Battery Disconnect Switch stuck to "On"

[Ghh]

Thanks. I’m going to need it. I’m clearly out of my element. I’ll let you know how I made out.

[OldWEB]

Grasping here, but you may also try to un-mount the relay and put it in a more vertical position. I could not find info on how it should be orientated, maybe it really does not matter, but something 'easy' to try.

[Ghh]

Good idea. It’s in a horizontal position now. Thanks.

[JeeperCamp]

Sorry to jump in but I’m having a similar issue except I just bought this RV and it appears previous owner had the issue and tried rewiring it based off the not stock wire eyes and had placed what looks like an old rusty ford starter relay. I purchased a BD relay solenoid and replaced it now 12v is stuck on, I press the momentary switch, and hear the solenoid click but no disconnect. Seems like there is only power going to one side of the solenoid while button is depressed and the other is going straight to ground.

[javelin]

Originally Posted by JeeperCamp

Sorry to jump in but I’m having a similar issue except I just bought this RV and it appears previous owner had the issue and tried rewiring it based off the not stock wire eyes and had placed what looks like an old rusty ford starter relay. I purchased a BD relay solenoid and replaced it now 12v is stuck on, I press the momentary switch, and hear the solenoid click but no disconnect. Seems like there is only power going to one side of the solenoid while button is depressed and the other is going straight to ground.

Welcome to the forum. I don’t know what battery management system a 99 Fourwinds coach uses, but I am attaching an Intellitec schematic as an “example” of a typical battery management system (may not be what you have). The isolator relay in the middle is a typical “old Ford style starter relay” which operates when the control pins receive +12vdc and ground. It stays operated as long as control voltage is maintained......it is not a latching relay. The two relays on either side of the isolator relay are latching relays, which will stay either latched “on” or “off” depending on the polarity of the voltage applied on the control pins of each relay. They stay in that on/off position when the control voltage is removed.


So it is possible that the previous owner of your coach tried to replace a failed latching relay with a regular (non-latching) relay. It is also possible that something is just not wired correctly. You need to determine what battery management system you have and how it is supposed to be wired. Pictures may help the forum help you; or someone else with your coach/year may jump in with the required info.

[JeeperCamp]

Originally Posted by javelin

Welcome to the forum. I don’t know what battery management system a 99 Fourwinds coach uses, but I am attaching an Intellitec schematic as an “example” of a typical battery management system (may not be what you have). The isolator relay in the middle is a typical “old Ford style starter relay” which operates when the control pins receive +12vdc and ground. It stays operated as long as control voltage is maintained......it is not a latching relay. The two relays on either side of the isolator relay are latching relays, which will stay either latched “on” or “off” depending on the polarity of the voltage applied on the control pins of each relay. They stay in that on/off position when the control voltage is removed.

So it is possible that the previous owner of your coach tried to replace a failed latching relay with a regular (non-latching) relay. It is also possible that something is just not wired correctly. You need to determine what battery management system you have and how it is supposed to be wired. Pictures may help the forum help you; or someone else with your coach/year may jump in with the required info.

Ok thank you, that sort of clears some things up I’m just fuzzy on what or how the momentary switch works to switch the polarity to the latching relay or if another piece of my puzzle is missing.

[javelin]

Two position (center off) momentary switches are normally used with latching relays in RVs. In the up position they provide a certain polarity (+,-) voltage to the control pins of the latch relay; in the down position they provide the opposite polarity (-,+) voltage to control pins of the same latch relay. This enables the latch to operate or release and stay that way when the momentary switch is released to center off (no voltage applied) position. Read OldWEB’s post #19 in this thread to learn how the typical latch relay works in more detail.


By the way, I referred to “old Ford style starter relay” in my previous entry only to give you a comparative relay function (that you are probably aware of) for the isolator relay in the Intellitec schematic. You should note though that an old Ford style starter relay is not meant for continuous duty (always on; or on for long periods). There are special relays built to be able to stay operated and used as an isolator relay for RV battery control circuits.



The isolator relay can be used to momentarily connect the coach and chassis battery together to allow you to start your RV engine (if chassis battery is discharged); or the isolator relay can be operated for much longer times, to allow the alternator to also charge the coach batteries when the engine is running and the coach batteries require charging. The BIRD electronics and the aux start switch in my previous diagram determine when the isolator relay operates. Hope that helps.