high voltage into the coach that powers any house style outlets and any appliances that run on 110 volts such as the microwave, some appliances that have the option of both/either propane or electric such as the water heater or fridge and anything else that runs on HVoltage - also you have a converter that when you bring high voltage into the RV that power goes to the converter that then splits the 110 volts into the 110 system and converts some of that power to 12 volts and also it has a battery charger that keeps your coach ( and vehicle engine battery) charged up - you said that you have the same problem with both systems and there is no power for any of the 12 volt side- (generator starting system is 12 volts) - if both the new coach battery(s) are going dead and the converter system is failing as well I would suspect that you have a wiring problem on the 12 volt side and it doesn't matter where the power is coming from the power is not reaching anything or 'falling off' - I would check all the battery cables for corrosion anywhere that the cables are exposed and all electrical connections that are exposed on the 12 volt side- this goes for the positive and ground side- badly corroded connections will cause the symptoms you describe- the 12 volts coming from the converter will usually be a stronger signal and that explains why you have a short time that things work when plugged in - when you check your connections unplug your cord and put on your coach battery disconnect switch (check this switch also- it may defective!) so that nothing shorts out when you are checking- anytime EVERYTHING goes out at once indicates a power supply or grounding problem - the power my be o.k. but its having a difficult time reaching anything because of the bad conductors(s) -let us know what you find and sorry for the long post!