Voltage Drain

[Capflyer]

Lately I have been noticing a drain on my battery when all the switches are turned off including the master switch. Twice after a week of sitting idle my battery was completely dead. I have not done any changes to my electrical system wiring so I'm wondering if it is possible for the battery contactor to malfunction. I hear it click off when turning off the master. With the master off I measured about .45V on the bus which should have measured 0. Any thoughts on this or other possibilities out there in RV land?

 

[Lars]

Start by removing the cable from the switched side of the master and checking the buss voltage again. Do you have an always-on battery buss? Tell us some more about your electrical system architecture.

 

[Capflyer]

I do not have an always on buss connected to the battery. Everything flows from the battery through the contactor to the main buss. The only thing directly connected to the battery is my electronic ignition and that is turned on and off through my key switch which is always turned off after shutdown.

 

[Walt]

Might try disconnecting/checking to "spike" diode on the master relay, could be partially shorted/leaking.

 

[Capflyer]

Did a bunch of testing yesterday evening before running out of time. I disconnected the load side of the master contactor where the starter contactor and wire to the master bus are connected and there was no voltage across the contactor. So the contactor and diode on it are fine. There was however voltage when I checked ground to both the wire to the starter contactor and master bus while there were disconnected from the contactor. The essential bus only has two wires that go to my electronic ignition. Next I'll disconnect the essential bus and see if the drain is still there. I can't imagine where else the power is coming from. My backup battery is connected directly to the master bus but I pulled the breaker on it and it wasn't the culprit.

 

[FredMagare]

Essential Bus

Do you have a switch to the essential bus? If so, might that switch be wired incorrectly such that it appears to be in the off position when it is actually on? (Installed upside down? DPDT switch that is miswired?)

 

[Walt]

If you have it per the std Z11 than you have the essential bus running off the hot battery bus, start pulling those hot battery bus fuses and checking.