Forum Discussion

jdrocci's avatar
jdrocci
Explorer
Aug 22, 2020

Battery Disconnect Solenoid Fuse

2005 Holiday Rambler Ambassador 40PLQ

Under the driver seat on the outside is a compartment with a box that contains the battery disconnect solenoid. This solenoid has a nominal 5A fuse in the actuator circuit. Several times, I've lost all DC power to the house and found the cause to be this fuse. The last time it happened, I replaced the fuse with a 10A unit. Yesterday, with the MH parked in my driveway on shore power and the AC running, I locked up the unit and went inside my residence for the evening. This morning when I opened the MH for the day, I found all 12VDC circuits dead and the solenoid fuse blown again, This seems to have happened with no known stimulus.

Is this kind of failure well-known and if so, how/why does it happen?

Joe
  • jdrocci's avatar
    jdrocci
    Explorer
    Aug 22, 2020
    I'll do a test tomorrow. I think pulling the fuse should have no affect if it's a latching solenoid. If pulling the fuse disables the 12V, then it's electrically held
  • Dusty_R's avatar
    Dusty_R
    Explorer
    Aug 22, 2020
    But with a latching relay, when latched, even if the control circuit dies, the things controlled by the relay will continue to work.

    Unless they are on the same circuit.
  • jdrocci's avatar
    jdrocci
    Explorer
    Aug 22, 2020
    Thanks for all the insights guys. What's perplexing to me is that the fuse apparently blew during the night when there was no activity in the MH.
    I guess it could have happened when I closed up...maybe I accidentally hit the salesman switch on the way out, which MAYBE caused a momentary short. I doubt that though.

    It's a weird one. If I get to the bottom of it, I'll update this posting
  • dougrainer's avatar
    dougrainer
    Nomad
    Aug 22, 2020
    The solenoid is called a "Latching" solenoid. It is called this because once closed or open, it draws NO POWER. So, the 12 volt 5 amp fuse should only blow when the Solenoid is activated or deactivated. If this is the case, the solenoid is probably bad and has a short in the Latching circuit. Another possible cause would be the wiring from the Disconnect switch has a short feeding the solenoid. Can you determine by trial and error if the fuse will blow if you try to Open and close a few times in a row? DO NOT INSTALL A LARGER THAN 5 AMP FUSE. There is a REASON it is on a 5 amp circuit. Is this fuse on the large Circuit Board, or is the fuse attached to the actual Solenoid. Monaco used both types. Doug
  • enblethen's avatar
    enblethen
    Nomad
    Aug 22, 2020
    The battery disconnect solenoid should be the only draw on the five amp fuse.
    Power from fuse should go to switch and then return to the coil of the solenoid. I would check the wiring around the switch and solenoid for loose connection and damaged insulation.
    Switch is normally a double pole double throw momentary switch.
    Solenoid should draw somewhere around one amp so five amp fuse should be plenty.
    Verify that previous owner has not connected other load.
    Locate which solenoid your rig is equipped. There is some rigs that have an electrically held solenoid and not a latching type.
    I am using solenoid , but I like to call they a relay!
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Aug 22, 2020
    Not common. If you're referring to the salesman switch then they use a latching solenoid (mechanically latched) and draw no power except when you push the button.
  • ksg5000's avatar
    ksg5000
    Explorer
    Aug 22, 2020
    Might consider replaying the relay - there not that expensive. In my rig there are two solenoid/relays. One is a latching battery disconnect intellitec relay which has two fuses ... the other is std solenoid used to combine/disconnect chassis/coach batteries based on the position of the ignition key.

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