House Disconnect Latching Relay Failure

[Fil]

Twice I have replaced the KIB LR9806 Latching Relay on our Axis 25.1 (house disconnect under the fridge). We are the second owners and I suspect the PO replaced it as well. My relay has a small auxiliary circuit board whose purpose is unknown to me (activate the relay when genny starts or shore power comes on?) (see picture). This time when I replaced the relay I disassembled the old one to confirm that the coil had failed (burned out) which I suspected since the fuse on the relay had blown. My question: Why did the replay coil burn out? I suspect that something was keeping the coil activated long enough to cause a failure. Note: I've had problems with the chassis battery and have made extensive use of the emergency start option. I'd love diagnose this once and for all.

[Ghostvette]

Originally Posted by Fil

Twice I have replaced the KIB LR9806 Latching Relay on our Axis 25.1 (house disconnect under the fridge). We are the second owners and I suspect the PO replaced it as well. My relay has a small auxiliary circuit board whose purpose is unknown to me (activate the relay when genny starts or shore power comes on?) (see picture). This time when I replaced the relay I disassembled the old one to confirm that the coil had failed (burned out) which I suspected since the fuse on the relay had blown. My question: Why did the replay coil burn out? I suspect that something was keeping the coil activated long enough to cause a failure. Note: I've had problems with the chassis battery and have made extensive use of the emergency start option. I'd love diagnose this once and for all.

Just a guess, but it looks like the relay can't handle the current. It appears to be a 15A AC (alternating current) relay and the air conditioner alone pulls 20A, so I'd get a relay that will handle 25A and you might solve your problem.

[Fil]

Thanks. I'm sure that's not the problem. This is the OEM relay from Thor. It's got a spring-loaded buss that looks easily capable of handling 50 amps. Wish there was a data sheet I could point at but it's Chinese. The problem is the relay actuator coil failed. It won't draw more than 5 amps (the coil circuit is protected) but it looks like the coil is being activated continuously under some circumstances that I have been unable to diagnose.

[Ghostvette]

Originally Posted by Fil

Thanks. I'm sure that's not the problem. This is the OEM relay from Thor. It's got a spring-loaded buss that looks easily capable of handling 50 amps. Wish there was a data sheet I could point at but it's Chinese. The problem is the relay actuator coil failed. It won't draw more than 5 amps (the coil circuit is protected) but it looks like the coil is being activated continuously under some circumstances that I have been unable to diagnose.

Do you have an 'amp clamp'? It's something that goes around a wire and will measure current flow. That would give you an idea of where the current might be coming from.

[Fil]

I do - but the problem is intermittent - so nothing to trace. But you did give me a couple of ideas. (1) I might put in slow blow fuse on the circuit. (2) I just discovered an unfused leg of the coil circuit and (3) my leading contender - as I said I was dealing with battery issues when this last happened - it's possible the coil burned out under a low voltage situation which increased the amps through the coil burning it out.

[16ACE27]

The battery disconnect latching relay has nothing to do with and no connection to/from:
The generator
The emergency start switch

If the activating coil is consistently burning out it's because it's constantly powered. This could be a wiring or activating switch issue. If the activating switch is "sticking" intermittently that could cause the problem you are seeing.

Verify the current wiring and if good, replace the switch.

[Fil]

Not sure if this thread is active. I've just replaced the latching relay in my 2017 Axis for a second time due to the coil burning out. This can only happen if the coil is continuously energized - still haven't figured how that can happen. The KIB LR 9806 latching relay works exactly like a ball point pen clicker. When a current is applied a plunger moves down (polarity doesn't matter - another myth). If the relay was not engaged, it latches, and the battery is connected to the power center. If the relay was engaged it disengages and the battery is no-longer connected to the power center. This is why the use/store toggles the house systems when on battery power regardless of what direction the switch is pressed. What else is going is a mystery to me. The Use/Store switch has 6 wires coming into it. Two come from the relay. Another is fused power and another is ground, the other two are a mystery. They relay also has a secondary relay that is a mystery to me. The secondary relay receives a signal from somewhere and is wired in parallel to the latch relay so that the mystery signal can activate the latch. I wish there as a complete wiring diagram for the Axis but I've only been able to find some partial schematics. Would love to get a complete wiring diagram.

