Originally Posted by
Jonestrollingmotor
About relays: First, I've had a starter/alternator shop for over 20yrs and been an ASC for Motorguide and MinnKota for close to 15yr. I say this so you will know I've encountered relays and solenoids many times during the past 20+ years. I've read with interest the views on using relays in place of a on/off switch. For several reasons a relay is not intended to replace a battery cutoff switch, but a relay, providing you get a continuous duty relay with the correct wiring / amperage draw, can be used in the application mentioned above. The relay from ebay mentioned above does not meet that criteria. It shows a max 30A rating which is fine for 1 talon (not two). It also shows "heavy duty" which is not "continuous duty". Contrary to what is said above, a relay/solenoid does draw current the entire time it's energized. Current moves through it two different ways. One way, it goes from positive ignition ignition, through a coil, to negative. This is present the entire time it's energized and allows for an electromagnetic field to hold a plunger contact across the negative and positive wiring contacts. The other way is through the wiring contacts. With these being a connection that is made by a copper contact going across the power in/power out contact internally, the connection gets hot and remaining engaged will cause the copper to "melt" and weld itself to the contacts internally. This causes the relay/solenoid to "hang in" or remain engaged when power is removed from the ignition side of the coil. A continuous duty relay/soleniod has nickle contact points to keep it from welding itself together. That being said, yes, a solenoid/relay will hang in if it doesn't receive proper voltage and is not the proper relay. Next problem with the one mentioned is the wire size. 18ga isn't meant to carry 30A. For a 30A rating it should be wired with at least a 14, preferably a 12 or 10ga.
Relays are used in our boats at the outboard motor, trim/tilt, hydraulic jackplates -- but these are not for continuous duty.
John