Coach power

[Tom Csibor]

2000 Beaver Marquis.
Coach power not working. All 6, 6v batteries are good and 12v going to the coach when the coach master switch is OFF. As soon as the switch is turned to ON the output voltage drops to 4v and nothing 12v based is getting power

[David T. Richelderfer]

1.  Plugged into shore power?  No, or Yes with 30 amp, or 50 amp?
2.  Aqua Hot diesel burner and thermostats are ON to provide interior heat?
3.  Fridge is ON?
4.  Insta-Hot at kitchen sink is ON?
5.  Ceiling lights are ON?  Halogen or LED?

It sounds like something electrical is turned on and the house batteries are not fully charged.  If the house batteries are fully charged, then without the inverter-charger engaged, they should be showing 12.6 volts.

[Fred Brooks]

   Tom,
How old are the 6-6volt batteries? Are the terminals clean and no evidence of corrosion? Is the switch on the dash that says "coach power" turned on?. Is the coach plugged into a 50amp service and inverter panel above the passenger seat show that the house batteries are charging?. If the batteries are junk, they may show a "surface charge" of 12.6 but when a load is applied, the voltage really declines. Give me a call @520-309-1260 for more trouble shooting. Fred

[Tom Csibor]

Thank you for the replies. Tracked it down to a shorted 6volt battery.