Alternator wiring

The PO had the alternator replaced, i saw old bills.


But it looks like he found a piss poor yard to fix it


you can see loose wires some out of the loom and a black wire that looks like it doesn't belong there


Also there's a part with several wires and some kinda copper wiring all exposed.


Can anyone shed some lite on the mess?

That looks like an electromagnetic relay that is missing the case.

Could be an old school voltage regulator.

When you figure out that mess it might be time to look at the thing behind the alternator. Looks like one bolt got dead shorted and half melted and the other is corroded. What is it?

Pete

I think those are zincs?


I'll look closer tomorrow

You need to trace the wires that go to the relay to see what it controls. It could be a relay that ties 2 battery banks together for charging when the engine is running.

Looks like a "cube" relay with cover missing. It might be connected to an oil pressure switch to prevent field energization until after engine is running. Can't tell from pic where red wire goes or what other wires are on relay.
Does the alternator work as is? if so replace the relay with new, return the wires to inside the loom where they belong, and put a new boot over the alt output terminal (heavy gauge wire in the back).

That is a heat exchanger back there with corrosion on what looks like zincs and/or drain plugs.

Cleaned up all the sloppy wiring, then compared to other engine,
not so bad all wiring appears the same ie: correct


Just this relay the one had a cover


what does it do,

It connects terminals 3 and 5 if there is power across terminals 1 and 2.

What are the terminals attached to? Where do those wires go?

Also, it looks like it is rated to 12V/25A, which is 300W. So, it is /unlikely/ for what should be a major like battery charging, etc.

If I recall they all go to the alternator.

Engine stop solenoid relay?

Lipets,

Without knowing where the wires go, we can only guess. Next time you are at the boat and have time follow as many of them as you can. With more info we can help more definitively (or you may find the answer at the end of one of the wires). But, that is basically a general purpose low wattage 12v relay, so could be used for many things. It isnt a specialized part.

Also, there is not normally a relay for the tach.

I'll be on the boat tomorrow and see where each go.


I saw something similar called it an electromagnetic starter relay????

That is the right type and spec for a starter relay on many boats -- but it could be many things. See where the wires lead.

If it is a starter relay what it does is allow long, cheap, low current wires running to the ignition switch to control the solenoid that operates the starter. The solenoid requires more juice than the relay and so would require thicker wires to the ignition switch(es) at the helm(s).

Wires connected to lugs 3 and 5 are being switched off and on, on when relay is energized, so some device is being disconnected and reconnected, a relay is an automatic switch.

I dont like the missing cover, and it already looks rusty. If its just a standard 40 amp cube relay, they use the same for automotive, will be easy to get and fairly cheap too. Bigger cube relays exist, I have two 70 amp rated. The rating may be printed on the cover. Bigger amp relays will have bigger lugs on 3 and 5, not 1 and 2 which are the coil wires that create the magnetic field that pulls the relay closed. For standard 40 amp rated relay, all lugs are same sizes.

Most likely its a NO relay just like automotive.

sdowney,

Oops. You are right. I got the switch and load pairs backward!

-Greg

Well I found a new replacement in the UK on Ebay $22


made in France!!!!!


Until it gets here I'll tape something over it so it doesn't short out.


But the mystery remains what it exactly does??

[But the mystery remains what it exactly does

Well, one option would be to disconnect it and see what doesn`t work..........or is that a bit non tech?






QUOTE=lipets;790360]Well I found a new replacement in the UK on Ebay $22


made in France!!!!!


Until it gets here I'll tape something over it so it doesn't short out.


But the mystery remains what it exactly does??[/QUOTE]

No need to wait for France. It is a common type of relay. You can bring it into any auto parts store and they can give you an equivalent one off of the shelf. What they sell you might look cosmetically different, but will work just the same, have at least as good electrical ratings, and the same size connections.

I suspect the wires going to the device it controls, e.g. the starter solenoid, will be in the engine room, on the same engine, and not far away. So, it really shouldn't be bad to look and see what it is for. Once you know that you'll be able to take a pretty good guess at the other end, e.g. ignition key switch.

When you choose to unplug the relay, make sure you take a clear photo of which wires go on which terminal because there is no standard socket installed. The wires will go everywhere when unplugged. It would be better to wait for the new relay and change one wire at a time.

lipets said:

Well I found a new replacement in the UK on Ebay $22


made in France!!!!!

Click to expand...

Don't bother.... 12V general purpose relays shouldn't cost that much, and you certainly don't need to have it sent across the ocean. Stop at your local Auto Zone, NAPA, or other retail outlet, or have Amazon drop one on your front porch. These are a good item to keep in inventory, there are myriad applications on board. I keep a couple since my Westerbeke uses them in the control circuits, they're a commodity item. Just get the correct configuration, or just keep a SPST or DPDT for wider application.



https://www.amazon.com/Dorman-88069...631&s=gateway&sourceid=Mozilla-search&sr=8-20

High Wire said:

It would be better to wait for the new relay and change one wire at a time.

Click to expand...

Already had that in mind, tks

Maerin said:

Don't bother.... 12V general purpose relays shouldn't cost that much, and you certainly don't need to have it sent across the ocean.

Click to expand...

I know, but it was the exact one and already mailed, I could have saved a bit

Not sure I would tape it, you might inadvertantly force the contacts closed all the time. The relay arm sits on topmost part and is easily depressed.

When reconnecting new relay, polarity wont matter. Just make sure relay coil wires are still relay coil wires and switch load wires are still that. They are very simple devices to understand electrically and a digital meter can show you that. they do usually have a schematic on them and if you look closely numbers maybe embossed into the plastic labeling the terminals. And the terminal orientation is designed so when plugged into a socket, they can only fit the right way.

Since they have no socket, likely a PO wiring job.

Relay terminal to terminal ohms be about 90 ohms.
Load terminal will be NO, Normally Open, no connection until relay coil energized, then they go to zero ohms.

I just helped a friend whonhad just installed a Balmar alternatorcon alternator on a Volvo diesel in his sailboat. A relay like that is required to get the charging light on the instrument panel to turn off when the alternatorcis charging. In his case the signal voltage with the new alternator is not high enough to activate the Volvo circuit.

There's a whole lot of things this relay could do. On a grand banks / ford lehman I had a relay that was used to turn on the alternators charging circuit (power the regulator) using the oil pressure switch so that the alternator would only work when the engine was running. Without that the field circuit would slowly drain the battery while the 'ignition' was on but the engine not spinning.

Antares said:

I just helped a friend whonhad just installed a Balmar alternatorcon alternator on a Volvo diesel in his sailboat. A relay like that is required to get the charging light on the instrument panel to turn off when the alternatorcis charging. In his case the signal voltage with the new alternator is not high enough to activate the Volvo circuit.

Click to expand...

I have the same on my Volvo circuit, attached to the big alternator. The other engine with a low output alternator doesn't have one.

"Without that the field circuit would slowly drain the battery while the 'ignition' was on but the engine not spinning."


Something was wired wrong.
Perhaps a single wire alt was replaced with a better unit with a 3 or 4 stage V regulator, or the key switch was replaced with the wrong one.