[16ACE27]

Originally Posted by Fil

Not sure if this thread is active. I've just replaced the latching relay in my 2017 Axis for a second time due to the coil burning out. This can only happen if the coil is continuously energized - still haven't figured how that can happen. The KIB LR 9806 latching relay works exactly like a ball point pen clicker. When a current is applied a plunger moves down (polarity doesn't matter - another myth). If the relay was not engaged, it latches, and the battery is connected to the power center. If the relay was engaged it disengages and the battery is no-longer connected to the power center. This is why the use/store toggles the house systems when on battery power regardless of what direction the switch is pressed. What else is going is a mystery to me. The Use/Store switch has 6 wires coming into it. Two come from the relay. Another is fused power and another is ground, the other two are a mystery. They relay also has a secondary relay that is a mystery to me. The secondary relay receives a signal from somewhere and is wired in parallel to the latch relay so that the mystery signal can activate the latch. I wish there as a complete wiring diagram for the Axis but I've only been able to find some partial schematics. Would love to get a complete wiring diagram.

Have you created an account at the Thor Owners Resource website with your VIN? You can access available electrical diagrams there. None are true schematics or true wiring diagrams.

[PreCambrian]

I found a relay datasheet here. https://pdf1.alldatasheet.com/datash...1-35-1012.html

The datasheet doesn't mention any duty cycle so I would assume that it is rated for 100% operation. I am unfamiliar with this type of house disconnect, I just have a rotary switch. However this relay probably energizes a solenoid that connects or disconnects the batteries from the DC distribution panel/converter. It looks like a solenoid in the back of the photo. It also sounds as if there is some sort of latching circuit wired to the coil, at least according to some of the descriptions.

The coil could be burning out due to low voltage (probably less than 9VDC) or because the area is getting too hot. Check the connections at the solenoid and other wiring in the area. I use a Seek Thermal Infrared Camera for iPhones for this. https://www.thermal.com/compact-series.html

The infrared cameras are good for all sorts of thermal issues including leaks and seals.

[Chateau_Nomad]

Question: Why a latching relay for a battery disconnect... vs a directly wired manual disconnect switch - like a Blue Seas?

Mine is simply a manual switch wired into the positive battery cable.

Advantages? Disadvantages? I'd like to learn something new today!!

[OldWEB]

Originally Posted by Chateau_Nomad

Question: Why a latching relay for a battery disconnect... vs a directly wired manual disconnect switch - like a Blue Seas?

Mine is simply a manual switch wired into the positive battery cable.

Advantages? Disadvantages? I'd like to learn something new today!!

Convenience? Why not pull chains or screw in the light bulb instead of a remotely operated wall switch?

[OldWEB]

I found this...
KIB relay


Then this description says differently...
LR9806J-BIP

[DavidEM]

Newish Axis, mine is a 2021, have a simple rotary switch to disconnect the converter panel from the battery. I am very glad I have this and not a latching relay which is much more complex and prone to failure.

The only reason I can see for using a latching relay is geographics- the battery is in a remote place where a rotary switch would be difficult to access.

David

[OldWEB]

Originally Posted by DavidEM

Newish Axis, mine is a 2021, have a simple rotary switch to disconnect the converter panel from the battery. I am very glad I have this and not a latching relay which is much more complex and prone to failure.

The only reason I can see for using a latching relay is geographics- the battery is in a remote place where a rotary switch would be difficult to access.

David

You real?
Your "Newish Axis" from what I see in the brochure has...

