Forum Discussion

steverea's avatar
steverea
Explorer
Nov 15, 2015

electrical, is 13.4 volts normal?

I recently had the motor in my furnace replaced by an extremely experienced RV appliance guy. When I put the furnace back in it never ran right. The fan sounded weak. But it was putting out heat so I let it go a little while. then it quit working all together. so I checked the wires to make sure I had it hooked up right and it ran for a while and then quit again. Finally,I took it back to the guy and he said the new motor is toast. the brushes are melted and he suspects an electrical problem in the coach. I know very little about the system but I hooked up a meter to the wires that supply the furnace and I get a reading that fluctuates between around 13.2 and 13.6 volts. Is this a normal reading or is it high? The batteries are about 2 years old. I have two 12 volt batteries in series. the rv is always plugged in. The water level in both batteries is, and has been, good. thanks
  • Jim-Linda's avatar
    Jim-Linda
    Explorer II
    Nov 16, 2015
    omextreme wrote:
    A fully charged 12v battery will be 12.8 or 12.9+ Vdc. If you have 2 12v batteries in series then you would have 24v which would melt the brushes, I am assuming you have them in parallel. (+,+) (-,-) 13.4v is normal to the furnace with the inverter running charging the batteries. My control panel normally reads 13.4v in charge mode for my trailer.


    Inverter doesn't charge batteries, converters do.

    Jim
  • Rvpapa's avatar
    Rvpapa
    Explorer
    Nov 16, 2015
    You did have the furnace running when you measured the voltage ?
    Art
  • time2roll's avatar
    time2roll
    Nomad
    Nov 15, 2015
    All RV systems should operate fine from 10.0 volts to 15.0 volts.
    Converter output between 13.2 and 14.6 volts is common and normal.

    I might be more concerned about the fluctuation more than the actual voltage. Voltage should be very steady in general conditions.

    Seems odd for a new motor to fail like that.... if it was the right motor.

    I think you mean the two 12v batteries are in parallel.
  • enblethen's avatar
    enblethen
    Nomad
    Nov 15, 2015
    I believe what everyone is saying the voltage is not the problem.
    Replacement motor was defective or is could have had a drag on it like fan blades were hanging up.
    Make and model of your furnace?
    Any numbers on your old motor?
  • lanerd's avatar
    lanerd
    Explorer II
    Nov 15, 2015
    A fully charged 12v system sitting idle is 12.6v. However, you said your rv was plugged into shore power and the converter is running. Modern converters are three staged, which will keep the batteries fully charged by supplying approximately 13.4v. This is what you are seeing. If you disconnect the converter, your batteries will drop down to 12.6v (or so).

    HERE is a good explanation of how 12vdc in our rv's work. Good reading.

    Ron
  • omextreme's avatar
    omextreme
    Explorer
    Nov 15, 2015
    A fully charged 12v battery will be 12.8 or 12.9+ Vdc. If you have 2 12v batteries in series then you would have 24v which would melt the brushes, I am assuming you have them in parallel. (+,+) (-,-) 13.4v is normal to the furnace with the inverter running charging the batteries. My control panel normally reads 13.4v in charge mode for my trailer.

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