I have a 2001 Lance 845 that is new to me. I've had problems with the battery going down and don't know why (I bought a new battery but I'm using the old camper battery for another application). Someone checked out the fuse panel with a multimeter and told me the freshwater pump was drawing down the battery. The other circuits were ok. My travel trailer pump would cycle every few minutes so it was always turned off when not in use but in the Lance the pump never cycles so it's easy to forget to turn it off when not in use.
I'd like to learn more about the electrical system. I think I know how the refrigerator works on 12v and 110. The AC is pretty straight forward.
I see the lights brighten up when I plug in so there must be some interface between 110 and 12v. Does this also power the pump when plugged into 110? Is there a battery charger in the camper and is it automatically charging the battery when necessary? Is there an electrical schematic available on line?
I assume the camper will not drain my truck battery and my truck will not charge my camper battery.
The last two weekend trips were fine with little use of the 12v but I'd like to be able to do some self-contained camping and know I'll have lights for a night or two.
Thanks
Doug

Thank you all for your replies. Very informative. I just put it up in the barn until we go south in Jan or Feb. I disconnected the battery and I'll have to check it out then.
Doug

I see mention of using a solenoid in the charge circuit but relays can stay locked on, draining
vehicle battery use an isolator.properly wired
for your vehicle as isolator are proportionate
to charge .Using a relay , when the vehicles main battery voltage is at regulator cutoff the alternator output will drop and because off the added resistance due to wiring length the camper battery will not see proper charging.with an isolator once the vehicle battery voltage is at cutoff the isolator will still charge the camper battery.You must increase the wires diameter to TC's battery
to allow adequate flow perfered # 4 gauge at least.My 550 has a three way isolator 1 branch
controls vehicle batteries 2nd branch controls
the group 27 on the side of TC and 3rd branch
controls charge of 2 interstate 6 volt deepcycle
batteries paralled to 12 volts.Over the last 8 years we not experienced any problems .We mainly
boondock and have had no need for a gen.The most
irritating thing is to be out in God's country
peacefully fly fishing and hear some jerk running his gen so he can use his microwave or
use every light or run his furnace all night and need to charge his batteries everyday .We
can dry camp for one week on the group 27 and
2 weeks on the 6 volts.Only four times have we
every camped since 1971 have I ever used shore
power. If you are careful you can do it to.
Don't cheap out on your batteries buy top of the line and have your wiring correct.

You can also go to the site, 12 volt side of life. More info than most folks know what to do with. Very good site.

You didn't mention how long it takes the battery to go down. The water pump will not drain the battery if it doesn't cycle on and off. I suspect there are other 12-volt devices draining your battery i.e. the propane leak detector, CO detector (if you have one) and the factory radio/cd player clock and memory and if radio is left in the sleep mode and not turned off completely.

The truck won't charge the camper battery unless camper's battery charge wire in the camper wire harness is connected to the truck's battery. If you have the (optional in 2001) built in battery separator, the camper battery will not discharge the truck battery. Some dealers install a relay in the camper battery charge line to prevent discharging the truck battery.

The lights in your camper brighten when the electrical cord is plugged in to 120-volts AC because the converter that changes 120-volts AC to 12-volts DC automatically comes on. It furnishes power to the 12-volt devices and charges the battery when ever the cord is plugged in. If you leave the camper plugged in to 120-volts for a long time, check the battery electrolyte level at least every two weeks. The Magnetek converter used in the 2001 Lance campers will overcharge the battery and "boil out" the water.

Using battery power for a couple of nights depends on how much you use the 12-volt devices i.e. water pump, forced air heater, lights, etc., how well the battery is charged, and the battery capacity. Do not try to operate the fridge on DC when parked. It will drain the battery quickly.

There should be a drawing of the 12-volt wiring schematic in your Owner's Manual furnished by Lance.

Bill