• Power Patio Awning with Integrated LED Lighting
• Electric Stabilizing System (maybe)
• Heated/Remote Exterior Mirrors with
  Integrated Side View Cameras
• Emergency Engine Start Switch (very similar to the subject disconnect switch)
• Power Drop-Down Hide-Away Overhead Bunk
• Winegard ® ConnecT™ 2.0 WiFi / 4G / TV Antenna
• Automatic Generator Start (AGS)

And what I think is the craziest system ever for a RV...

• Rapid Camp+® Multiplex Wiring Control System

Then you are 'very glad' with a manual switch.

[Chateau_Nomad]

Originally Posted by DavidEM

Newish Axis, mine is a 2021, have a simple rotary switch to disconnect the converter panel from the battery. I am very glad I have this and not a latching relay which is much more complex and prone to failure.

The only reason I can see for using a latching relay is geographics- the battery is in a remote place where a rotary switch would be difficult to access.

David

That's what I thought... especially the "geographics". I know how the relay works (elevator button light). I guess there's motorhome scenarios where perceived convenience outweighs the complexity/failure rate?? Or the house battery bank is in a rear storage compartment - far removed from easy access??

I honestly was NOT trying to be a smart a** or disagreeing/ridiculing the use/need for a latching relay... but just trying to understand a logical use case.

[16ACE27]

Originally Posted by OldWEB

You real?
Your "Newish Axis" from what I see in the brochure has...

• Power Patio Awning with Integrated LED Lighting
• Electric Stabilizing System (maybe)
• Heated/Remote Exterior Mirrors with
  Integrated Side View Cameras
  
• Emergency Engine Start Switch (very similar to the subject disconnect switch)
• Power Drop-Down Hide-Away Overhead Bunk
• Winegard ® ConnecT™ 2.0 WiFi / 4G / TV Antenna
• Automatic Generator Start (AGS)

And what I think is the craziest system ever for a RV...

• Rapid Camp+® Multiplex Wiring Control System

Then you are 'very glad' with a manual switch.

No, completely different. The EMERGENCY START switch applies power to a solenoid that requires power to stay activated.

The USE/STORE switch (battery disconnect) is a momentary switch that only apples power to switch the state of a latching relay. No power is required to keep it in that retained state.

[16ACE27]

Originally Posted by PreCambrian

I found a relay datasheet here. https://pdf1.alldatasheet.com/datash...1-35-1012.html

The datasheet doesn't mention any duty cycle so I would assume that it is rated for 100% operation. I am unfamiliar with this type of house disconnect, I just have a rotary switch. However this relay probably energizes a solenoid that connects or disconnects the batteries from the DC distribution panel/converter. It looks like a solenoid in the back of the photo. It also sounds as if there is some sort of latching circuit wired to the coil, at least according to some of the descriptions.

The coil could be burning out due to low voltage (probably less than 9VDC) or because the area is getting too hot. Check the connections at the solenoid and other wiring in the area. I use a Seek Thermal Infrared Camera for iPhones for this. https://www.thermal.com/compact-series.html

The infrared cameras are good for all sorts of thermal issues including leaks and seals.

That relay is nowhere near the type of relay that is the discussion of this thread.

[DavidEM]

OldWEB:

I totally agree that there are a lot of complex and in some ways silly electronic systems on my 2021 Axis. But the simple rotary battery disconnect switch isn’t one of them.

David

[OldWEB]

Originally Posted by 16ACE27

No, completely different. The EMERGENCY START switch applies power to a solenoid that requires power to stay activated.

The USE/STORE switch (battery disconnect) is a momentary switch that only apples power to switch the state of a latching relay. No power is required to keep it in that retained state.

I am intimate with the relays used, just indicating that it is remotely operated also, like the battery disconnect.

Wondering why they would have it when a set of simple booster cables could be manually used.

[Fil]

Thanks. Yep. Got the wiring harness diagrams. At least it tells you where to look for the wires. :-)