What EXACTLY Is this?

[hellosailor]

" If all it did was choose between 2 batteries then a simple 1/2 selector switch could do that without electrical stuff to complicate things "
Not really. Consider that you want maximum power to the starter. That means ideally you would want the cable from the battery(s) to the starter relay being as short as possible. If you do that with an A/B switch, the switch might need to be located 4? 8? 10? feet away from the actually battery cables, creating (both directions add) possibly a 12-20' extra power drop in the cable.
By using a relay, you can put the A/B switch where it is convenient to the electrical panel, and still keep the actual power cables really short (and cheaper and more efficient).

Sure, it violates KISS. And that unit looks like it has been rather neglected and possibly corroded. But the idea is solid, and a common way to avoid line power losses.

[gettinthere]

HS
Thanks for that. The way I'll be set up I don't think I'll be changing the distance very much at all. Maybe 3 or 5 percent

[delmarrey]

Where does the other end of the cables go? Starter, windlass or ??????

[Cr8tiveSailor]

Originally Posted by delmarrey

Where does the other end of the cables go? Starter, windlass or ??????

You'll have to provide that info.

[unbusted67]

What exactly doe a solenoid do? All I know about them is that, in my old car, I used to have to hit mine with a hammer before it would start.

[delmarrey]

Originally Posted by unbusted67

What exactly doe a solenoid do? All I know about them is that, in my old car, I used to have to hit mine with a hammer before it would start.

It's a magnetic switch in which you can use a small amount of amps to operate the magnet to pull together a large set of contacts for a high amp connection. Commonly used for starting electrical motors, in turn can start larger motors.

[Blue Stocking]

GordMay's signature line says it all

[doug86]

Originally Posted by gettinthere

So why is this solenoid preferred over a 1/2/both rotary switch?

Because you can activate the solenloid switch remotely from the helm position, rather than having leave the wheel and go to where the 1/2/Both switch is. Particularly handy for a flybridge application.

[delmarrey]

Originally Posted by Christian Van H

Wacking............... Wish it worked for people...

Nothing works on some people!

[Stillraining]

WAIT!...What ever yo do don't remove that thing....Gosh! Darn!...I cant believe Im the only one who caught this...That thing is all that's keeping your boat from burning to the watter line.

Its called the cusziffit...cuz-if-it wasnt there all them wires wouldn't have a place to go..and you don't want them going touchy-feelie just anywhere..now do ya!

Now what you do is is carefully round up the females...they be the hot ones..at least usually the striped ones so watch carefully the exposed ends...next keep them males from touching them or the sparks will fly and you may get babies....baby fires.. Now once you have them separated put some cloths on the ends so their not attracted to one another then get you oars out cause you ain't going to be able to make fire in the hole now or be motoring anywhere...but at least you defused the situation.

On the other hand...Might be best to just clean up them little naked ends and cover tings up with some rubber slip covers...keeping the attraction under control with lock and key

All right ...you guys get your mind out of the gutter..This is serious electrical talk...

[AnchorageGuy]

Originally Posted by doug86

It sounds like this is a parallel solenoid that allows you temporarily connect your house bank to the starting circuit. It was intended as a quick alternative to a large 1/2/Both battery selector switch, so that in an emergency, you could just throw the switch you mentioned (that makes the solenoid click), rather than have to climb down to your battery switch.

This pretty much what it is. WG

[gettinthere]

thanks everyone

I'll be replacing this with a cole hersee rotary switch along with other re-wiring. And yes I'll be doing a much better job of crimping wires and sealing with adhesive heat shrink.

This is what I thought it is but I wanted to be sure, just in case.

I read somewhere that the only stupid question was the one not asked