What is this round black thing?
I have gotten tired of going out of the TT, opening the battery box, and turning ON the Blue Sea Disconnect Switch whenever we are boondocking and want to watch a video, then going back to turn the sw...
Forum Discussion
MrWizard wrote:
Strange
I don't know why there would be a capacitor or a diode, across the switch on off terminals
And the lead is too small for the load contacts terminals, which is where it would be most useful to prevent arcing
From the size of the lugs I'm guessing it is a diode. The "Tab" goes to a mounting bolt and the Wire terminal goes to the control stud on the Big Boy.. Placing a diode (reverse biased) across a coil is a very common practice..
WHY.. Ok, first you need to know I went to college and studied exactly this stuff.. So I tend to go into too much detail.
When the RELAY engages. NO tribble. But when the switch is opened and it Drops out there is this big electro magnet (COIL) and as the magnetic field collaspes it tries to keep the current flowing. So the bolt that was POSITIVE when the on/off switch was ON. now is Negative. and it can easily be 100 volt or more Negative for a brief period. This causes the remote switch to arc and burn up.
BUt the diode clamps the negative voltage to like 2 or 0.2 depending on the diode. No arcing, No damage to the switch because when that terminal on the coil goes NEGATIVE.. the diode is now Forward Biased. and current flows freely till the magnetic field is toast.
Diodes are like check valve on a water system.. In this case it is more like a vacuum breaker.
