Low Voltage Problem

[kellyw]

I have a 1974 Soverign 31' airstream. How do I go about troubleshooting a 12V low voltage problem? With the trailer connected to commercial power, a fully charged battery will completely discharge over night. The 110V circuits still work okay. I do not own a maintenance manual for this trailer. Any suggestions are greatly appreciated.

[john hd]

do you hear any humming from the univolt unit when you plug the trailer in?

john

[FrankR]

To determine if a battery is being discharged, first the battery must be checked to determine battery condition. A battery is fully charged when the voltage is measured with a digital volt meter and the voltage is 12.6 or 12.7 volts. If a battery is 12.0 volts the battery is 75% discharged.
An easy way to determine what 12volt circuit is using power is to remove all fuses from their holders. Before removing fuses, note their position as to amps. Indivually replace one fuse at a time and note any sparking as fuse is installed. Nope the 12 volts will not shock or harm any human. If no sparks are noticed. check battery and disconnect the ground cable untill some 12-15 hours have passed. Then again check battery voltage. If possible make all the checks with the 120 volt ac not connected. NO shore power. Depending on results of tests, more checking maybe required.

[kellyw]

To john hd: I did not notice any humming from the univolt unit when you plug the trailer in.

To FrankR: Thanks for your help. I suspect my problem may be in circuit#4. How can I find out what area of the trailer is serviced by circuit#4? The reason I suspect this circuit is because the ohms reading across the positive and negative battery connectors (with the battery disconnected) is close to a short until I pull out the fuse for circuit#4. I will try what you suggested, however it will be awhile before I get back down to the trailer to check it out.

Thanks for the help,
kellyw