when i park my Barth for a weekend or longer, plugged in or not, the batteries go dead unless i use the disconnect. the batteries are all new. what would i look for?
93 breakaway,cummins, allison.

Do you have a multimeter?

If so, use the DC ammeter to read current. Then, one at a time, remove fuses until the meter goes to zero. Sometimes it is a closet or outside light that goes undetected during the day. Or a propane detector.

Is your water pump fused? Sometimes they will just have an inline fuse. If there is a small water leak or a leakdown in the pressure side, the pump will come on for a moment every so often, often undetected.

If removing the little fuses does not do it completely, remove the large main fuse. If that does not do it, you have a load that is not fused, or at least does not use the normal fuse set up.

I am speaking generally here, as your BK could be different from my gasser.

Be careful with a hobbyist-grade ammeter. They can usually tolerate no more than one amp.

However, the voltmeter can serve the purpose for larger drains - if there's someting on, there will be voltage shown.

Another way to test is to disconnect the positive connection to batteries between coach (house) and or engine. You then can check for load/resistance between the positive cable and the negative cable. Using V=IR where V=volts (12) and I=amps and R=resistance you can figure how big a 12V load you might be looking for. If you have fuses or breakers you can trip them one at a time to see if the load goes away. If it doesn't pull the main fuse/breaker just to be sure it isn't a fused load. If you still have a load showing you may have an exposed wire or a circuit that is either not fused or has a fusible link.
Find out the resistance and let us know so we can confuse you with further speculation.
Good luck
Tim

All Barths are not alike, but ours has two drains that do not go through the main fuse. These could drain power even if the main fuse were disconnected.

1. The indicator light panel above the door. You know, the one that has the digital clock and push buttons to indicate tank levels, etc.

2. The stairwell step light that comes on when the door is open.