I acquired an Intellitec battery disconnect relay to add to my RV to remotely disconnect the coach battery. After going through all of the project hassle to install it along with the remote switch wiring, I found that it was somewhat broken. It would activate and deactivate as it should, but over a little bit of time, it would reconnect the circuit on its own and without any power from the switch. Not knowing how these things worked, I decided to jump in and see what I could learn.

Taking this unit apart was a simple four screw operation and the entire thing splits open. One side is the coil and the other side is the latching mechanism. After a little inspection and probing it became clear to me how this works and why it had been failing.

The simple explanation of the latching mechanism is that it is an addon to a normal coil operated relay, where a magnetic pendulum is either attracted to the center of the main contact plunger or it is repelled from the center of the plunger where at the point of release of the coil voltage, the main plunger is either held in place by the pendulum or allowed to return to rest as an open circuit assisted by the plunger return spring.

In my unit, the plunger return spring had weakened allowing the plunger disc to eventually remake contact on its own. I suspect this is an age, wear and storage heat issue. So what I did to "fix" it was to take the return spring in hand and carefully stretch it beyond its elastic point making it longer. This makes it apply more force when compressed so it should do the job better.

You can see this photo gallery here:


Here is a video I made up:

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[kb]5, Battery Disconnect Relay Repair[/kb]

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