Seloc sez marine solenoids ONLY ... ???

my seloc manual says that you CANNOT use solenoids off of a car cause they will ground out ... you have to use marine solenoids ONLY<br /><br />now ... why is this? arent the solenoids just like mechanical transistors, using small voltage to control large amperage?<br /><br />I have the 56 - 72 Seloc covering up to 40 horse motors, its a great manual, seems like its more detailed than the Clymer which I ALSO have, but it does have some very confusing things in it<br /><br />

Re: Seloc sez marine solenoids ONLY ... ???

To answer your question, they are not like transistors at all. Current can actually go both directions on a soleniod. Soleniods act just like a switch. Voltage induced at 12vdc through coil causing starter to spin. Marine soleniods have more windings inside than an automotive soleniod due to the amount of current that is needed to start your motor. (just for your info, my 73-91 seloc says the same)

Re: Seloc sez marine solenoids ONLY ... ???

Solenoids for both automotive and marine applications work on the same basic principal. Both use a small voltage applied to a coil to magnetically close a set of larger current carrying contacts. The gauge and number of windings of the coil inside the solenoid determines the amount of battery current needed to close the high current carrying contacts. The coil circuit and the high current contact circuit are independent of each other. Current through the coil has nothing to do with the amount of current needed to spin the starter. The coil current and the starter current must be added together to get the total current draw of the starting system. I can not see any reason why an automotive solenoid can't be used in a marine application. A large transistor could be used to accomplish the same thing but would not be cost effective. The large current draw of the starter would neccesitate a large heat sink. Additional parts would be needed to minimize back EMF when the starter stops. So, the KISS principal really applies here.

Re: Seloc sez marine solenoids ONLY ... ???

Marine solenoids meet the Coast Guard spark suppression regulations, so they will not ignite any gas fumes in your bilge.<br /><br />On outboards, marine solenoids use the 2 small temminals for the ground and for the key switch. On a car, the solenoid is grounded thru it's mounting plate and the second small terminal is fot the ignition by-pass.

Re: Seloc sez marine solenoids ONLY ... ???

Seahorse, Thanks for the additional info. Meeting Coast Guard regs. for explosion proof parts is a major consideration. I only considered the electro-mechanical aspects of the solenoid.

Re: Seloc sez marine solenoids ONLY ... ???

hello Ray.<br />If you are going to use the starter/solenoid boxes which are on the '59s (you know those little white boxes away from the engine)your solenoids will have to be a specific size.<br />Anyway the marine solenoids are only about 25 dollars a piece.